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1/*
2 * CFQ, or complete fairness queueing, disk scheduler.
3 *
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
6 *
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
8 */
9#include <linux/module.h>
10#include <linux/slab.h>
11#include <linux/blkdev.h>
12#include <linux/elevator.h>
13#include <linux/jiffies.h>
14#include <linux/rbtree.h>
15#include <linux/ioprio.h>
16#include <linux/blktrace_api.h>
17#include "blk.h"
18#include "blk-cgroup.h"
19
20/*
21 * tunables
22 */
23/* max queue in one round of service */
24static const int cfq_quantum = 8;
25static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
26/* maximum backwards seek, in KiB */
27static const int cfq_back_max = 16 * 1024;
28/* penalty of a backwards seek */
29static const int cfq_back_penalty = 2;
30static const int cfq_slice_sync = HZ / 10;
31static int cfq_slice_async = HZ / 25;
32static const int cfq_slice_async_rq = 2;
33static int cfq_slice_idle = HZ / 125;
34static int cfq_group_idle = HZ / 125;
35static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
36static const int cfq_hist_divisor = 4;
37
38/*
39 * offset from end of service tree
40 */
41#define CFQ_IDLE_DELAY (HZ / 5)
42
43/*
44 * below this threshold, we consider thinktime immediate
45 */
46#define CFQ_MIN_TT (2)
47
48#define CFQ_SLICE_SCALE (5)
49#define CFQ_HW_QUEUE_MIN (5)
50#define CFQ_SERVICE_SHIFT 12
51
52#define CFQQ_SEEK_THR (sector_t)(8 * 100)
53#define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
54#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
55#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
56
57#define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
58#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
59#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
60
61static struct kmem_cache *cfq_pool;
62
63#define CFQ_PRIO_LISTS IOPRIO_BE_NR
64#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
65#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
66
67#define sample_valid(samples) ((samples) > 80)
68#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
69
70struct cfq_ttime {
71 unsigned long last_end_request;
72
73 unsigned long ttime_total;
74 unsigned long ttime_samples;
75 unsigned long ttime_mean;
76};
77
78/*
79 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
83 */
84struct cfq_rb_root {
85 struct rb_root rb;
86 struct rb_node *left;
87 unsigned count;
88 unsigned total_weight;
89 u64 min_vdisktime;
90 struct cfq_ttime ttime;
91};
92#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
93 .ttime = {.last_end_request = jiffies,},}
94
95/*
96 * Per process-grouping structure
97 */
98struct cfq_queue {
99 /* reference count */
100 int ref;
101 /* various state flags, see below */
102 unsigned int flags;
103 /* parent cfq_data */
104 struct cfq_data *cfqd;
105 /* service_tree member */
106 struct rb_node rb_node;
107 /* service_tree key */
108 unsigned long rb_key;
109 /* prio tree member */
110 struct rb_node p_node;
111 /* prio tree root we belong to, if any */
112 struct rb_root *p_root;
113 /* sorted list of pending requests */
114 struct rb_root sort_list;
115 /* if fifo isn't expired, next request to serve */
116 struct request *next_rq;
117 /* requests queued in sort_list */
118 int queued[2];
119 /* currently allocated requests */
120 int allocated[2];
121 /* fifo list of requests in sort_list */
122 struct list_head fifo;
123
124 /* time when queue got scheduled in to dispatch first request. */
125 unsigned long dispatch_start;
126 unsigned int allocated_slice;
127 unsigned int slice_dispatch;
128 /* time when first request from queue completed and slice started. */
129 unsigned long slice_start;
130 unsigned long slice_end;
131 long slice_resid;
132
133 /* pending priority requests */
134 int prio_pending;
135 /* number of requests that are on the dispatch list or inside driver */
136 int dispatched;
137
138 /* io prio of this group */
139 unsigned short ioprio, org_ioprio;
140 unsigned short ioprio_class;
141
142 pid_t pid;
143
144 u32 seek_history;
145 sector_t last_request_pos;
146
147 struct cfq_rb_root *service_tree;
148 struct cfq_queue *new_cfqq;
149 struct cfq_group *cfqg;
150 /* Number of sectors dispatched from queue in single dispatch round */
151 unsigned long nr_sectors;
152};
153
154/*
155 * First index in the service_trees.
156 * IDLE is handled separately, so it has negative index
157 */
158enum wl_prio_t {
159 BE_WORKLOAD = 0,
160 RT_WORKLOAD = 1,
161 IDLE_WORKLOAD = 2,
162 CFQ_PRIO_NR,
163};
164
165/*
166 * Second index in the service_trees.
167 */
168enum wl_type_t {
169 ASYNC_WORKLOAD = 0,
170 SYNC_NOIDLE_WORKLOAD = 1,
171 SYNC_WORKLOAD = 2
172};
173
174struct cfqg_stats {
175#ifdef CONFIG_CFQ_GROUP_IOSCHED
176 /* total bytes transferred */
177 struct blkg_rwstat service_bytes;
178 /* total IOs serviced, post merge */
179 struct blkg_rwstat serviced;
180 /* number of ios merged */
181 struct blkg_rwstat merged;
182 /* total time spent on device in ns, may not be accurate w/ queueing */
183 struct blkg_rwstat service_time;
184 /* total time spent waiting in scheduler queue in ns */
185 struct blkg_rwstat wait_time;
186 /* number of IOs queued up */
187 struct blkg_rwstat queued;
188 /* total sectors transferred */
189 struct blkg_stat sectors;
190 /* total disk time and nr sectors dispatched by this group */
191 struct blkg_stat time;
192#ifdef CONFIG_DEBUG_BLK_CGROUP
193 /* time not charged to this cgroup */
194 struct blkg_stat unaccounted_time;
195 /* sum of number of ios queued across all samples */
196 struct blkg_stat avg_queue_size_sum;
197 /* count of samples taken for average */
198 struct blkg_stat avg_queue_size_samples;
199 /* how many times this group has been removed from service tree */
200 struct blkg_stat dequeue;
201 /* total time spent waiting for it to be assigned a timeslice. */
202 struct blkg_stat group_wait_time;
203 /* time spent idling for this blkcg_gq */
204 struct blkg_stat idle_time;
205 /* total time with empty current active q with other requests queued */
206 struct blkg_stat empty_time;
207 /* fields after this shouldn't be cleared on stat reset */
208 uint64_t start_group_wait_time;
209 uint64_t start_idle_time;
210 uint64_t start_empty_time;
211 uint16_t flags;
212#endif /* CONFIG_DEBUG_BLK_CGROUP */
213#endif /* CONFIG_CFQ_GROUP_IOSCHED */
214};
215
216/* This is per cgroup per device grouping structure */
217struct cfq_group {
218 /* must be the first member */
219 struct blkg_policy_data pd;
220
221 /* group service_tree member */
222 struct rb_node rb_node;
223
224 /* group service_tree key */
225 u64 vdisktime;
226 unsigned int weight;
227 unsigned int new_weight;
228 unsigned int dev_weight;
229
230 /* number of cfqq currently on this group */
231 int nr_cfqq;
232
233 /*
234 * Per group busy queues average. Useful for workload slice calc. We
235 * create the array for each prio class but at run time it is used
236 * only for RT and BE class and slot for IDLE class remains unused.
237 * This is primarily done to avoid confusion and a gcc warning.
238 */
239 unsigned int busy_queues_avg[CFQ_PRIO_NR];
240 /*
241 * rr lists of queues with requests. We maintain service trees for
242 * RT and BE classes. These trees are subdivided in subclasses
243 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
244 * class there is no subclassification and all the cfq queues go on
245 * a single tree service_tree_idle.
246 * Counts are embedded in the cfq_rb_root
247 */
248 struct cfq_rb_root service_trees[2][3];
249 struct cfq_rb_root service_tree_idle;
250
251 unsigned long saved_workload_slice;
252 enum wl_type_t saved_workload;
253 enum wl_prio_t saved_serving_prio;
254
255 /* number of requests that are on the dispatch list or inside driver */
256 int dispatched;
257 struct cfq_ttime ttime;
258 struct cfqg_stats stats;
259};
260
261struct cfq_io_cq {
262 struct io_cq icq; /* must be the first member */
263 struct cfq_queue *cfqq[2];
264 struct cfq_ttime ttime;
265 int ioprio; /* the current ioprio */
266#ifdef CONFIG_CFQ_GROUP_IOSCHED
267 uint64_t blkcg_id; /* the current blkcg ID */
268#endif
269};
270
271/*
272 * Per block device queue structure
273 */
274struct cfq_data {
275 struct request_queue *queue;
276 /* Root service tree for cfq_groups */
277 struct cfq_rb_root grp_service_tree;
278 struct cfq_group *root_group;
279
280 /*
281 * The priority currently being served
282 */
283 enum wl_prio_t serving_prio;
284 enum wl_type_t serving_type;
285 unsigned long workload_expires;
286 struct cfq_group *serving_group;
287
288 /*
289 * Each priority tree is sorted by next_request position. These
290 * trees are used when determining if two or more queues are
291 * interleaving requests (see cfq_close_cooperator).
292 */
293 struct rb_root prio_trees[CFQ_PRIO_LISTS];
294
295 unsigned int busy_queues;
296 unsigned int busy_sync_queues;
297
298 int rq_in_driver;
299 int rq_in_flight[2];
300
301 /*
302 * queue-depth detection
303 */
304 int rq_queued;
305 int hw_tag;
306 /*
307 * hw_tag can be
308 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
309 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
310 * 0 => no NCQ
311 */
312 int hw_tag_est_depth;
313 unsigned int hw_tag_samples;
314
315 /*
316 * idle window management
317 */
318 struct timer_list idle_slice_timer;
319 struct work_struct unplug_work;
320
321 struct cfq_queue *active_queue;
322 struct cfq_io_cq *active_cic;
323
324 /*
325 * async queue for each priority case
326 */
327 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
328 struct cfq_queue *async_idle_cfqq;
329
330 sector_t last_position;
331
332 /*
333 * tunables, see top of file
334 */
335 unsigned int cfq_quantum;
336 unsigned int cfq_fifo_expire[2];
337 unsigned int cfq_back_penalty;
338 unsigned int cfq_back_max;
339 unsigned int cfq_slice[2];
340 unsigned int cfq_slice_async_rq;
341 unsigned int cfq_slice_idle;
342 unsigned int cfq_group_idle;
343 unsigned int cfq_latency;
344 unsigned int cfq_target_latency;
345
346 /*
347 * Fallback dummy cfqq for extreme OOM conditions
348 */
349 struct cfq_queue oom_cfqq;
350
351 unsigned long last_delayed_sync;
352};
353
354static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
355
356static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
357 enum wl_prio_t prio,
358 enum wl_type_t type)
359{
360 if (!cfqg)
361 return NULL;
362
363 if (prio == IDLE_WORKLOAD)
364 return &cfqg->service_tree_idle;
365
366 return &cfqg->service_trees[prio][type];
367}
368
369enum cfqq_state_flags {
370 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
371 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
372 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
373 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
374 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
375 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
376 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
377 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
378 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
379 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
380 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
381 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
382 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
383};
384
385#define CFQ_CFQQ_FNS(name) \
386static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
387{ \
388 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
389} \
390static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
391{ \
392 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
393} \
394static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
395{ \
396 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
397}
398
399CFQ_CFQQ_FNS(on_rr);
400CFQ_CFQQ_FNS(wait_request);
401CFQ_CFQQ_FNS(must_dispatch);
402CFQ_CFQQ_FNS(must_alloc_slice);
403CFQ_CFQQ_FNS(fifo_expire);
404CFQ_CFQQ_FNS(idle_window);
405CFQ_CFQQ_FNS(prio_changed);
406CFQ_CFQQ_FNS(slice_new);
407CFQ_CFQQ_FNS(sync);
408CFQ_CFQQ_FNS(coop);
409CFQ_CFQQ_FNS(split_coop);
410CFQ_CFQQ_FNS(deep);
411CFQ_CFQQ_FNS(wait_busy);
412#undef CFQ_CFQQ_FNS
413
414static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
415{
416 return pd ? container_of(pd, struct cfq_group, pd) : NULL;
417}
418
419static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
420{
421 return pd_to_blkg(&cfqg->pd);
422}
423
424#if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
425
426/* cfqg stats flags */
427enum cfqg_stats_flags {
428 CFQG_stats_waiting = 0,
429 CFQG_stats_idling,
430 CFQG_stats_empty,
431};
432
433#define CFQG_FLAG_FNS(name) \
434static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
435{ \
436 stats->flags |= (1 << CFQG_stats_##name); \
437} \
438static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
439{ \
440 stats->flags &= ~(1 << CFQG_stats_##name); \
441} \
442static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
443{ \
444 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
445} \
446
447CFQG_FLAG_FNS(waiting)
448CFQG_FLAG_FNS(idling)
449CFQG_FLAG_FNS(empty)
450#undef CFQG_FLAG_FNS
451
452/* This should be called with the queue_lock held. */
453static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
454{
455 unsigned long long now;
456
457 if (!cfqg_stats_waiting(stats))
458 return;
459
460 now = sched_clock();
461 if (time_after64(now, stats->start_group_wait_time))
462 blkg_stat_add(&stats->group_wait_time,
463 now - stats->start_group_wait_time);
464 cfqg_stats_clear_waiting(stats);
465}
466
467/* This should be called with the queue_lock held. */
468static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
469 struct cfq_group *curr_cfqg)
470{
471 struct cfqg_stats *stats = &cfqg->stats;
472
473 if (cfqg_stats_waiting(stats))
474 return;
475 if (cfqg == curr_cfqg)
476 return;
477 stats->start_group_wait_time = sched_clock();
478 cfqg_stats_mark_waiting(stats);
479}
480
481/* This should be called with the queue_lock held. */
482static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
483{
484 unsigned long long now;
485
486 if (!cfqg_stats_empty(stats))
487 return;
488
489 now = sched_clock();
490 if (time_after64(now, stats->start_empty_time))
491 blkg_stat_add(&stats->empty_time,
492 now - stats->start_empty_time);
493 cfqg_stats_clear_empty(stats);
494}
495
496static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
497{
498 blkg_stat_add(&cfqg->stats.dequeue, 1);
499}
500
501static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
502{
503 struct cfqg_stats *stats = &cfqg->stats;
504
505 if (blkg_rwstat_sum(&stats->queued))
506 return;
507
508 /*
509 * group is already marked empty. This can happen if cfqq got new
510 * request in parent group and moved to this group while being added
511 * to service tree. Just ignore the event and move on.
512 */
513 if (cfqg_stats_empty(stats))
514 return;
515
516 stats->start_empty_time = sched_clock();
517 cfqg_stats_mark_empty(stats);
518}
519
520static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
521{
522 struct cfqg_stats *stats = &cfqg->stats;
523
524 if (cfqg_stats_idling(stats)) {
525 unsigned long long now = sched_clock();
526
527 if (time_after64(now, stats->start_idle_time))
528 blkg_stat_add(&stats->idle_time,
529 now - stats->start_idle_time);
530 cfqg_stats_clear_idling(stats);
531 }
532}
533
534static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
535{
536 struct cfqg_stats *stats = &cfqg->stats;
537
538 BUG_ON(cfqg_stats_idling(stats));
539
540 stats->start_idle_time = sched_clock();
541 cfqg_stats_mark_idling(stats);
542}
543
544static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
545{
546 struct cfqg_stats *stats = &cfqg->stats;
547
548 blkg_stat_add(&stats->avg_queue_size_sum,
549 blkg_rwstat_sum(&stats->queued));
550 blkg_stat_add(&stats->avg_queue_size_samples, 1);
551 cfqg_stats_update_group_wait_time(stats);
552}
553
554#else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
555
556static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
557static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
558static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
559static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
560static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
561static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
562static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
563
564#endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
565
566#ifdef CONFIG_CFQ_GROUP_IOSCHED
567
568static struct blkcg_policy blkcg_policy_cfq;
569
570static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
571{
572 return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
573}
574
575static inline void cfqg_get(struct cfq_group *cfqg)
576{
577 return blkg_get(cfqg_to_blkg(cfqg));
578}
579
580static inline void cfqg_put(struct cfq_group *cfqg)
581{
582 return blkg_put(cfqg_to_blkg(cfqg));
583}
584
585#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
586 char __pbuf[128]; \
587 \
588 blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \
589 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
590 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
591 __pbuf, ##args); \
592} while (0)
593
594#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
595 char __pbuf[128]; \
596 \
597 blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \
598 blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \
599} while (0)
600
601static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
602 struct cfq_group *curr_cfqg, int rw)
603{
604 blkg_rwstat_add(&cfqg->stats.queued, rw, 1);
605 cfqg_stats_end_empty_time(&cfqg->stats);
606 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
607}
608
609static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
610 unsigned long time, unsigned long unaccounted_time)
611{
612 blkg_stat_add(&cfqg->stats.time, time);
613#ifdef CONFIG_DEBUG_BLK_CGROUP
614 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
615#endif
616}
617
618static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw)
619{
620 blkg_rwstat_add(&cfqg->stats.queued, rw, -1);
621}
622
623static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
624{
625 blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
626}
627
628static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
629 uint64_t bytes, int rw)
630{
631 blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
632 blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
633 blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
634}
635
636static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
637 uint64_t start_time, uint64_t io_start_time, int rw)
638{
639 struct cfqg_stats *stats = &cfqg->stats;
640 unsigned long long now = sched_clock();
641
642 if (time_after64(now, io_start_time))
643 blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
644 if (time_after64(io_start_time, start_time))
645 blkg_rwstat_add(&stats->wait_time, rw,
646 io_start_time - start_time);
647}
648
649static void cfq_pd_reset_stats(struct blkcg_gq *blkg)
650{
651 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
652 struct cfqg_stats *stats = &cfqg->stats;
653
654 /* queued stats shouldn't be cleared */
655 blkg_rwstat_reset(&stats->service_bytes);
656 blkg_rwstat_reset(&stats->serviced);
657 blkg_rwstat_reset(&stats->merged);
658 blkg_rwstat_reset(&stats->service_time);
659 blkg_rwstat_reset(&stats->wait_time);
660 blkg_stat_reset(&stats->time);
661#ifdef CONFIG_DEBUG_BLK_CGROUP
662 blkg_stat_reset(&stats->unaccounted_time);
663 blkg_stat_reset(&stats->avg_queue_size_sum);
664 blkg_stat_reset(&stats->avg_queue_size_samples);
665 blkg_stat_reset(&stats->dequeue);
666 blkg_stat_reset(&stats->group_wait_time);
667 blkg_stat_reset(&stats->idle_time);
668 blkg_stat_reset(&stats->empty_time);
669#endif
670}
671
672#else /* CONFIG_CFQ_GROUP_IOSCHED */
673
674static inline void cfqg_get(struct cfq_group *cfqg) { }
675static inline void cfqg_put(struct cfq_group *cfqg) { }
676
677#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
678 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
679#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
680
681static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
682 struct cfq_group *curr_cfqg, int rw) { }
683static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
684 unsigned long time, unsigned long unaccounted_time) { }
685static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
686static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
687static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
688 uint64_t bytes, int rw) { }
689static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
690 uint64_t start_time, uint64_t io_start_time, int rw) { }
691
692#endif /* CONFIG_CFQ_GROUP_IOSCHED */
693
694#define cfq_log(cfqd, fmt, args...) \
695 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
696
697/* Traverses through cfq group service trees */
698#define for_each_cfqg_st(cfqg, i, j, st) \
699 for (i = 0; i <= IDLE_WORKLOAD; i++) \
700 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
701 : &cfqg->service_tree_idle; \
702 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
703 (i == IDLE_WORKLOAD && j == 0); \
704 j++, st = i < IDLE_WORKLOAD ? \
705 &cfqg->service_trees[i][j]: NULL) \
706
707static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
708 struct cfq_ttime *ttime, bool group_idle)
709{
710 unsigned long slice;
711 if (!sample_valid(ttime->ttime_samples))
712 return false;
713 if (group_idle)
714 slice = cfqd->cfq_group_idle;
715 else
716 slice = cfqd->cfq_slice_idle;
717 return ttime->ttime_mean > slice;
718}
719
720static inline bool iops_mode(struct cfq_data *cfqd)
721{
722 /*
723 * If we are not idling on queues and it is a NCQ drive, parallel
724 * execution of requests is on and measuring time is not possible
725 * in most of the cases until and unless we drive shallower queue
726 * depths and that becomes a performance bottleneck. In such cases
727 * switch to start providing fairness in terms of number of IOs.
728 */
729 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
730 return true;
731 else
732 return false;
733}
734
735static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
736{
737 if (cfq_class_idle(cfqq))
738 return IDLE_WORKLOAD;
739 if (cfq_class_rt(cfqq))
740 return RT_WORKLOAD;
741 return BE_WORKLOAD;
742}
743
744
745static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
746{
747 if (!cfq_cfqq_sync(cfqq))
748 return ASYNC_WORKLOAD;
749 if (!cfq_cfqq_idle_window(cfqq))
750 return SYNC_NOIDLE_WORKLOAD;
751 return SYNC_WORKLOAD;
752}
753
754static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
755 struct cfq_data *cfqd,
756 struct cfq_group *cfqg)
757{
758 if (wl == IDLE_WORKLOAD)
759 return cfqg->service_tree_idle.count;
760
761 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
762 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
763 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
764}
765
766static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
767 struct cfq_group *cfqg)
768{
769 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
770 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
771}
772
773static void cfq_dispatch_insert(struct request_queue *, struct request *);
774static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
775 struct cfq_io_cq *cic, struct bio *bio,
776 gfp_t gfp_mask);
777
778static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
779{
780 /* cic->icq is the first member, %NULL will convert to %NULL */
781 return container_of(icq, struct cfq_io_cq, icq);
782}
783
784static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
785 struct io_context *ioc)
786{
787 if (ioc)
788 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
789 return NULL;
790}
791
792static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
793{
794 return cic->cfqq[is_sync];
795}
796
797static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
798 bool is_sync)
799{
800 cic->cfqq[is_sync] = cfqq;
801}
802
803static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
804{
805 return cic->icq.q->elevator->elevator_data;
806}
807
808/*
809 * We regard a request as SYNC, if it's either a read or has the SYNC bit
810 * set (in which case it could also be direct WRITE).
811 */
812static inline bool cfq_bio_sync(struct bio *bio)
813{
814 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
815}
816
817/*
818 * scheduler run of queue, if there are requests pending and no one in the
819 * driver that will restart queueing
820 */
821static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
822{
823 if (cfqd->busy_queues) {
824 cfq_log(cfqd, "schedule dispatch");
825 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
826 }
827}
828
829/*
830 * Scale schedule slice based on io priority. Use the sync time slice only
831 * if a queue is marked sync and has sync io queued. A sync queue with async
832 * io only, should not get full sync slice length.
833 */
834static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
835 unsigned short prio)
836{
837 const int base_slice = cfqd->cfq_slice[sync];
838
839 WARN_ON(prio >= IOPRIO_BE_NR);
840
841 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
842}
843
844static inline int
845cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
846{
847 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
848}
849
850static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
851{
852 u64 d = delta << CFQ_SERVICE_SHIFT;
853
854 d = d * CFQ_WEIGHT_DEFAULT;
855 do_div(d, cfqg->weight);
856 return d;
857}
858
859static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
860{
861 s64 delta = (s64)(vdisktime - min_vdisktime);
862 if (delta > 0)
863 min_vdisktime = vdisktime;
864
865 return min_vdisktime;
866}
867
868static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
869{
870 s64 delta = (s64)(vdisktime - min_vdisktime);
871 if (delta < 0)
872 min_vdisktime = vdisktime;
873
874 return min_vdisktime;
875}
876
877static void update_min_vdisktime(struct cfq_rb_root *st)
878{
879 struct cfq_group *cfqg;
880
881 if (st->left) {
882 cfqg = rb_entry_cfqg(st->left);
883 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
884 cfqg->vdisktime);
885 }
886}
887
888/*
889 * get averaged number of queues of RT/BE priority.
890 * average is updated, with a formula that gives more weight to higher numbers,
891 * to quickly follows sudden increases and decrease slowly
892 */
893
894static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
895 struct cfq_group *cfqg, bool rt)
896{
897 unsigned min_q, max_q;
898 unsigned mult = cfq_hist_divisor - 1;
899 unsigned round = cfq_hist_divisor / 2;
900 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
901
902 min_q = min(cfqg->busy_queues_avg[rt], busy);
903 max_q = max(cfqg->busy_queues_avg[rt], busy);
904 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
905 cfq_hist_divisor;
906 return cfqg->busy_queues_avg[rt];
907}
908
909static inline unsigned
910cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
911{
912 struct cfq_rb_root *st = &cfqd->grp_service_tree;
913
914 return cfqd->cfq_target_latency * cfqg->weight / st->total_weight;
915}
916
917static inline unsigned
918cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
919{
920 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
921 if (cfqd->cfq_latency) {
922 /*
923 * interested queues (we consider only the ones with the same
924 * priority class in the cfq group)
925 */
926 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
927 cfq_class_rt(cfqq));
928 unsigned sync_slice = cfqd->cfq_slice[1];
929 unsigned expect_latency = sync_slice * iq;
930 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
931
932 if (expect_latency > group_slice) {
933 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
934 /* scale low_slice according to IO priority
935 * and sync vs async */
936 unsigned low_slice =
937 min(slice, base_low_slice * slice / sync_slice);
938 /* the adapted slice value is scaled to fit all iqs
939 * into the target latency */
940 slice = max(slice * group_slice / expect_latency,
941 low_slice);
942 }
943 }
944 return slice;
945}
946
947static inline void
948cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
949{
950 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
951
952 cfqq->slice_start = jiffies;
953 cfqq->slice_end = jiffies + slice;
954 cfqq->allocated_slice = slice;
955 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
956}
957
958/*
959 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
960 * isn't valid until the first request from the dispatch is activated
961 * and the slice time set.
962 */
963static inline bool cfq_slice_used(struct cfq_queue *cfqq)
964{
965 if (cfq_cfqq_slice_new(cfqq))
966 return false;
967 if (time_before(jiffies, cfqq->slice_end))
968 return false;
969
970 return true;
971}
972
973/*
974 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
975 * We choose the request that is closest to the head right now. Distance
976 * behind the head is penalized and only allowed to a certain extent.
977 */
978static struct request *
979cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
980{
981 sector_t s1, s2, d1 = 0, d2 = 0;
982 unsigned long back_max;
983#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
984#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
985 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
986
987 if (rq1 == NULL || rq1 == rq2)
988 return rq2;
989 if (rq2 == NULL)
990 return rq1;
991
992 if (rq_is_sync(rq1) != rq_is_sync(rq2))
993 return rq_is_sync(rq1) ? rq1 : rq2;
994
995 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
996 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
997
998 s1 = blk_rq_pos(rq1);
999 s2 = blk_rq_pos(rq2);
1000
1001 /*
1002 * by definition, 1KiB is 2 sectors
1003 */
1004 back_max = cfqd->cfq_back_max * 2;
1005
1006 /*
1007 * Strict one way elevator _except_ in the case where we allow
1008 * short backward seeks which are biased as twice the cost of a
1009 * similar forward seek.
1010 */
1011 if (s1 >= last)
1012 d1 = s1 - last;
1013 else if (s1 + back_max >= last)
1014 d1 = (last - s1) * cfqd->cfq_back_penalty;
1015 else
1016 wrap |= CFQ_RQ1_WRAP;
1017
1018 if (s2 >= last)
1019 d2 = s2 - last;
1020 else if (s2 + back_max >= last)
1021 d2 = (last - s2) * cfqd->cfq_back_penalty;
1022 else
1023 wrap |= CFQ_RQ2_WRAP;
1024
1025 /* Found required data */
1026
1027 /*
1028 * By doing switch() on the bit mask "wrap" we avoid having to
1029 * check two variables for all permutations: --> faster!
1030 */
1031 switch (wrap) {
1032 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1033 if (d1 < d2)
1034 return rq1;
1035 else if (d2 < d1)
1036 return rq2;
1037 else {
1038 if (s1 >= s2)
1039 return rq1;
1040 else
1041 return rq2;
1042 }
1043
1044 case CFQ_RQ2_WRAP:
1045 return rq1;
1046 case CFQ_RQ1_WRAP:
1047 return rq2;
1048 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1049 default:
1050 /*
1051 * Since both rqs are wrapped,
1052 * start with the one that's further behind head
1053 * (--> only *one* back seek required),
1054 * since back seek takes more time than forward.
1055 */
1056 if (s1 <= s2)
1057 return rq1;
1058 else
1059 return rq2;
1060 }
1061}
1062
1063/*
1064 * The below is leftmost cache rbtree addon
1065 */
1066static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1067{
1068 /* Service tree is empty */
1069 if (!root->count)
1070 return NULL;
1071
1072 if (!root->left)
1073 root->left = rb_first(&root->rb);
1074
1075 if (root->left)
1076 return rb_entry(root->left, struct cfq_queue, rb_node);
1077
1078 return NULL;
1079}
1080
1081static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1082{
1083 if (!root->left)
1084 root->left = rb_first(&root->rb);
1085
1086 if (root->left)
1087 return rb_entry_cfqg(root->left);
1088
1089 return NULL;
1090}
1091
1092static void rb_erase_init(struct rb_node *n, struct rb_root *root)
1093{
1094 rb_erase(n, root);
1095 RB_CLEAR_NODE(n);
1096}
1097
1098static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1099{
1100 if (root->left == n)
1101 root->left = NULL;
1102 rb_erase_init(n, &root->rb);
1103 --root->count;
1104}
1105
1106/*
1107 * would be nice to take fifo expire time into account as well
1108 */
1109static struct request *
1110cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1111 struct request *last)
1112{
1113 struct rb_node *rbnext = rb_next(&last->rb_node);
1114 struct rb_node *rbprev = rb_prev(&last->rb_node);
1115 struct request *next = NULL, *prev = NULL;
1116
1117 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1118
1119 if (rbprev)
1120 prev = rb_entry_rq(rbprev);
1121
1122 if (rbnext)
1123 next = rb_entry_rq(rbnext);
1124 else {
1125 rbnext = rb_first(&cfqq->sort_list);
1126 if (rbnext && rbnext != &last->rb_node)
1127 next = rb_entry_rq(rbnext);
1128 }
1129
1130 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1131}
1132
1133static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
1134 struct cfq_queue *cfqq)
1135{
1136 /*
1137 * just an approximation, should be ok.
1138 */
1139 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1140 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1141}
1142
1143static inline s64
1144cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1145{
1146 return cfqg->vdisktime - st->min_vdisktime;
1147}
1148
1149static void
1150__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1151{
1152 struct rb_node **node = &st->rb.rb_node;
1153 struct rb_node *parent = NULL;
1154 struct cfq_group *__cfqg;
1155 s64 key = cfqg_key(st, cfqg);
1156 int left = 1;
1157
1158 while (*node != NULL) {
1159 parent = *node;
1160 __cfqg = rb_entry_cfqg(parent);
1161
1162 if (key < cfqg_key(st, __cfqg))
1163 node = &parent->rb_left;
1164 else {
1165 node = &parent->rb_right;
1166 left = 0;
1167 }
1168 }
1169
1170 if (left)
1171 st->left = &cfqg->rb_node;
1172
1173 rb_link_node(&cfqg->rb_node, parent, node);
1174 rb_insert_color(&cfqg->rb_node, &st->rb);
1175}
1176
1177static void
1178cfq_update_group_weight(struct cfq_group *cfqg)
1179{
1180 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1181 if (cfqg->new_weight) {
1182 cfqg->weight = cfqg->new_weight;
1183 cfqg->new_weight = 0;
1184 }
1185}
1186
1187static void
1188cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1189{
1190 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1191
1192 cfq_update_group_weight(cfqg);
1193 __cfq_group_service_tree_add(st, cfqg);
1194 st->total_weight += cfqg->weight;
1195}
1196
1197static void
1198cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1199{
1200 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1201 struct cfq_group *__cfqg;
1202 struct rb_node *n;
1203
1204 cfqg->nr_cfqq++;
1205 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1206 return;
1207
1208 /*
1209 * Currently put the group at the end. Later implement something
1210 * so that groups get lesser vtime based on their weights, so that
1211 * if group does not loose all if it was not continuously backlogged.
1212 */
1213 n = rb_last(&st->rb);
1214 if (n) {
1215 __cfqg = rb_entry_cfqg(n);
1216 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1217 } else
1218 cfqg->vdisktime = st->min_vdisktime;
1219 cfq_group_service_tree_add(st, cfqg);
1220}
1221
1222static void
1223cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1224{
1225 st->total_weight -= cfqg->weight;
1226 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1227 cfq_rb_erase(&cfqg->rb_node, st);
1228}
1229
1230static void
1231cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1232{
1233 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1234
1235 BUG_ON(cfqg->nr_cfqq < 1);
1236 cfqg->nr_cfqq--;
1237
1238 /* If there are other cfq queues under this group, don't delete it */
1239 if (cfqg->nr_cfqq)
1240 return;
1241
1242 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1243 cfq_group_service_tree_del(st, cfqg);
1244 cfqg->saved_workload_slice = 0;
1245 cfqg_stats_update_dequeue(cfqg);
1246}
1247
1248static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1249 unsigned int *unaccounted_time)
1250{
1251 unsigned int slice_used;
1252
1253 /*
1254 * Queue got expired before even a single request completed or
1255 * got expired immediately after first request completion.
1256 */
1257 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
1258 /*
1259 * Also charge the seek time incurred to the group, otherwise
1260 * if there are mutiple queues in the group, each can dispatch
1261 * a single request on seeky media and cause lots of seek time
1262 * and group will never know it.
1263 */
1264 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1265 1);
1266 } else {
1267 slice_used = jiffies - cfqq->slice_start;
1268 if (slice_used > cfqq->allocated_slice) {
1269 *unaccounted_time = slice_used - cfqq->allocated_slice;
1270 slice_used = cfqq->allocated_slice;
1271 }
1272 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
1273 *unaccounted_time += cfqq->slice_start -
1274 cfqq->dispatch_start;
1275 }
1276
1277 return slice_used;
1278}
1279
1280static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1281 struct cfq_queue *cfqq)
1282{
1283 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1284 unsigned int used_sl, charge, unaccounted_sl = 0;
1285 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1286 - cfqg->service_tree_idle.count;
1287
1288 BUG_ON(nr_sync < 0);
1289 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1290
1291 if (iops_mode(cfqd))
1292 charge = cfqq->slice_dispatch;
1293 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1294 charge = cfqq->allocated_slice;
1295
1296 /* Can't update vdisktime while group is on service tree */
1297 cfq_group_service_tree_del(st, cfqg);
1298 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
1299 /* If a new weight was requested, update now, off tree */
1300 cfq_group_service_tree_add(st, cfqg);
1301
1302 /* This group is being expired. Save the context */
1303 if (time_after(cfqd->workload_expires, jiffies)) {
1304 cfqg->saved_workload_slice = cfqd->workload_expires
1305 - jiffies;
1306 cfqg->saved_workload = cfqd->serving_type;
1307 cfqg->saved_serving_prio = cfqd->serving_prio;
1308 } else
1309 cfqg->saved_workload_slice = 0;
1310
1311 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1312 st->min_vdisktime);
1313 cfq_log_cfqq(cfqq->cfqd, cfqq,
1314 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1315 used_sl, cfqq->slice_dispatch, charge,
1316 iops_mode(cfqd), cfqq->nr_sectors);
1317 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1318 cfqg_stats_set_start_empty_time(cfqg);
1319}
1320
1321/**
1322 * cfq_init_cfqg_base - initialize base part of a cfq_group
1323 * @cfqg: cfq_group to initialize
1324 *
1325 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1326 * is enabled or not.
1327 */
1328static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1329{
1330 struct cfq_rb_root *st;
1331 int i, j;
1332
1333 for_each_cfqg_st(cfqg, i, j, st)
1334 *st = CFQ_RB_ROOT;
1335 RB_CLEAR_NODE(&cfqg->rb_node);
1336
1337 cfqg->ttime.last_end_request = jiffies;
1338}
1339
1340#ifdef CONFIG_CFQ_GROUP_IOSCHED
1341static void cfq_pd_init(struct blkcg_gq *blkg)
1342{
1343 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1344
1345 cfq_init_cfqg_base(cfqg);
1346 cfqg->weight = blkg->blkcg->cfq_weight;
1347}
1348
1349/*
1350 * Search for the cfq group current task belongs to. request_queue lock must
1351 * be held.
1352 */
1353static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1354 struct blkcg *blkcg)
1355{
1356 struct request_queue *q = cfqd->queue;
1357 struct cfq_group *cfqg = NULL;
1358
1359 /* avoid lookup for the common case where there's no blkcg */
1360 if (blkcg == &blkcg_root) {
1361 cfqg = cfqd->root_group;
1362 } else {
1363 struct blkcg_gq *blkg;
1364
1365 blkg = blkg_lookup_create(blkcg, q);
1366 if (!IS_ERR(blkg))
1367 cfqg = blkg_to_cfqg(blkg);
1368 }
1369
1370 return cfqg;
1371}
1372
1373static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1374{
1375 /* Currently, all async queues are mapped to root group */
1376 if (!cfq_cfqq_sync(cfqq))
1377 cfqg = cfqq->cfqd->root_group;
1378
1379 cfqq->cfqg = cfqg;
1380 /* cfqq reference on cfqg */
1381 cfqg_get(cfqg);
1382}
1383
1384static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1385 struct blkg_policy_data *pd, int off)
1386{
1387 struct cfq_group *cfqg = pd_to_cfqg(pd);
1388
1389 if (!cfqg->dev_weight)
1390 return 0;
1391 return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1392}
1393
1394static int cfqg_print_weight_device(struct cgroup *cgrp, struct cftype *cft,
1395 struct seq_file *sf)
1396{
1397 blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp),
1398 cfqg_prfill_weight_device, &blkcg_policy_cfq, 0,
1399 false);
1400 return 0;
1401}
1402
1403static int cfq_print_weight(struct cgroup *cgrp, struct cftype *cft,
1404 struct seq_file *sf)
1405{
1406 seq_printf(sf, "%u\n", cgroup_to_blkcg(cgrp)->cfq_weight);
1407 return 0;
1408}
1409
1410static int cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft,
1411 const char *buf)
1412{
1413 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1414 struct blkg_conf_ctx ctx;
1415 struct cfq_group *cfqg;
1416 int ret;
1417
1418 ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1419 if (ret)
1420 return ret;
1421
1422 ret = -EINVAL;
1423 cfqg = blkg_to_cfqg(ctx.blkg);
1424 if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
1425 cfqg->dev_weight = ctx.v;
1426 cfqg->new_weight = cfqg->dev_weight ?: blkcg->cfq_weight;
1427 ret = 0;
1428 }
1429
1430 blkg_conf_finish(&ctx);
1431 return ret;
1432}
1433
1434static int cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val)
1435{
1436 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1437 struct blkcg_gq *blkg;
1438 struct hlist_node *n;
1439
1440 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
1441 return -EINVAL;
1442
1443 spin_lock_irq(&blkcg->lock);
1444 blkcg->cfq_weight = (unsigned int)val;
1445
1446 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1447 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1448
1449 if (cfqg && !cfqg->dev_weight)
1450 cfqg->new_weight = blkcg->cfq_weight;
1451 }
1452
1453 spin_unlock_irq(&blkcg->lock);
1454 return 0;
1455}
1456
1457static int cfqg_print_stat(struct cgroup *cgrp, struct cftype *cft,
1458 struct seq_file *sf)
1459{
1460 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1461
1462 blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat, &blkcg_policy_cfq,
1463 cft->private, false);
1464 return 0;
1465}
1466
1467static int cfqg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,
1468 struct seq_file *sf)
1469{
1470 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1471
1472 blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat, &blkcg_policy_cfq,
1473 cft->private, true);
1474 return 0;
1475}
1476
1477#ifdef CONFIG_DEBUG_BLK_CGROUP
1478static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1479 struct blkg_policy_data *pd, int off)
1480{
1481 struct cfq_group *cfqg = pd_to_cfqg(pd);
1482 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1483 u64 v = 0;
1484
1485 if (samples) {
1486 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1487 do_div(v, samples);
1488 }
1489 __blkg_prfill_u64(sf, pd, v);
1490 return 0;
1491}
1492
1493/* print avg_queue_size */
1494static int cfqg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft,
1495 struct seq_file *sf)
1496{
1497 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1498
1499 blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size,
1500 &blkcg_policy_cfq, 0, false);
1501 return 0;
1502}
1503#endif /* CONFIG_DEBUG_BLK_CGROUP */
1504
1505static struct cftype cfq_blkcg_files[] = {
1506 {
1507 .name = "weight_device",
1508 .read_seq_string = cfqg_print_weight_device,
1509 .write_string = cfqg_set_weight_device,
1510 .max_write_len = 256,
1511 },
1512 {
1513 .name = "weight",
1514 .read_seq_string = cfq_print_weight,
1515 .write_u64 = cfq_set_weight,
1516 },
1517 {
1518 .name = "time",
1519 .private = offsetof(struct cfq_group, stats.time),
1520 .read_seq_string = cfqg_print_stat,
1521 },
1522 {
1523 .name = "sectors",
1524 .private = offsetof(struct cfq_group, stats.sectors),
1525 .read_seq_string = cfqg_print_stat,
1526 },
1527 {
1528 .name = "io_service_bytes",
1529 .private = offsetof(struct cfq_group, stats.service_bytes),
1530 .read_seq_string = cfqg_print_rwstat,
1531 },
1532 {
1533 .name = "io_serviced",
1534 .private = offsetof(struct cfq_group, stats.serviced),
1535 .read_seq_string = cfqg_print_rwstat,
1536 },
1537 {
1538 .name = "io_service_time",
1539 .private = offsetof(struct cfq_group, stats.service_time),
1540 .read_seq_string = cfqg_print_rwstat,
1541 },
1542 {
1543 .name = "io_wait_time",
1544 .private = offsetof(struct cfq_group, stats.wait_time),
1545 .read_seq_string = cfqg_print_rwstat,
1546 },
1547 {
1548 .name = "io_merged",
1549 .private = offsetof(struct cfq_group, stats.merged),
1550 .read_seq_string = cfqg_print_rwstat,
1551 },
1552 {
1553 .name = "io_queued",
1554 .private = offsetof(struct cfq_group, stats.queued),
1555 .read_seq_string = cfqg_print_rwstat,
1556 },
1557#ifdef CONFIG_DEBUG_BLK_CGROUP
1558 {
1559 .name = "avg_queue_size",
1560 .read_seq_string = cfqg_print_avg_queue_size,
1561 },
1562 {
1563 .name = "group_wait_time",
1564 .private = offsetof(struct cfq_group, stats.group_wait_time),
1565 .read_seq_string = cfqg_print_stat,
1566 },
1567 {
1568 .name = "idle_time",
1569 .private = offsetof(struct cfq_group, stats.idle_time),
1570 .read_seq_string = cfqg_print_stat,
1571 },
1572 {
1573 .name = "empty_time",
1574 .private = offsetof(struct cfq_group, stats.empty_time),
1575 .read_seq_string = cfqg_print_stat,
1576 },
1577 {
1578 .name = "dequeue",
1579 .private = offsetof(struct cfq_group, stats.dequeue),
1580 .read_seq_string = cfqg_print_stat,
1581 },
1582 {
1583 .name = "unaccounted_time",
1584 .private = offsetof(struct cfq_group, stats.unaccounted_time),
1585 .read_seq_string = cfqg_print_stat,
1586 },
1587#endif /* CONFIG_DEBUG_BLK_CGROUP */
1588 { } /* terminate */
1589};
1590#else /* GROUP_IOSCHED */
1591static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1592 struct blkcg *blkcg)
1593{
1594 return cfqd->root_group;
1595}
1596
1597static inline void
1598cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1599 cfqq->cfqg = cfqg;
1600}
1601
1602#endif /* GROUP_IOSCHED */
1603
1604/*
1605 * The cfqd->service_trees holds all pending cfq_queue's that have
1606 * requests waiting to be processed. It is sorted in the order that
1607 * we will service the queues.
1608 */
1609static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1610 bool add_front)
1611{
1612 struct rb_node **p, *parent;
1613 struct cfq_queue *__cfqq;
1614 unsigned long rb_key;
1615 struct cfq_rb_root *service_tree;
1616 int left;
1617 int new_cfqq = 1;
1618
1619 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1620 cfqq_type(cfqq));
1621 if (cfq_class_idle(cfqq)) {
1622 rb_key = CFQ_IDLE_DELAY;
1623 parent = rb_last(&service_tree->rb);
1624 if (parent && parent != &cfqq->rb_node) {
1625 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1626 rb_key += __cfqq->rb_key;
1627 } else
1628 rb_key += jiffies;
1629 } else if (!add_front) {
1630 /*
1631 * Get our rb key offset. Subtract any residual slice
1632 * value carried from last service. A negative resid
1633 * count indicates slice overrun, and this should position
1634 * the next service time further away in the tree.
1635 */
1636 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1637 rb_key -= cfqq->slice_resid;
1638 cfqq->slice_resid = 0;
1639 } else {
1640 rb_key = -HZ;
1641 __cfqq = cfq_rb_first(service_tree);
1642 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1643 }
1644
1645 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1646 new_cfqq = 0;
1647 /*
1648 * same position, nothing more to do
1649 */
1650 if (rb_key == cfqq->rb_key &&
1651 cfqq->service_tree == service_tree)
1652 return;
1653
1654 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1655 cfqq->service_tree = NULL;
1656 }
1657
1658 left = 1;
1659 parent = NULL;
1660 cfqq->service_tree = service_tree;
1661 p = &service_tree->rb.rb_node;
1662 while (*p) {
1663 struct rb_node **n;
1664
1665 parent = *p;
1666 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1667
1668 /*
1669 * sort by key, that represents service time.
1670 */
1671 if (time_before(rb_key, __cfqq->rb_key))
1672 n = &(*p)->rb_left;
1673 else {
1674 n = &(*p)->rb_right;
1675 left = 0;
1676 }
1677
1678 p = n;
1679 }
1680
1681 if (left)
1682 service_tree->left = &cfqq->rb_node;
1683
1684 cfqq->rb_key = rb_key;
1685 rb_link_node(&cfqq->rb_node, parent, p);
1686 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1687 service_tree->count++;
1688 if (add_front || !new_cfqq)
1689 return;
1690 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
1691}
1692
1693static struct cfq_queue *
1694cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1695 sector_t sector, struct rb_node **ret_parent,
1696 struct rb_node ***rb_link)
1697{
1698 struct rb_node **p, *parent;
1699 struct cfq_queue *cfqq = NULL;
1700
1701 parent = NULL;
1702 p = &root->rb_node;
1703 while (*p) {
1704 struct rb_node **n;
1705
1706 parent = *p;
1707 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1708
1709 /*
1710 * Sort strictly based on sector. Smallest to the left,
1711 * largest to the right.
1712 */
1713 if (sector > blk_rq_pos(cfqq->next_rq))
1714 n = &(*p)->rb_right;
1715 else if (sector < blk_rq_pos(cfqq->next_rq))
1716 n = &(*p)->rb_left;
1717 else
1718 break;
1719 p = n;
1720 cfqq = NULL;
1721 }
1722
1723 *ret_parent = parent;
1724 if (rb_link)
1725 *rb_link = p;
1726 return cfqq;
1727}
1728
1729static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1730{
1731 struct rb_node **p, *parent;
1732 struct cfq_queue *__cfqq;
1733
1734 if (cfqq->p_root) {
1735 rb_erase(&cfqq->p_node, cfqq->p_root);
1736 cfqq->p_root = NULL;
1737 }
1738
1739 if (cfq_class_idle(cfqq))
1740 return;
1741 if (!cfqq->next_rq)
1742 return;
1743
1744 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1745 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1746 blk_rq_pos(cfqq->next_rq), &parent, &p);
1747 if (!__cfqq) {
1748 rb_link_node(&cfqq->p_node, parent, p);
1749 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1750 } else
1751 cfqq->p_root = NULL;
1752}
1753
1754/*
1755 * Update cfqq's position in the service tree.
1756 */
1757static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1758{
1759 /*
1760 * Resorting requires the cfqq to be on the RR list already.
1761 */
1762 if (cfq_cfqq_on_rr(cfqq)) {
1763 cfq_service_tree_add(cfqd, cfqq, 0);
1764 cfq_prio_tree_add(cfqd, cfqq);
1765 }
1766}
1767
1768/*
1769 * add to busy list of queues for service, trying to be fair in ordering
1770 * the pending list according to last request service
1771 */
1772static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1773{
1774 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1775 BUG_ON(cfq_cfqq_on_rr(cfqq));
1776 cfq_mark_cfqq_on_rr(cfqq);
1777 cfqd->busy_queues++;
1778 if (cfq_cfqq_sync(cfqq))
1779 cfqd->busy_sync_queues++;
1780
1781 cfq_resort_rr_list(cfqd, cfqq);
1782}
1783
1784/*
1785 * Called when the cfqq no longer has requests pending, remove it from
1786 * the service tree.
1787 */
1788static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1789{
1790 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1791 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1792 cfq_clear_cfqq_on_rr(cfqq);
1793
1794 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1795 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1796 cfqq->service_tree = NULL;
1797 }
1798 if (cfqq->p_root) {
1799 rb_erase(&cfqq->p_node, cfqq->p_root);
1800 cfqq->p_root = NULL;
1801 }
1802
1803 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1804 BUG_ON(!cfqd->busy_queues);
1805 cfqd->busy_queues--;
1806 if (cfq_cfqq_sync(cfqq))
1807 cfqd->busy_sync_queues--;
1808}
1809
1810/*
1811 * rb tree support functions
1812 */
1813static void cfq_del_rq_rb(struct request *rq)
1814{
1815 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1816 const int sync = rq_is_sync(rq);
1817
1818 BUG_ON(!cfqq->queued[sync]);
1819 cfqq->queued[sync]--;
1820
1821 elv_rb_del(&cfqq->sort_list, rq);
1822
1823 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1824 /*
1825 * Queue will be deleted from service tree when we actually
1826 * expire it later. Right now just remove it from prio tree
1827 * as it is empty.
1828 */
1829 if (cfqq->p_root) {
1830 rb_erase(&cfqq->p_node, cfqq->p_root);
1831 cfqq->p_root = NULL;
1832 }
1833 }
1834}
1835
1836static void cfq_add_rq_rb(struct request *rq)
1837{
1838 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1839 struct cfq_data *cfqd = cfqq->cfqd;
1840 struct request *prev;
1841
1842 cfqq->queued[rq_is_sync(rq)]++;
1843
1844 elv_rb_add(&cfqq->sort_list, rq);
1845
1846 if (!cfq_cfqq_on_rr(cfqq))
1847 cfq_add_cfqq_rr(cfqd, cfqq);
1848
1849 /*
1850 * check if this request is a better next-serve candidate
1851 */
1852 prev = cfqq->next_rq;
1853 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1854
1855 /*
1856 * adjust priority tree position, if ->next_rq changes
1857 */
1858 if (prev != cfqq->next_rq)
1859 cfq_prio_tree_add(cfqd, cfqq);
1860
1861 BUG_ON(!cfqq->next_rq);
1862}
1863
1864static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1865{
1866 elv_rb_del(&cfqq->sort_list, rq);
1867 cfqq->queued[rq_is_sync(rq)]--;
1868 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1869 cfq_add_rq_rb(rq);
1870 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
1871 rq->cmd_flags);
1872}
1873
1874static struct request *
1875cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1876{
1877 struct task_struct *tsk = current;
1878 struct cfq_io_cq *cic;
1879 struct cfq_queue *cfqq;
1880
1881 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1882 if (!cic)
1883 return NULL;
1884
1885 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1886 if (cfqq) {
1887 sector_t sector = bio->bi_sector + bio_sectors(bio);
1888
1889 return elv_rb_find(&cfqq->sort_list, sector);
1890 }
1891
1892 return NULL;
1893}
1894
1895static void cfq_activate_request(struct request_queue *q, struct request *rq)
1896{
1897 struct cfq_data *cfqd = q->elevator->elevator_data;
1898
1899 cfqd->rq_in_driver++;
1900 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1901 cfqd->rq_in_driver);
1902
1903 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1904}
1905
1906static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1907{
1908 struct cfq_data *cfqd = q->elevator->elevator_data;
1909
1910 WARN_ON(!cfqd->rq_in_driver);
1911 cfqd->rq_in_driver--;
1912 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1913 cfqd->rq_in_driver);
1914}
1915
1916static void cfq_remove_request(struct request *rq)
1917{
1918 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1919
1920 if (cfqq->next_rq == rq)
1921 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1922
1923 list_del_init(&rq->queuelist);
1924 cfq_del_rq_rb(rq);
1925
1926 cfqq->cfqd->rq_queued--;
1927 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1928 if (rq->cmd_flags & REQ_PRIO) {
1929 WARN_ON(!cfqq->prio_pending);
1930 cfqq->prio_pending--;
1931 }
1932}
1933
1934static int cfq_merge(struct request_queue *q, struct request **req,
1935 struct bio *bio)
1936{
1937 struct cfq_data *cfqd = q->elevator->elevator_data;
1938 struct request *__rq;
1939
1940 __rq = cfq_find_rq_fmerge(cfqd, bio);
1941 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1942 *req = __rq;
1943 return ELEVATOR_FRONT_MERGE;
1944 }
1945
1946 return ELEVATOR_NO_MERGE;
1947}
1948
1949static void cfq_merged_request(struct request_queue *q, struct request *req,
1950 int type)
1951{
1952 if (type == ELEVATOR_FRONT_MERGE) {
1953 struct cfq_queue *cfqq = RQ_CFQQ(req);
1954
1955 cfq_reposition_rq_rb(cfqq, req);
1956 }
1957}
1958
1959static void cfq_bio_merged(struct request_queue *q, struct request *req,
1960 struct bio *bio)
1961{
1962 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
1963}
1964
1965static void
1966cfq_merged_requests(struct request_queue *q, struct request *rq,
1967 struct request *next)
1968{
1969 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1970 struct cfq_data *cfqd = q->elevator->elevator_data;
1971
1972 /*
1973 * reposition in fifo if next is older than rq
1974 */
1975 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1976 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1977 list_move(&rq->queuelist, &next->queuelist);
1978 rq_set_fifo_time(rq, rq_fifo_time(next));
1979 }
1980
1981 if (cfqq->next_rq == next)
1982 cfqq->next_rq = rq;
1983 cfq_remove_request(next);
1984 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
1985
1986 cfqq = RQ_CFQQ(next);
1987 /*
1988 * all requests of this queue are merged to other queues, delete it
1989 * from the service tree. If it's the active_queue,
1990 * cfq_dispatch_requests() will choose to expire it or do idle
1991 */
1992 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
1993 cfqq != cfqd->active_queue)
1994 cfq_del_cfqq_rr(cfqd, cfqq);
1995}
1996
1997static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1998 struct bio *bio)
1999{
2000 struct cfq_data *cfqd = q->elevator->elevator_data;
2001 struct cfq_io_cq *cic;
2002 struct cfq_queue *cfqq;
2003
2004 /*
2005 * Disallow merge of a sync bio into an async request.
2006 */
2007 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
2008 return false;
2009
2010 /*
2011 * Lookup the cfqq that this bio will be queued with and allow
2012 * merge only if rq is queued there.
2013 */
2014 cic = cfq_cic_lookup(cfqd, current->io_context);
2015 if (!cic)
2016 return false;
2017
2018 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2019 return cfqq == RQ_CFQQ(rq);
2020}
2021
2022static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2023{
2024 del_timer(&cfqd->idle_slice_timer);
2025 cfqg_stats_update_idle_time(cfqq->cfqg);
2026}
2027
2028static void __cfq_set_active_queue(struct cfq_data *cfqd,
2029 struct cfq_queue *cfqq)
2030{
2031 if (cfqq) {
2032 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
2033 cfqd->serving_prio, cfqd->serving_type);
2034 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2035 cfqq->slice_start = 0;
2036 cfqq->dispatch_start = jiffies;
2037 cfqq->allocated_slice = 0;
2038 cfqq->slice_end = 0;
2039 cfqq->slice_dispatch = 0;
2040 cfqq->nr_sectors = 0;
2041
2042 cfq_clear_cfqq_wait_request(cfqq);
2043 cfq_clear_cfqq_must_dispatch(cfqq);
2044 cfq_clear_cfqq_must_alloc_slice(cfqq);
2045 cfq_clear_cfqq_fifo_expire(cfqq);
2046 cfq_mark_cfqq_slice_new(cfqq);
2047
2048 cfq_del_timer(cfqd, cfqq);
2049 }
2050
2051 cfqd->active_queue = cfqq;
2052}
2053
2054/*
2055 * current cfqq expired its slice (or was too idle), select new one
2056 */
2057static void
2058__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2059 bool timed_out)
2060{
2061 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2062
2063 if (cfq_cfqq_wait_request(cfqq))
2064 cfq_del_timer(cfqd, cfqq);
2065
2066 cfq_clear_cfqq_wait_request(cfqq);
2067 cfq_clear_cfqq_wait_busy(cfqq);
2068
2069 /*
2070 * If this cfqq is shared between multiple processes, check to
2071 * make sure that those processes are still issuing I/Os within
2072 * the mean seek distance. If not, it may be time to break the
2073 * queues apart again.
2074 */
2075 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2076 cfq_mark_cfqq_split_coop(cfqq);
2077
2078 /*
2079 * store what was left of this slice, if the queue idled/timed out
2080 */
2081 if (timed_out) {
2082 if (cfq_cfqq_slice_new(cfqq))
2083 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2084 else
2085 cfqq->slice_resid = cfqq->slice_end - jiffies;
2086 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
2087 }
2088
2089 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2090
2091 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2092 cfq_del_cfqq_rr(cfqd, cfqq);
2093
2094 cfq_resort_rr_list(cfqd, cfqq);
2095
2096 if (cfqq == cfqd->active_queue)
2097 cfqd->active_queue = NULL;
2098
2099 if (cfqd->active_cic) {
2100 put_io_context(cfqd->active_cic->icq.ioc);
2101 cfqd->active_cic = NULL;
2102 }
2103}
2104
2105static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2106{
2107 struct cfq_queue *cfqq = cfqd->active_queue;
2108
2109 if (cfqq)
2110 __cfq_slice_expired(cfqd, cfqq, timed_out);
2111}
2112
2113/*
2114 * Get next queue for service. Unless we have a queue preemption,
2115 * we'll simply select the first cfqq in the service tree.
2116 */
2117static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2118{
2119 struct cfq_rb_root *service_tree =
2120 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
2121 cfqd->serving_type);
2122
2123 if (!cfqd->rq_queued)
2124 return NULL;
2125
2126 /* There is nothing to dispatch */
2127 if (!service_tree)
2128 return NULL;
2129 if (RB_EMPTY_ROOT(&service_tree->rb))
2130 return NULL;
2131 return cfq_rb_first(service_tree);
2132}
2133
2134static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2135{
2136 struct cfq_group *cfqg;
2137 struct cfq_queue *cfqq;
2138 int i, j;
2139 struct cfq_rb_root *st;
2140
2141 if (!cfqd->rq_queued)
2142 return NULL;
2143
2144 cfqg = cfq_get_next_cfqg(cfqd);
2145 if (!cfqg)
2146 return NULL;
2147
2148 for_each_cfqg_st(cfqg, i, j, st)
2149 if ((cfqq = cfq_rb_first(st)) != NULL)
2150 return cfqq;
2151 return NULL;
2152}
2153
2154/*
2155 * Get and set a new active queue for service.
2156 */
2157static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2158 struct cfq_queue *cfqq)
2159{
2160 if (!cfqq)
2161 cfqq = cfq_get_next_queue(cfqd);
2162
2163 __cfq_set_active_queue(cfqd, cfqq);
2164 return cfqq;
2165}
2166
2167static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2168 struct request *rq)
2169{
2170 if (blk_rq_pos(rq) >= cfqd->last_position)
2171 return blk_rq_pos(rq) - cfqd->last_position;
2172 else
2173 return cfqd->last_position - blk_rq_pos(rq);
2174}
2175
2176static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2177 struct request *rq)
2178{
2179 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2180}
2181
2182static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2183 struct cfq_queue *cur_cfqq)
2184{
2185 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2186 struct rb_node *parent, *node;
2187 struct cfq_queue *__cfqq;
2188 sector_t sector = cfqd->last_position;
2189
2190 if (RB_EMPTY_ROOT(root))
2191 return NULL;
2192
2193 /*
2194 * First, if we find a request starting at the end of the last
2195 * request, choose it.
2196 */
2197 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2198 if (__cfqq)
2199 return __cfqq;
2200
2201 /*
2202 * If the exact sector wasn't found, the parent of the NULL leaf
2203 * will contain the closest sector.
2204 */
2205 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2206 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2207 return __cfqq;
2208
2209 if (blk_rq_pos(__cfqq->next_rq) < sector)
2210 node = rb_next(&__cfqq->p_node);
2211 else
2212 node = rb_prev(&__cfqq->p_node);
2213 if (!node)
2214 return NULL;
2215
2216 __cfqq = rb_entry(node, struct cfq_queue, p_node);
2217 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2218 return __cfqq;
2219
2220 return NULL;
2221}
2222
2223/*
2224 * cfqd - obvious
2225 * cur_cfqq - passed in so that we don't decide that the current queue is
2226 * closely cooperating with itself.
2227 *
2228 * So, basically we're assuming that that cur_cfqq has dispatched at least
2229 * one request, and that cfqd->last_position reflects a position on the disk
2230 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2231 * assumption.
2232 */
2233static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2234 struct cfq_queue *cur_cfqq)
2235{
2236 struct cfq_queue *cfqq;
2237
2238 if (cfq_class_idle(cur_cfqq))
2239 return NULL;
2240 if (!cfq_cfqq_sync(cur_cfqq))
2241 return NULL;
2242 if (CFQQ_SEEKY(cur_cfqq))
2243 return NULL;
2244
2245 /*
2246 * Don't search priority tree if it's the only queue in the group.
2247 */
2248 if (cur_cfqq->cfqg->nr_cfqq == 1)
2249 return NULL;
2250
2251 /*
2252 * We should notice if some of the queues are cooperating, eg
2253 * working closely on the same area of the disk. In that case,
2254 * we can group them together and don't waste time idling.
2255 */
2256 cfqq = cfqq_close(cfqd, cur_cfqq);
2257 if (!cfqq)
2258 return NULL;
2259
2260 /* If new queue belongs to different cfq_group, don't choose it */
2261 if (cur_cfqq->cfqg != cfqq->cfqg)
2262 return NULL;
2263
2264 /*
2265 * It only makes sense to merge sync queues.
2266 */
2267 if (!cfq_cfqq_sync(cfqq))
2268 return NULL;
2269 if (CFQQ_SEEKY(cfqq))
2270 return NULL;
2271
2272 /*
2273 * Do not merge queues of different priority classes
2274 */
2275 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2276 return NULL;
2277
2278 return cfqq;
2279}
2280
2281/*
2282 * Determine whether we should enforce idle window for this queue.
2283 */
2284
2285static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2286{
2287 enum wl_prio_t prio = cfqq_prio(cfqq);
2288 struct cfq_rb_root *service_tree = cfqq->service_tree;
2289
2290 BUG_ON(!service_tree);
2291 BUG_ON(!service_tree->count);
2292
2293 if (!cfqd->cfq_slice_idle)
2294 return false;
2295
2296 /* We never do for idle class queues. */
2297 if (prio == IDLE_WORKLOAD)
2298 return false;
2299
2300 /* We do for queues that were marked with idle window flag. */
2301 if (cfq_cfqq_idle_window(cfqq) &&
2302 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2303 return true;
2304
2305 /*
2306 * Otherwise, we do only if they are the last ones
2307 * in their service tree.
2308 */
2309 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
2310 !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
2311 return true;
2312 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
2313 service_tree->count);
2314 return false;
2315}
2316
2317static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2318{
2319 struct cfq_queue *cfqq = cfqd->active_queue;
2320 struct cfq_io_cq *cic;
2321 unsigned long sl, group_idle = 0;
2322
2323 /*
2324 * SSD device without seek penalty, disable idling. But only do so
2325 * for devices that support queuing, otherwise we still have a problem
2326 * with sync vs async workloads.
2327 */
2328 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2329 return;
2330
2331 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2332 WARN_ON(cfq_cfqq_slice_new(cfqq));
2333
2334 /*
2335 * idle is disabled, either manually or by past process history
2336 */
2337 if (!cfq_should_idle(cfqd, cfqq)) {
2338 /* no queue idling. Check for group idling */
2339 if (cfqd->cfq_group_idle)
2340 group_idle = cfqd->cfq_group_idle;
2341 else
2342 return;
2343 }
2344
2345 /*
2346 * still active requests from this queue, don't idle
2347 */
2348 if (cfqq->dispatched)
2349 return;
2350
2351 /*
2352 * task has exited, don't wait
2353 */
2354 cic = cfqd->active_cic;
2355 if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2356 return;
2357
2358 /*
2359 * If our average think time is larger than the remaining time
2360 * slice, then don't idle. This avoids overrunning the allotted
2361 * time slice.
2362 */
2363 if (sample_valid(cic->ttime.ttime_samples) &&
2364 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2365 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2366 cic->ttime.ttime_mean);
2367 return;
2368 }
2369
2370 /* There are other queues in the group, don't do group idle */
2371 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2372 return;
2373
2374 cfq_mark_cfqq_wait_request(cfqq);
2375
2376 if (group_idle)
2377 sl = cfqd->cfq_group_idle;
2378 else
2379 sl = cfqd->cfq_slice_idle;
2380
2381 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2382 cfqg_stats_set_start_idle_time(cfqq->cfqg);
2383 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2384 group_idle ? 1 : 0);
2385}
2386
2387/*
2388 * Move request from internal lists to the request queue dispatch list.
2389 */
2390static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2391{
2392 struct cfq_data *cfqd = q->elevator->elevator_data;
2393 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2394
2395 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2396
2397 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2398 cfq_remove_request(rq);
2399 cfqq->dispatched++;
2400 (RQ_CFQG(rq))->dispatched++;
2401 elv_dispatch_sort(q, rq);
2402
2403 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2404 cfqq->nr_sectors += blk_rq_sectors(rq);
2405 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
2406}
2407
2408/*
2409 * return expired entry, or NULL to just start from scratch in rbtree
2410 */
2411static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2412{
2413 struct request *rq = NULL;
2414
2415 if (cfq_cfqq_fifo_expire(cfqq))
2416 return NULL;
2417
2418 cfq_mark_cfqq_fifo_expire(cfqq);
2419
2420 if (list_empty(&cfqq->fifo))
2421 return NULL;
2422
2423 rq = rq_entry_fifo(cfqq->fifo.next);
2424 if (time_before(jiffies, rq_fifo_time(rq)))
2425 rq = NULL;
2426
2427 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2428 return rq;
2429}
2430
2431static inline int
2432cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2433{
2434 const int base_rq = cfqd->cfq_slice_async_rq;
2435
2436 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2437
2438 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2439}
2440
2441/*
2442 * Must be called with the queue_lock held.
2443 */
2444static int cfqq_process_refs(struct cfq_queue *cfqq)
2445{
2446 int process_refs, io_refs;
2447
2448 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2449 process_refs = cfqq->ref - io_refs;
2450 BUG_ON(process_refs < 0);
2451 return process_refs;
2452}
2453
2454static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2455{
2456 int process_refs, new_process_refs;
2457 struct cfq_queue *__cfqq;
2458
2459 /*
2460 * If there are no process references on the new_cfqq, then it is
2461 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2462 * chain may have dropped their last reference (not just their
2463 * last process reference).
2464 */
2465 if (!cfqq_process_refs(new_cfqq))
2466 return;
2467
2468 /* Avoid a circular list and skip interim queue merges */
2469 while ((__cfqq = new_cfqq->new_cfqq)) {
2470 if (__cfqq == cfqq)
2471 return;
2472 new_cfqq = __cfqq;
2473 }
2474
2475 process_refs = cfqq_process_refs(cfqq);
2476 new_process_refs = cfqq_process_refs(new_cfqq);
2477 /*
2478 * If the process for the cfqq has gone away, there is no
2479 * sense in merging the queues.
2480 */
2481 if (process_refs == 0 || new_process_refs == 0)
2482 return;
2483
2484 /*
2485 * Merge in the direction of the lesser amount of work.
2486 */
2487 if (new_process_refs >= process_refs) {
2488 cfqq->new_cfqq = new_cfqq;
2489 new_cfqq->ref += process_refs;
2490 } else {
2491 new_cfqq->new_cfqq = cfqq;
2492 cfqq->ref += new_process_refs;
2493 }
2494}
2495
2496static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2497 struct cfq_group *cfqg, enum wl_prio_t prio)
2498{
2499 struct cfq_queue *queue;
2500 int i;
2501 bool key_valid = false;
2502 unsigned long lowest_key = 0;
2503 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2504
2505 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2506 /* select the one with lowest rb_key */
2507 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2508 if (queue &&
2509 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2510 lowest_key = queue->rb_key;
2511 cur_best = i;
2512 key_valid = true;
2513 }
2514 }
2515
2516 return cur_best;
2517}
2518
2519static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2520{
2521 unsigned slice;
2522 unsigned count;
2523 struct cfq_rb_root *st;
2524 unsigned group_slice;
2525 enum wl_prio_t original_prio = cfqd->serving_prio;
2526
2527 /* Choose next priority. RT > BE > IDLE */
2528 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2529 cfqd->serving_prio = RT_WORKLOAD;
2530 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2531 cfqd->serving_prio = BE_WORKLOAD;
2532 else {
2533 cfqd->serving_prio = IDLE_WORKLOAD;
2534 cfqd->workload_expires = jiffies + 1;
2535 return;
2536 }
2537
2538 if (original_prio != cfqd->serving_prio)
2539 goto new_workload;
2540
2541 /*
2542 * For RT and BE, we have to choose also the type
2543 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2544 * expiration time
2545 */
2546 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2547 count = st->count;
2548
2549 /*
2550 * check workload expiration, and that we still have other queues ready
2551 */
2552 if (count && !time_after(jiffies, cfqd->workload_expires))
2553 return;
2554
2555new_workload:
2556 /* otherwise select new workload type */
2557 cfqd->serving_type =
2558 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2559 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2560 count = st->count;
2561
2562 /*
2563 * the workload slice is computed as a fraction of target latency
2564 * proportional to the number of queues in that workload, over
2565 * all the queues in the same priority class
2566 */
2567 group_slice = cfq_group_slice(cfqd, cfqg);
2568
2569 slice = group_slice * count /
2570 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2571 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2572
2573 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2574 unsigned int tmp;
2575
2576 /*
2577 * Async queues are currently system wide. Just taking
2578 * proportion of queues with-in same group will lead to higher
2579 * async ratio system wide as generally root group is going
2580 * to have higher weight. A more accurate thing would be to
2581 * calculate system wide asnc/sync ratio.
2582 */
2583 tmp = cfqd->cfq_target_latency *
2584 cfqg_busy_async_queues(cfqd, cfqg);
2585 tmp = tmp/cfqd->busy_queues;
2586 slice = min_t(unsigned, slice, tmp);
2587
2588 /* async workload slice is scaled down according to
2589 * the sync/async slice ratio. */
2590 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2591 } else
2592 /* sync workload slice is at least 2 * cfq_slice_idle */
2593 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2594
2595 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2596 cfq_log(cfqd, "workload slice:%d", slice);
2597 cfqd->workload_expires = jiffies + slice;
2598}
2599
2600static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2601{
2602 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2603 struct cfq_group *cfqg;
2604
2605 if (RB_EMPTY_ROOT(&st->rb))
2606 return NULL;
2607 cfqg = cfq_rb_first_group(st);
2608 update_min_vdisktime(st);
2609 return cfqg;
2610}
2611
2612static void cfq_choose_cfqg(struct cfq_data *cfqd)
2613{
2614 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2615
2616 cfqd->serving_group = cfqg;
2617
2618 /* Restore the workload type data */
2619 if (cfqg->saved_workload_slice) {
2620 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2621 cfqd->serving_type = cfqg->saved_workload;
2622 cfqd->serving_prio = cfqg->saved_serving_prio;
2623 } else
2624 cfqd->workload_expires = jiffies - 1;
2625
2626 choose_service_tree(cfqd, cfqg);
2627}
2628
2629/*
2630 * Select a queue for service. If we have a current active queue,
2631 * check whether to continue servicing it, or retrieve and set a new one.
2632 */
2633static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2634{
2635 struct cfq_queue *cfqq, *new_cfqq = NULL;
2636
2637 cfqq = cfqd->active_queue;
2638 if (!cfqq)
2639 goto new_queue;
2640
2641 if (!cfqd->rq_queued)
2642 return NULL;
2643
2644 /*
2645 * We were waiting for group to get backlogged. Expire the queue
2646 */
2647 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2648 goto expire;
2649
2650 /*
2651 * The active queue has run out of time, expire it and select new.
2652 */
2653 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2654 /*
2655 * If slice had not expired at the completion of last request
2656 * we might not have turned on wait_busy flag. Don't expire
2657 * the queue yet. Allow the group to get backlogged.
2658 *
2659 * The very fact that we have used the slice, that means we
2660 * have been idling all along on this queue and it should be
2661 * ok to wait for this request to complete.
2662 */
2663 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2664 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2665 cfqq = NULL;
2666 goto keep_queue;
2667 } else
2668 goto check_group_idle;
2669 }
2670
2671 /*
2672 * The active queue has requests and isn't expired, allow it to
2673 * dispatch.
2674 */
2675 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2676 goto keep_queue;
2677
2678 /*
2679 * If another queue has a request waiting within our mean seek
2680 * distance, let it run. The expire code will check for close
2681 * cooperators and put the close queue at the front of the service
2682 * tree. If possible, merge the expiring queue with the new cfqq.
2683 */
2684 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2685 if (new_cfqq) {
2686 if (!cfqq->new_cfqq)
2687 cfq_setup_merge(cfqq, new_cfqq);
2688 goto expire;
2689 }
2690
2691 /*
2692 * No requests pending. If the active queue still has requests in
2693 * flight or is idling for a new request, allow either of these
2694 * conditions to happen (or time out) before selecting a new queue.
2695 */
2696 if (timer_pending(&cfqd->idle_slice_timer)) {
2697 cfqq = NULL;
2698 goto keep_queue;
2699 }
2700
2701 /*
2702 * This is a deep seek queue, but the device is much faster than
2703 * the queue can deliver, don't idle
2704 **/
2705 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2706 (cfq_cfqq_slice_new(cfqq) ||
2707 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2708 cfq_clear_cfqq_deep(cfqq);
2709 cfq_clear_cfqq_idle_window(cfqq);
2710 }
2711
2712 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2713 cfqq = NULL;
2714 goto keep_queue;
2715 }
2716
2717 /*
2718 * If group idle is enabled and there are requests dispatched from
2719 * this group, wait for requests to complete.
2720 */
2721check_group_idle:
2722 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
2723 cfqq->cfqg->dispatched &&
2724 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
2725 cfqq = NULL;
2726 goto keep_queue;
2727 }
2728
2729expire:
2730 cfq_slice_expired(cfqd, 0);
2731new_queue:
2732 /*
2733 * Current queue expired. Check if we have to switch to a new
2734 * service tree
2735 */
2736 if (!new_cfqq)
2737 cfq_choose_cfqg(cfqd);
2738
2739 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2740keep_queue:
2741 return cfqq;
2742}
2743
2744static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2745{
2746 int dispatched = 0;
2747
2748 while (cfqq->next_rq) {
2749 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2750 dispatched++;
2751 }
2752
2753 BUG_ON(!list_empty(&cfqq->fifo));
2754
2755 /* By default cfqq is not expired if it is empty. Do it explicitly */
2756 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2757 return dispatched;
2758}
2759
2760/*
2761 * Drain our current requests. Used for barriers and when switching
2762 * io schedulers on-the-fly.
2763 */
2764static int cfq_forced_dispatch(struct cfq_data *cfqd)
2765{
2766 struct cfq_queue *cfqq;
2767 int dispatched = 0;
2768
2769 /* Expire the timeslice of the current active queue first */
2770 cfq_slice_expired(cfqd, 0);
2771 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2772 __cfq_set_active_queue(cfqd, cfqq);
2773 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2774 }
2775
2776 BUG_ON(cfqd->busy_queues);
2777
2778 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2779 return dispatched;
2780}
2781
2782static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2783 struct cfq_queue *cfqq)
2784{
2785 /* the queue hasn't finished any request, can't estimate */
2786 if (cfq_cfqq_slice_new(cfqq))
2787 return true;
2788 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2789 cfqq->slice_end))
2790 return true;
2791
2792 return false;
2793}
2794
2795static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2796{
2797 unsigned int max_dispatch;
2798
2799 /*
2800 * Drain async requests before we start sync IO
2801 */
2802 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2803 return false;
2804
2805 /*
2806 * If this is an async queue and we have sync IO in flight, let it wait
2807 */
2808 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2809 return false;
2810
2811 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2812 if (cfq_class_idle(cfqq))
2813 max_dispatch = 1;
2814
2815 /*
2816 * Does this cfqq already have too much IO in flight?
2817 */
2818 if (cfqq->dispatched >= max_dispatch) {
2819 bool promote_sync = false;
2820 /*
2821 * idle queue must always only have a single IO in flight
2822 */
2823 if (cfq_class_idle(cfqq))
2824 return false;
2825
2826 /*
2827 * If there is only one sync queue
2828 * we can ignore async queue here and give the sync
2829 * queue no dispatch limit. The reason is a sync queue can
2830 * preempt async queue, limiting the sync queue doesn't make
2831 * sense. This is useful for aiostress test.
2832 */
2833 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2834 promote_sync = true;
2835
2836 /*
2837 * We have other queues, don't allow more IO from this one
2838 */
2839 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2840 !promote_sync)
2841 return false;
2842
2843 /*
2844 * Sole queue user, no limit
2845 */
2846 if (cfqd->busy_queues == 1 || promote_sync)
2847 max_dispatch = -1;
2848 else
2849 /*
2850 * Normally we start throttling cfqq when cfq_quantum/2
2851 * requests have been dispatched. But we can drive
2852 * deeper queue depths at the beginning of slice
2853 * subjected to upper limit of cfq_quantum.
2854 * */
2855 max_dispatch = cfqd->cfq_quantum;
2856 }
2857
2858 /*
2859 * Async queues must wait a bit before being allowed dispatch.
2860 * We also ramp up the dispatch depth gradually for async IO,
2861 * based on the last sync IO we serviced
2862 */
2863 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2864 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2865 unsigned int depth;
2866
2867 depth = last_sync / cfqd->cfq_slice[1];
2868 if (!depth && !cfqq->dispatched)
2869 depth = 1;
2870 if (depth < max_dispatch)
2871 max_dispatch = depth;
2872 }
2873
2874 /*
2875 * If we're below the current max, allow a dispatch
2876 */
2877 return cfqq->dispatched < max_dispatch;
2878}
2879
2880/*
2881 * Dispatch a request from cfqq, moving them to the request queue
2882 * dispatch list.
2883 */
2884static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2885{
2886 struct request *rq;
2887
2888 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2889
2890 if (!cfq_may_dispatch(cfqd, cfqq))
2891 return false;
2892
2893 /*
2894 * follow expired path, else get first next available
2895 */
2896 rq = cfq_check_fifo(cfqq);
2897 if (!rq)
2898 rq = cfqq->next_rq;
2899
2900 /*
2901 * insert request into driver dispatch list
2902 */
2903 cfq_dispatch_insert(cfqd->queue, rq);
2904
2905 if (!cfqd->active_cic) {
2906 struct cfq_io_cq *cic = RQ_CIC(rq);
2907
2908 atomic_long_inc(&cic->icq.ioc->refcount);
2909 cfqd->active_cic = cic;
2910 }
2911
2912 return true;
2913}
2914
2915/*
2916 * Find the cfqq that we need to service and move a request from that to the
2917 * dispatch list
2918 */
2919static int cfq_dispatch_requests(struct request_queue *q, int force)
2920{
2921 struct cfq_data *cfqd = q->elevator->elevator_data;
2922 struct cfq_queue *cfqq;
2923
2924 if (!cfqd->busy_queues)
2925 return 0;
2926
2927 if (unlikely(force))
2928 return cfq_forced_dispatch(cfqd);
2929
2930 cfqq = cfq_select_queue(cfqd);
2931 if (!cfqq)
2932 return 0;
2933
2934 /*
2935 * Dispatch a request from this cfqq, if it is allowed
2936 */
2937 if (!cfq_dispatch_request(cfqd, cfqq))
2938 return 0;
2939
2940 cfqq->slice_dispatch++;
2941 cfq_clear_cfqq_must_dispatch(cfqq);
2942
2943 /*
2944 * expire an async queue immediately if it has used up its slice. idle
2945 * queue always expire after 1 dispatch round.
2946 */
2947 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2948 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2949 cfq_class_idle(cfqq))) {
2950 cfqq->slice_end = jiffies + 1;
2951 cfq_slice_expired(cfqd, 0);
2952 }
2953
2954 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2955 return 1;
2956}
2957
2958/*
2959 * task holds one reference to the queue, dropped when task exits. each rq
2960 * in-flight on this queue also holds a reference, dropped when rq is freed.
2961 *
2962 * Each cfq queue took a reference on the parent group. Drop it now.
2963 * queue lock must be held here.
2964 */
2965static void cfq_put_queue(struct cfq_queue *cfqq)
2966{
2967 struct cfq_data *cfqd = cfqq->cfqd;
2968 struct cfq_group *cfqg;
2969
2970 BUG_ON(cfqq->ref <= 0);
2971
2972 cfqq->ref--;
2973 if (cfqq->ref)
2974 return;
2975
2976 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2977 BUG_ON(rb_first(&cfqq->sort_list));
2978 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2979 cfqg = cfqq->cfqg;
2980
2981 if (unlikely(cfqd->active_queue == cfqq)) {
2982 __cfq_slice_expired(cfqd, cfqq, 0);
2983 cfq_schedule_dispatch(cfqd);
2984 }
2985
2986 BUG_ON(cfq_cfqq_on_rr(cfqq));
2987 kmem_cache_free(cfq_pool, cfqq);
2988 cfqg_put(cfqg);
2989}
2990
2991static void cfq_put_cooperator(struct cfq_queue *cfqq)
2992{
2993 struct cfq_queue *__cfqq, *next;
2994
2995 /*
2996 * If this queue was scheduled to merge with another queue, be
2997 * sure to drop the reference taken on that queue (and others in
2998 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2999 */
3000 __cfqq = cfqq->new_cfqq;
3001 while (__cfqq) {
3002 if (__cfqq == cfqq) {
3003 WARN(1, "cfqq->new_cfqq loop detected\n");
3004 break;
3005 }
3006 next = __cfqq->new_cfqq;
3007 cfq_put_queue(__cfqq);
3008 __cfqq = next;
3009 }
3010}
3011
3012static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3013{
3014 if (unlikely(cfqq == cfqd->active_queue)) {
3015 __cfq_slice_expired(cfqd, cfqq, 0);
3016 cfq_schedule_dispatch(cfqd);
3017 }
3018
3019 cfq_put_cooperator(cfqq);
3020
3021 cfq_put_queue(cfqq);
3022}
3023
3024static void cfq_init_icq(struct io_cq *icq)
3025{
3026 struct cfq_io_cq *cic = icq_to_cic(icq);
3027
3028 cic->ttime.last_end_request = jiffies;
3029}
3030
3031static void cfq_exit_icq(struct io_cq *icq)
3032{
3033 struct cfq_io_cq *cic = icq_to_cic(icq);
3034 struct cfq_data *cfqd = cic_to_cfqd(cic);
3035
3036 if (cic->cfqq[BLK_RW_ASYNC]) {
3037 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
3038 cic->cfqq[BLK_RW_ASYNC] = NULL;
3039 }
3040
3041 if (cic->cfqq[BLK_RW_SYNC]) {
3042 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
3043 cic->cfqq[BLK_RW_SYNC] = NULL;
3044 }
3045}
3046
3047static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3048{
3049 struct task_struct *tsk = current;
3050 int ioprio_class;
3051
3052 if (!cfq_cfqq_prio_changed(cfqq))
3053 return;
3054
3055 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3056 switch (ioprio_class) {
3057 default:
3058 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3059 case IOPRIO_CLASS_NONE:
3060 /*
3061 * no prio set, inherit CPU scheduling settings
3062 */
3063 cfqq->ioprio = task_nice_ioprio(tsk);
3064 cfqq->ioprio_class = task_nice_ioclass(tsk);
3065 break;
3066 case IOPRIO_CLASS_RT:
3067 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3068 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3069 break;
3070 case IOPRIO_CLASS_BE:
3071 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3072 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3073 break;
3074 case IOPRIO_CLASS_IDLE:
3075 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3076 cfqq->ioprio = 7;
3077 cfq_clear_cfqq_idle_window(cfqq);
3078 break;
3079 }
3080
3081 /*
3082 * keep track of original prio settings in case we have to temporarily
3083 * elevate the priority of this queue
3084 */
3085 cfqq->org_ioprio = cfqq->ioprio;
3086 cfq_clear_cfqq_prio_changed(cfqq);
3087}
3088
3089static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3090{
3091 int ioprio = cic->icq.ioc->ioprio;
3092 struct cfq_data *cfqd = cic_to_cfqd(cic);
3093 struct cfq_queue *cfqq;
3094
3095 /*
3096 * Check whether ioprio has changed. The condition may trigger
3097 * spuriously on a newly created cic but there's no harm.
3098 */
3099 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3100 return;
3101
3102 cfqq = cic->cfqq[BLK_RW_ASYNC];
3103 if (cfqq) {
3104 struct cfq_queue *new_cfqq;
3105 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio,
3106 GFP_ATOMIC);
3107 if (new_cfqq) {
3108 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
3109 cfq_put_queue(cfqq);
3110 }
3111 }
3112
3113 cfqq = cic->cfqq[BLK_RW_SYNC];
3114 if (cfqq)
3115 cfq_mark_cfqq_prio_changed(cfqq);
3116
3117 cic->ioprio = ioprio;
3118}
3119
3120static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3121 pid_t pid, bool is_sync)
3122{
3123 RB_CLEAR_NODE(&cfqq->rb_node);
3124 RB_CLEAR_NODE(&cfqq->p_node);
3125 INIT_LIST_HEAD(&cfqq->fifo);
3126
3127 cfqq->ref = 0;
3128 cfqq->cfqd = cfqd;
3129
3130 cfq_mark_cfqq_prio_changed(cfqq);
3131
3132 if (is_sync) {
3133 if (!cfq_class_idle(cfqq))
3134 cfq_mark_cfqq_idle_window(cfqq);
3135 cfq_mark_cfqq_sync(cfqq);
3136 }
3137 cfqq->pid = pid;
3138}
3139
3140#ifdef CONFIG_CFQ_GROUP_IOSCHED
3141static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3142{
3143 struct cfq_data *cfqd = cic_to_cfqd(cic);
3144 struct cfq_queue *sync_cfqq;
3145 uint64_t id;
3146
3147 rcu_read_lock();
3148 id = bio_blkcg(bio)->id;
3149 rcu_read_unlock();
3150
3151 /*
3152 * Check whether blkcg has changed. The condition may trigger
3153 * spuriously on a newly created cic but there's no harm.
3154 */
3155 if (unlikely(!cfqd) || likely(cic->blkcg_id == id))
3156 return;
3157
3158 sync_cfqq = cic_to_cfqq(cic, 1);
3159 if (sync_cfqq) {
3160 /*
3161 * Drop reference to sync queue. A new sync queue will be
3162 * assigned in new group upon arrival of a fresh request.
3163 */
3164 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
3165 cic_set_cfqq(cic, NULL, 1);
3166 cfq_put_queue(sync_cfqq);
3167 }
3168
3169 cic->blkcg_id = id;
3170}
3171#else
3172static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
3173#endif /* CONFIG_CFQ_GROUP_IOSCHED */
3174
3175static struct cfq_queue *
3176cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3177 struct bio *bio, gfp_t gfp_mask)
3178{
3179 struct blkcg *blkcg;
3180 struct cfq_queue *cfqq, *new_cfqq = NULL;
3181 struct cfq_group *cfqg;
3182
3183retry:
3184 rcu_read_lock();
3185
3186 blkcg = bio_blkcg(bio);
3187 cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
3188 cfqq = cic_to_cfqq(cic, is_sync);
3189
3190 /*
3191 * Always try a new alloc if we fell back to the OOM cfqq
3192 * originally, since it should just be a temporary situation.
3193 */
3194 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3195 cfqq = NULL;
3196 if (new_cfqq) {
3197 cfqq = new_cfqq;
3198 new_cfqq = NULL;
3199 } else if (gfp_mask & __GFP_WAIT) {
3200 rcu_read_unlock();
3201 spin_unlock_irq(cfqd->queue->queue_lock);
3202 new_cfqq = kmem_cache_alloc_node(cfq_pool,
3203 gfp_mask | __GFP_ZERO,
3204 cfqd->queue->node);
3205 spin_lock_irq(cfqd->queue->queue_lock);
3206 if (new_cfqq)
3207 goto retry;
3208 } else {
3209 cfqq = kmem_cache_alloc_node(cfq_pool,
3210 gfp_mask | __GFP_ZERO,
3211 cfqd->queue->node);
3212 }
3213
3214 if (cfqq) {
3215 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3216 cfq_init_prio_data(cfqq, cic);
3217 cfq_link_cfqq_cfqg(cfqq, cfqg);
3218 cfq_log_cfqq(cfqd, cfqq, "alloced");
3219 } else
3220 cfqq = &cfqd->oom_cfqq;
3221 }
3222
3223 if (new_cfqq)
3224 kmem_cache_free(cfq_pool, new_cfqq);
3225
3226 rcu_read_unlock();
3227 return cfqq;
3228}
3229
3230static struct cfq_queue **
3231cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3232{
3233 switch (ioprio_class) {
3234 case IOPRIO_CLASS_RT:
3235 return &cfqd->async_cfqq[0][ioprio];
3236 case IOPRIO_CLASS_NONE:
3237 ioprio = IOPRIO_NORM;
3238 /* fall through */
3239 case IOPRIO_CLASS_BE:
3240 return &cfqd->async_cfqq[1][ioprio];
3241 case IOPRIO_CLASS_IDLE:
3242 return &cfqd->async_idle_cfqq;
3243 default:
3244 BUG();
3245 }
3246}
3247
3248static struct cfq_queue *
3249cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3250 struct bio *bio, gfp_t gfp_mask)
3251{
3252 const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3253 const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3254 struct cfq_queue **async_cfqq = NULL;
3255 struct cfq_queue *cfqq = NULL;
3256
3257 if (!is_sync) {
3258 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3259 cfqq = *async_cfqq;
3260 }
3261
3262 if (!cfqq)
3263 cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask);
3264
3265 /*
3266 * pin the queue now that it's allocated, scheduler exit will prune it
3267 */
3268 if (!is_sync && !(*async_cfqq)) {
3269 cfqq->ref++;
3270 *async_cfqq = cfqq;
3271 }
3272
3273 cfqq->ref++;
3274 return cfqq;
3275}
3276
3277static void
3278__cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3279{
3280 unsigned long elapsed = jiffies - ttime->last_end_request;
3281 elapsed = min(elapsed, 2UL * slice_idle);
3282
3283 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3284 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3285 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3286}
3287
3288static void
3289cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3290 struct cfq_io_cq *cic)
3291{
3292 if (cfq_cfqq_sync(cfqq)) {
3293 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3294 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3295 cfqd->cfq_slice_idle);
3296 }
3297#ifdef CONFIG_CFQ_GROUP_IOSCHED
3298 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3299#endif
3300}
3301
3302static void
3303cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3304 struct request *rq)
3305{
3306 sector_t sdist = 0;
3307 sector_t n_sec = blk_rq_sectors(rq);
3308 if (cfqq->last_request_pos) {
3309 if (cfqq->last_request_pos < blk_rq_pos(rq))
3310 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3311 else
3312 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3313 }
3314
3315 cfqq->seek_history <<= 1;
3316 if (blk_queue_nonrot(cfqd->queue))
3317 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3318 else
3319 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3320}
3321
3322/*
3323 * Disable idle window if the process thinks too long or seeks so much that
3324 * it doesn't matter
3325 */
3326static void
3327cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3328 struct cfq_io_cq *cic)
3329{
3330 int old_idle, enable_idle;
3331
3332 /*
3333 * Don't idle for async or idle io prio class
3334 */
3335 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3336 return;
3337
3338 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3339
3340 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3341 cfq_mark_cfqq_deep(cfqq);
3342
3343 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3344 enable_idle = 0;
3345 else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3346 !cfqd->cfq_slice_idle ||
3347 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3348 enable_idle = 0;
3349 else if (sample_valid(cic->ttime.ttime_samples)) {
3350 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3351 enable_idle = 0;
3352 else
3353 enable_idle = 1;
3354 }
3355
3356 if (old_idle != enable_idle) {
3357 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3358 if (enable_idle)
3359 cfq_mark_cfqq_idle_window(cfqq);
3360 else
3361 cfq_clear_cfqq_idle_window(cfqq);
3362 }
3363}
3364
3365/*
3366 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3367 * no or if we aren't sure, a 1 will cause a preempt.
3368 */
3369static bool
3370cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3371 struct request *rq)
3372{
3373 struct cfq_queue *cfqq;
3374
3375 cfqq = cfqd->active_queue;
3376 if (!cfqq)
3377 return false;
3378
3379 if (cfq_class_idle(new_cfqq))
3380 return false;
3381
3382 if (cfq_class_idle(cfqq))
3383 return true;
3384
3385 /*
3386 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3387 */
3388 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3389 return false;
3390
3391 /*
3392 * if the new request is sync, but the currently running queue is
3393 * not, let the sync request have priority.
3394 */
3395 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3396 return true;
3397
3398 if (new_cfqq->cfqg != cfqq->cfqg)
3399 return false;
3400
3401 if (cfq_slice_used(cfqq))
3402 return true;
3403
3404 /* Allow preemption only if we are idling on sync-noidle tree */
3405 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3406 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3407 new_cfqq->service_tree->count == 2 &&
3408 RB_EMPTY_ROOT(&cfqq->sort_list))
3409 return true;
3410
3411 /*
3412 * So both queues are sync. Let the new request get disk time if
3413 * it's a metadata request and the current queue is doing regular IO.
3414 */
3415 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3416 return true;
3417
3418 /*
3419 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3420 */
3421 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3422 return true;
3423
3424 /* An idle queue should not be idle now for some reason */
3425 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3426 return true;
3427
3428 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3429 return false;
3430
3431 /*
3432 * if this request is as-good as one we would expect from the
3433 * current cfqq, let it preempt
3434 */
3435 if (cfq_rq_close(cfqd, cfqq, rq))
3436 return true;
3437
3438 return false;
3439}
3440
3441/*
3442 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3443 * let it have half of its nominal slice.
3444 */
3445static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3446{
3447 enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3448
3449 cfq_log_cfqq(cfqd, cfqq, "preempt");
3450 cfq_slice_expired(cfqd, 1);
3451
3452 /*
3453 * workload type is changed, don't save slice, otherwise preempt
3454 * doesn't happen
3455 */
3456 if (old_type != cfqq_type(cfqq))
3457 cfqq->cfqg->saved_workload_slice = 0;
3458
3459 /*
3460 * Put the new queue at the front of the of the current list,
3461 * so we know that it will be selected next.
3462 */
3463 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3464
3465 cfq_service_tree_add(cfqd, cfqq, 1);
3466
3467 cfqq->slice_end = 0;
3468 cfq_mark_cfqq_slice_new(cfqq);
3469}
3470
3471/*
3472 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3473 * something we should do about it
3474 */
3475static void
3476cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3477 struct request *rq)
3478{
3479 struct cfq_io_cq *cic = RQ_CIC(rq);
3480
3481 cfqd->rq_queued++;
3482 if (rq->cmd_flags & REQ_PRIO)
3483 cfqq->prio_pending++;
3484
3485 cfq_update_io_thinktime(cfqd, cfqq, cic);
3486 cfq_update_io_seektime(cfqd, cfqq, rq);
3487 cfq_update_idle_window(cfqd, cfqq, cic);
3488
3489 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3490
3491 if (cfqq == cfqd->active_queue) {
3492 /*
3493 * Remember that we saw a request from this process, but
3494 * don't start queuing just yet. Otherwise we risk seeing lots
3495 * of tiny requests, because we disrupt the normal plugging
3496 * and merging. If the request is already larger than a single
3497 * page, let it rip immediately. For that case we assume that
3498 * merging is already done. Ditto for a busy system that
3499 * has other work pending, don't risk delaying until the
3500 * idle timer unplug to continue working.
3501 */
3502 if (cfq_cfqq_wait_request(cfqq)) {
3503 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3504 cfqd->busy_queues > 1) {
3505 cfq_del_timer(cfqd, cfqq);
3506 cfq_clear_cfqq_wait_request(cfqq);
3507 __blk_run_queue(cfqd->queue);
3508 } else {
3509 cfqg_stats_update_idle_time(cfqq->cfqg);
3510 cfq_mark_cfqq_must_dispatch(cfqq);
3511 }
3512 }
3513 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3514 /*
3515 * not the active queue - expire current slice if it is
3516 * idle and has expired it's mean thinktime or this new queue
3517 * has some old slice time left and is of higher priority or
3518 * this new queue is RT and the current one is BE
3519 */
3520 cfq_preempt_queue(cfqd, cfqq);
3521 __blk_run_queue(cfqd->queue);
3522 }
3523}
3524
3525static void cfq_insert_request(struct request_queue *q, struct request *rq)
3526{
3527 struct cfq_data *cfqd = q->elevator->elevator_data;
3528 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3529
3530 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3531 cfq_init_prio_data(cfqq, RQ_CIC(rq));
3532
3533 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3534 list_add_tail(&rq->queuelist, &cfqq->fifo);
3535 cfq_add_rq_rb(rq);
3536 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
3537 rq->cmd_flags);
3538 cfq_rq_enqueued(cfqd, cfqq, rq);
3539}
3540
3541/*
3542 * Update hw_tag based on peak queue depth over 50 samples under
3543 * sufficient load.
3544 */
3545static void cfq_update_hw_tag(struct cfq_data *cfqd)
3546{
3547 struct cfq_queue *cfqq = cfqd->active_queue;
3548
3549 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3550 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3551
3552 if (cfqd->hw_tag == 1)
3553 return;
3554
3555 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3556 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3557 return;
3558
3559 /*
3560 * If active queue hasn't enough requests and can idle, cfq might not
3561 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3562 * case
3563 */
3564 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3565 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3566 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3567 return;
3568
3569 if (cfqd->hw_tag_samples++ < 50)
3570 return;
3571
3572 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3573 cfqd->hw_tag = 1;
3574 else
3575 cfqd->hw_tag = 0;
3576}
3577
3578static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3579{
3580 struct cfq_io_cq *cic = cfqd->active_cic;
3581
3582 /* If the queue already has requests, don't wait */
3583 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3584 return false;
3585
3586 /* If there are other queues in the group, don't wait */
3587 if (cfqq->cfqg->nr_cfqq > 1)
3588 return false;
3589
3590 /* the only queue in the group, but think time is big */
3591 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
3592 return false;
3593
3594 if (cfq_slice_used(cfqq))
3595 return true;
3596
3597 /* if slice left is less than think time, wait busy */
3598 if (cic && sample_valid(cic->ttime.ttime_samples)
3599 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
3600 return true;
3601
3602 /*
3603 * If think times is less than a jiffy than ttime_mean=0 and above
3604 * will not be true. It might happen that slice has not expired yet
3605 * but will expire soon (4-5 ns) during select_queue(). To cover the
3606 * case where think time is less than a jiffy, mark the queue wait
3607 * busy if only 1 jiffy is left in the slice.
3608 */
3609 if (cfqq->slice_end - jiffies == 1)
3610 return true;
3611
3612 return false;
3613}
3614
3615static void cfq_completed_request(struct request_queue *q, struct request *rq)
3616{
3617 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3618 struct cfq_data *cfqd = cfqq->cfqd;
3619 const int sync = rq_is_sync(rq);
3620 unsigned long now;
3621
3622 now = jiffies;
3623 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3624 !!(rq->cmd_flags & REQ_NOIDLE));
3625
3626 cfq_update_hw_tag(cfqd);
3627
3628 WARN_ON(!cfqd->rq_in_driver);
3629 WARN_ON(!cfqq->dispatched);
3630 cfqd->rq_in_driver--;
3631 cfqq->dispatched--;
3632 (RQ_CFQG(rq))->dispatched--;
3633 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
3634 rq_io_start_time_ns(rq), rq->cmd_flags);
3635
3636 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3637
3638 if (sync) {
3639 struct cfq_rb_root *service_tree;
3640
3641 RQ_CIC(rq)->ttime.last_end_request = now;
3642
3643 if (cfq_cfqq_on_rr(cfqq))
3644 service_tree = cfqq->service_tree;
3645 else
3646 service_tree = service_tree_for(cfqq->cfqg,
3647 cfqq_prio(cfqq), cfqq_type(cfqq));
3648 service_tree->ttime.last_end_request = now;
3649 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3650 cfqd->last_delayed_sync = now;
3651 }
3652
3653#ifdef CONFIG_CFQ_GROUP_IOSCHED
3654 cfqq->cfqg->ttime.last_end_request = now;
3655#endif
3656
3657 /*
3658 * If this is the active queue, check if it needs to be expired,
3659 * or if we want to idle in case it has no pending requests.
3660 */
3661 if (cfqd->active_queue == cfqq) {
3662 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3663
3664 if (cfq_cfqq_slice_new(cfqq)) {
3665 cfq_set_prio_slice(cfqd, cfqq);
3666 cfq_clear_cfqq_slice_new(cfqq);
3667 }
3668
3669 /*
3670 * Should we wait for next request to come in before we expire
3671 * the queue.
3672 */
3673 if (cfq_should_wait_busy(cfqd, cfqq)) {
3674 unsigned long extend_sl = cfqd->cfq_slice_idle;
3675 if (!cfqd->cfq_slice_idle)
3676 extend_sl = cfqd->cfq_group_idle;
3677 cfqq->slice_end = jiffies + extend_sl;
3678 cfq_mark_cfqq_wait_busy(cfqq);
3679 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3680 }
3681
3682 /*
3683 * Idling is not enabled on:
3684 * - expired queues
3685 * - idle-priority queues
3686 * - async queues
3687 * - queues with still some requests queued
3688 * - when there is a close cooperator
3689 */
3690 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3691 cfq_slice_expired(cfqd, 1);
3692 else if (sync && cfqq_empty &&
3693 !cfq_close_cooperator(cfqd, cfqq)) {
3694 cfq_arm_slice_timer(cfqd);
3695 }
3696 }
3697
3698 if (!cfqd->rq_in_driver)
3699 cfq_schedule_dispatch(cfqd);
3700}
3701
3702static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3703{
3704 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3705 cfq_mark_cfqq_must_alloc_slice(cfqq);
3706 return ELV_MQUEUE_MUST;
3707 }
3708
3709 return ELV_MQUEUE_MAY;
3710}
3711
3712static int cfq_may_queue(struct request_queue *q, int rw)
3713{
3714 struct cfq_data *cfqd = q->elevator->elevator_data;
3715 struct task_struct *tsk = current;
3716 struct cfq_io_cq *cic;
3717 struct cfq_queue *cfqq;
3718
3719 /*
3720 * don't force setup of a queue from here, as a call to may_queue
3721 * does not necessarily imply that a request actually will be queued.
3722 * so just lookup a possibly existing queue, or return 'may queue'
3723 * if that fails
3724 */
3725 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3726 if (!cic)
3727 return ELV_MQUEUE_MAY;
3728
3729 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3730 if (cfqq) {
3731 cfq_init_prio_data(cfqq, cic);
3732
3733 return __cfq_may_queue(cfqq);
3734 }
3735
3736 return ELV_MQUEUE_MAY;
3737}
3738
3739/*
3740 * queue lock held here
3741 */
3742static void cfq_put_request(struct request *rq)
3743{
3744 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3745
3746 if (cfqq) {
3747 const int rw = rq_data_dir(rq);
3748
3749 BUG_ON(!cfqq->allocated[rw]);
3750 cfqq->allocated[rw]--;
3751
3752 /* Put down rq reference on cfqg */
3753 cfqg_put(RQ_CFQG(rq));
3754 rq->elv.priv[0] = NULL;
3755 rq->elv.priv[1] = NULL;
3756
3757 cfq_put_queue(cfqq);
3758 }
3759}
3760
3761static struct cfq_queue *
3762cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
3763 struct cfq_queue *cfqq)
3764{
3765 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3766 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3767 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3768 cfq_put_queue(cfqq);
3769 return cic_to_cfqq(cic, 1);
3770}
3771
3772/*
3773 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3774 * was the last process referring to said cfqq.
3775 */
3776static struct cfq_queue *
3777split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
3778{
3779 if (cfqq_process_refs(cfqq) == 1) {
3780 cfqq->pid = current->pid;
3781 cfq_clear_cfqq_coop(cfqq);
3782 cfq_clear_cfqq_split_coop(cfqq);
3783 return cfqq;
3784 }
3785
3786 cic_set_cfqq(cic, NULL, 1);
3787
3788 cfq_put_cooperator(cfqq);
3789
3790 cfq_put_queue(cfqq);
3791 return NULL;
3792}
3793/*
3794 * Allocate cfq data structures associated with this request.
3795 */
3796static int
3797cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
3798 gfp_t gfp_mask)
3799{
3800 struct cfq_data *cfqd = q->elevator->elevator_data;
3801 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
3802 const int rw = rq_data_dir(rq);
3803 const bool is_sync = rq_is_sync(rq);
3804 struct cfq_queue *cfqq;
3805
3806 might_sleep_if(gfp_mask & __GFP_WAIT);
3807
3808 spin_lock_irq(q->queue_lock);
3809
3810 check_ioprio_changed(cic, bio);
3811 check_blkcg_changed(cic, bio);
3812new_queue:
3813 cfqq = cic_to_cfqq(cic, is_sync);
3814 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3815 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask);
3816 cic_set_cfqq(cic, cfqq, is_sync);
3817 } else {
3818 /*
3819 * If the queue was seeky for too long, break it apart.
3820 */
3821 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3822 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3823 cfqq = split_cfqq(cic, cfqq);
3824 if (!cfqq)
3825 goto new_queue;
3826 }
3827
3828 /*
3829 * Check to see if this queue is scheduled to merge with
3830 * another, closely cooperating queue. The merging of
3831 * queues happens here as it must be done in process context.
3832 * The reference on new_cfqq was taken in merge_cfqqs.
3833 */
3834 if (cfqq->new_cfqq)
3835 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3836 }
3837
3838 cfqq->allocated[rw]++;
3839
3840 cfqq->ref++;
3841 cfqg_get(cfqq->cfqg);
3842 rq->elv.priv[0] = cfqq;
3843 rq->elv.priv[1] = cfqq->cfqg;
3844 spin_unlock_irq(q->queue_lock);
3845 return 0;
3846}
3847
3848static void cfq_kick_queue(struct work_struct *work)
3849{
3850 struct cfq_data *cfqd =
3851 container_of(work, struct cfq_data, unplug_work);
3852 struct request_queue *q = cfqd->queue;
3853
3854 spin_lock_irq(q->queue_lock);
3855 __blk_run_queue(cfqd->queue);
3856 spin_unlock_irq(q->queue_lock);
3857}
3858
3859/*
3860 * Timer running if the active_queue is currently idling inside its time slice
3861 */
3862static void cfq_idle_slice_timer(unsigned long data)
3863{
3864 struct cfq_data *cfqd = (struct cfq_data *) data;
3865 struct cfq_queue *cfqq;
3866 unsigned long flags;
3867 int timed_out = 1;
3868
3869 cfq_log(cfqd, "idle timer fired");
3870
3871 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3872
3873 cfqq = cfqd->active_queue;
3874 if (cfqq) {
3875 timed_out = 0;
3876
3877 /*
3878 * We saw a request before the queue expired, let it through
3879 */
3880 if (cfq_cfqq_must_dispatch(cfqq))
3881 goto out_kick;
3882
3883 /*
3884 * expired
3885 */
3886 if (cfq_slice_used(cfqq))
3887 goto expire;
3888
3889 /*
3890 * only expire and reinvoke request handler, if there are
3891 * other queues with pending requests
3892 */
3893 if (!cfqd->busy_queues)
3894 goto out_cont;
3895
3896 /*
3897 * not expired and it has a request pending, let it dispatch
3898 */
3899 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3900 goto out_kick;
3901
3902 /*
3903 * Queue depth flag is reset only when the idle didn't succeed
3904 */
3905 cfq_clear_cfqq_deep(cfqq);
3906 }
3907expire:
3908 cfq_slice_expired(cfqd, timed_out);
3909out_kick:
3910 cfq_schedule_dispatch(cfqd);
3911out_cont:
3912 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3913}
3914
3915static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3916{
3917 del_timer_sync(&cfqd->idle_slice_timer);
3918 cancel_work_sync(&cfqd->unplug_work);
3919}
3920
3921static void cfq_put_async_queues(struct cfq_data *cfqd)
3922{
3923 int i;
3924
3925 for (i = 0; i < IOPRIO_BE_NR; i++) {
3926 if (cfqd->async_cfqq[0][i])
3927 cfq_put_queue(cfqd->async_cfqq[0][i]);
3928 if (cfqd->async_cfqq[1][i])
3929 cfq_put_queue(cfqd->async_cfqq[1][i]);
3930 }
3931
3932 if (cfqd->async_idle_cfqq)
3933 cfq_put_queue(cfqd->async_idle_cfqq);
3934}
3935
3936static void cfq_exit_queue(struct elevator_queue *e)
3937{
3938 struct cfq_data *cfqd = e->elevator_data;
3939 struct request_queue *q = cfqd->queue;
3940
3941 cfq_shutdown_timer_wq(cfqd);
3942
3943 spin_lock_irq(q->queue_lock);
3944
3945 if (cfqd->active_queue)
3946 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3947
3948 cfq_put_async_queues(cfqd);
3949
3950 spin_unlock_irq(q->queue_lock);
3951
3952 cfq_shutdown_timer_wq(cfqd);
3953
3954#ifdef CONFIG_CFQ_GROUP_IOSCHED
3955 blkcg_deactivate_policy(q, &blkcg_policy_cfq);
3956#else
3957 kfree(cfqd->root_group);
3958#endif
3959 kfree(cfqd);
3960}
3961
3962static int cfq_init_queue(struct request_queue *q)
3963{
3964 struct cfq_data *cfqd;
3965 struct blkcg_gq *blkg __maybe_unused;
3966 int i, ret;
3967
3968 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3969 if (!cfqd)
3970 return -ENOMEM;
3971
3972 cfqd->queue = q;
3973 q->elevator->elevator_data = cfqd;
3974
3975 /* Init root service tree */
3976 cfqd->grp_service_tree = CFQ_RB_ROOT;
3977
3978 /* Init root group and prefer root group over other groups by default */
3979#ifdef CONFIG_CFQ_GROUP_IOSCHED
3980 ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
3981 if (ret)
3982 goto out_free;
3983
3984 cfqd->root_group = blkg_to_cfqg(q->root_blkg);
3985#else
3986 ret = -ENOMEM;
3987 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
3988 GFP_KERNEL, cfqd->queue->node);
3989 if (!cfqd->root_group)
3990 goto out_free;
3991
3992 cfq_init_cfqg_base(cfqd->root_group);
3993#endif
3994 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
3995
3996 /*
3997 * Not strictly needed (since RB_ROOT just clears the node and we
3998 * zeroed cfqd on alloc), but better be safe in case someone decides
3999 * to add magic to the rb code
4000 */
4001 for (i = 0; i < CFQ_PRIO_LISTS; i++)
4002 cfqd->prio_trees[i] = RB_ROOT;
4003
4004 /*
4005 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4006 * Grab a permanent reference to it, so that the normal code flow
4007 * will not attempt to free it. oom_cfqq is linked to root_group
4008 * but shouldn't hold a reference as it'll never be unlinked. Lose
4009 * the reference from linking right away.
4010 */
4011 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4012 cfqd->oom_cfqq.ref++;
4013
4014 spin_lock_irq(q->queue_lock);
4015 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4016 cfqg_put(cfqd->root_group);
4017 spin_unlock_irq(q->queue_lock);
4018
4019 init_timer(&cfqd->idle_slice_timer);
4020 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4021 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4022
4023 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4024
4025 cfqd->cfq_quantum = cfq_quantum;
4026 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4027 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4028 cfqd->cfq_back_max = cfq_back_max;
4029 cfqd->cfq_back_penalty = cfq_back_penalty;
4030 cfqd->cfq_slice[0] = cfq_slice_async;
4031 cfqd->cfq_slice[1] = cfq_slice_sync;
4032 cfqd->cfq_target_latency = cfq_target_latency;
4033 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4034 cfqd->cfq_slice_idle = cfq_slice_idle;
4035 cfqd->cfq_group_idle = cfq_group_idle;
4036 cfqd->cfq_latency = 1;
4037 cfqd->hw_tag = -1;
4038 /*
4039 * we optimistically start assuming sync ops weren't delayed in last
4040 * second, in order to have larger depth for async operations.
4041 */
4042 cfqd->last_delayed_sync = jiffies - HZ;
4043 return 0;
4044
4045out_free:
4046 kfree(cfqd);
4047 return ret;
4048}
4049
4050/*
4051 * sysfs parts below -->
4052 */
4053static ssize_t
4054cfq_var_show(unsigned int var, char *page)
4055{
4056 return sprintf(page, "%d\n", var);
4057}
4058
4059static ssize_t
4060cfq_var_store(unsigned int *var, const char *page, size_t count)
4061{
4062 char *p = (char *) page;
4063
4064 *var = simple_strtoul(p, &p, 10);
4065 return count;
4066}
4067
4068#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4069static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4070{ \
4071 struct cfq_data *cfqd = e->elevator_data; \
4072 unsigned int __data = __VAR; \
4073 if (__CONV) \
4074 __data = jiffies_to_msecs(__data); \
4075 return cfq_var_show(__data, (page)); \
4076}
4077SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4078SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4079SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4080SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4081SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4082SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4083SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4084SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4085SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4086SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4087SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4088SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
4089#undef SHOW_FUNCTION
4090
4091#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4092static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4093{ \
4094 struct cfq_data *cfqd = e->elevator_data; \
4095 unsigned int __data; \
4096 int ret = cfq_var_store(&__data, (page), count); \
4097 if (__data < (MIN)) \
4098 __data = (MIN); \
4099 else if (__data > (MAX)) \
4100 __data = (MAX); \
4101 if (__CONV) \
4102 *(__PTR) = msecs_to_jiffies(__data); \
4103 else \
4104 *(__PTR) = __data; \
4105 return ret; \
4106}
4107STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4108STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4109 UINT_MAX, 1);
4110STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4111 UINT_MAX, 1);
4112STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4113STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4114 UINT_MAX, 0);
4115STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4116STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4117STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4118STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4119STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4120 UINT_MAX, 0);
4121STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4122STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
4123#undef STORE_FUNCTION
4124
4125#define CFQ_ATTR(name) \
4126 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4127
4128static struct elv_fs_entry cfq_attrs[] = {
4129 CFQ_ATTR(quantum),
4130 CFQ_ATTR(fifo_expire_sync),
4131 CFQ_ATTR(fifo_expire_async),
4132 CFQ_ATTR(back_seek_max),
4133 CFQ_ATTR(back_seek_penalty),
4134 CFQ_ATTR(slice_sync),
4135 CFQ_ATTR(slice_async),
4136 CFQ_ATTR(slice_async_rq),
4137 CFQ_ATTR(slice_idle),
4138 CFQ_ATTR(group_idle),
4139 CFQ_ATTR(low_latency),
4140 CFQ_ATTR(target_latency),
4141 __ATTR_NULL
4142};
4143
4144static struct elevator_type iosched_cfq = {
4145 .ops = {
4146 .elevator_merge_fn = cfq_merge,
4147 .elevator_merged_fn = cfq_merged_request,
4148 .elevator_merge_req_fn = cfq_merged_requests,
4149 .elevator_allow_merge_fn = cfq_allow_merge,
4150 .elevator_bio_merged_fn = cfq_bio_merged,
4151 .elevator_dispatch_fn = cfq_dispatch_requests,
4152 .elevator_add_req_fn = cfq_insert_request,
4153 .elevator_activate_req_fn = cfq_activate_request,
4154 .elevator_deactivate_req_fn = cfq_deactivate_request,
4155 .elevator_completed_req_fn = cfq_completed_request,
4156 .elevator_former_req_fn = elv_rb_former_request,
4157 .elevator_latter_req_fn = elv_rb_latter_request,
4158 .elevator_init_icq_fn = cfq_init_icq,
4159 .elevator_exit_icq_fn = cfq_exit_icq,
4160 .elevator_set_req_fn = cfq_set_request,
4161 .elevator_put_req_fn = cfq_put_request,
4162 .elevator_may_queue_fn = cfq_may_queue,
4163 .elevator_init_fn = cfq_init_queue,
4164 .elevator_exit_fn = cfq_exit_queue,
4165 },
4166 .icq_size = sizeof(struct cfq_io_cq),
4167 .icq_align = __alignof__(struct cfq_io_cq),
4168 .elevator_attrs = cfq_attrs,
4169 .elevator_name = "cfq",
4170 .elevator_owner = THIS_MODULE,
4171};
4172
4173#ifdef CONFIG_CFQ_GROUP_IOSCHED
4174static struct blkcg_policy blkcg_policy_cfq = {
4175 .pd_size = sizeof(struct cfq_group),
4176 .cftypes = cfq_blkcg_files,
4177
4178 .pd_init_fn = cfq_pd_init,
4179 .pd_reset_stats_fn = cfq_pd_reset_stats,
4180};
4181#endif
4182
4183static int __init cfq_init(void)
4184{
4185 int ret;
4186
4187 /*
4188 * could be 0 on HZ < 1000 setups
4189 */
4190 if (!cfq_slice_async)
4191 cfq_slice_async = 1;
4192 if (!cfq_slice_idle)
4193 cfq_slice_idle = 1;
4194
4195#ifdef CONFIG_CFQ_GROUP_IOSCHED
4196 if (!cfq_group_idle)
4197 cfq_group_idle = 1;
4198
4199 ret = blkcg_policy_register(&blkcg_policy_cfq);
4200 if (ret)
4201 return ret;
4202#else
4203 cfq_group_idle = 0;
4204#endif
4205
4206 ret = -ENOMEM;
4207 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4208 if (!cfq_pool)
4209 goto err_pol_unreg;
4210
4211 ret = elv_register(&iosched_cfq);
4212 if (ret)
4213 goto err_free_pool;
4214
4215 return 0;
4216
4217err_free_pool:
4218 kmem_cache_destroy(cfq_pool);
4219err_pol_unreg:
4220#ifdef CONFIG_CFQ_GROUP_IOSCHED
4221 blkcg_policy_unregister(&blkcg_policy_cfq);
4222#endif
4223 return ret;
4224}
4225
4226static void __exit cfq_exit(void)
4227{
4228#ifdef CONFIG_CFQ_GROUP_IOSCHED
4229 blkcg_policy_unregister(&blkcg_policy_cfq);
4230#endif
4231 elv_unregister(&iosched_cfq);
4232 kmem_cache_destroy(cfq_pool);
4233}
4234
4235module_init(cfq_init);
4236module_exit(cfq_exit);
4237
4238MODULE_AUTHOR("Jens Axboe");
4239MODULE_LICENSE("GPL");
4240MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");
1/*
2 * CFQ, or complete fairness queueing, disk scheduler.
3 *
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
6 *
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
8 */
9#include <linux/module.h>
10#include <linux/slab.h>
11#include <linux/sched/clock.h>
12#include <linux/blkdev.h>
13#include <linux/elevator.h>
14#include <linux/ktime.h>
15#include <linux/rbtree.h>
16#include <linux/ioprio.h>
17#include <linux/blktrace_api.h>
18#include <linux/blk-cgroup.h>
19#include "blk.h"
20#include "blk-wbt.h"
21
22/*
23 * tunables
24 */
25/* max queue in one round of service */
26static const int cfq_quantum = 8;
27static const u64 cfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
28/* maximum backwards seek, in KiB */
29static const int cfq_back_max = 16 * 1024;
30/* penalty of a backwards seek */
31static const int cfq_back_penalty = 2;
32static const u64 cfq_slice_sync = NSEC_PER_SEC / 10;
33static u64 cfq_slice_async = NSEC_PER_SEC / 25;
34static const int cfq_slice_async_rq = 2;
35static u64 cfq_slice_idle = NSEC_PER_SEC / 125;
36static u64 cfq_group_idle = NSEC_PER_SEC / 125;
37static const u64 cfq_target_latency = (u64)NSEC_PER_SEC * 3/10; /* 300 ms */
38static const int cfq_hist_divisor = 4;
39
40/*
41 * offset from end of queue service tree for idle class
42 */
43#define CFQ_IDLE_DELAY (NSEC_PER_SEC / 5)
44/* offset from end of group service tree under time slice mode */
45#define CFQ_SLICE_MODE_GROUP_DELAY (NSEC_PER_SEC / 5)
46/* offset from end of group service under IOPS mode */
47#define CFQ_IOPS_MODE_GROUP_DELAY (HZ / 5)
48
49/*
50 * below this threshold, we consider thinktime immediate
51 */
52#define CFQ_MIN_TT (2 * NSEC_PER_SEC / HZ)
53
54#define CFQ_SLICE_SCALE (5)
55#define CFQ_HW_QUEUE_MIN (5)
56#define CFQ_SERVICE_SHIFT 12
57
58#define CFQQ_SEEK_THR (sector_t)(8 * 100)
59#define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
60#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
61#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
62
63#define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
64#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
65#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
66
67static struct kmem_cache *cfq_pool;
68
69#define CFQ_PRIO_LISTS IOPRIO_BE_NR
70#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
71#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
72
73#define sample_valid(samples) ((samples) > 80)
74#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
75
76/* blkio-related constants */
77#define CFQ_WEIGHT_LEGACY_MIN 10
78#define CFQ_WEIGHT_LEGACY_DFL 500
79#define CFQ_WEIGHT_LEGACY_MAX 1000
80
81struct cfq_ttime {
82 u64 last_end_request;
83
84 u64 ttime_total;
85 u64 ttime_mean;
86 unsigned long ttime_samples;
87};
88
89/*
90 * Most of our rbtree usage is for sorting with min extraction, so
91 * if we cache the leftmost node we don't have to walk down the tree
92 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
93 * move this into the elevator for the rq sorting as well.
94 */
95struct cfq_rb_root {
96 struct rb_root_cached rb;
97 struct rb_node *rb_rightmost;
98 unsigned count;
99 u64 min_vdisktime;
100 struct cfq_ttime ttime;
101};
102#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT_CACHED, \
103 .rb_rightmost = NULL, \
104 .ttime = {.last_end_request = ktime_get_ns(),},}
105
106/*
107 * Per process-grouping structure
108 */
109struct cfq_queue {
110 /* reference count */
111 int ref;
112 /* various state flags, see below */
113 unsigned int flags;
114 /* parent cfq_data */
115 struct cfq_data *cfqd;
116 /* service_tree member */
117 struct rb_node rb_node;
118 /* service_tree key */
119 u64 rb_key;
120 /* prio tree member */
121 struct rb_node p_node;
122 /* prio tree root we belong to, if any */
123 struct rb_root *p_root;
124 /* sorted list of pending requests */
125 struct rb_root sort_list;
126 /* if fifo isn't expired, next request to serve */
127 struct request *next_rq;
128 /* requests queued in sort_list */
129 int queued[2];
130 /* currently allocated requests */
131 int allocated[2];
132 /* fifo list of requests in sort_list */
133 struct list_head fifo;
134
135 /* time when queue got scheduled in to dispatch first request. */
136 u64 dispatch_start;
137 u64 allocated_slice;
138 u64 slice_dispatch;
139 /* time when first request from queue completed and slice started. */
140 u64 slice_start;
141 u64 slice_end;
142 s64 slice_resid;
143
144 /* pending priority requests */
145 int prio_pending;
146 /* number of requests that are on the dispatch list or inside driver */
147 int dispatched;
148
149 /* io prio of this group */
150 unsigned short ioprio, org_ioprio;
151 unsigned short ioprio_class, org_ioprio_class;
152
153 pid_t pid;
154
155 u32 seek_history;
156 sector_t last_request_pos;
157
158 struct cfq_rb_root *service_tree;
159 struct cfq_queue *new_cfqq;
160 struct cfq_group *cfqg;
161 /* Number of sectors dispatched from queue in single dispatch round */
162 unsigned long nr_sectors;
163};
164
165/*
166 * First index in the service_trees.
167 * IDLE is handled separately, so it has negative index
168 */
169enum wl_class_t {
170 BE_WORKLOAD = 0,
171 RT_WORKLOAD = 1,
172 IDLE_WORKLOAD = 2,
173 CFQ_PRIO_NR,
174};
175
176/*
177 * Second index in the service_trees.
178 */
179enum wl_type_t {
180 ASYNC_WORKLOAD = 0,
181 SYNC_NOIDLE_WORKLOAD = 1,
182 SYNC_WORKLOAD = 2
183};
184
185struct cfqg_stats {
186#ifdef CONFIG_CFQ_GROUP_IOSCHED
187 /* number of ios merged */
188 struct blkg_rwstat merged;
189 /* total time spent on device in ns, may not be accurate w/ queueing */
190 struct blkg_rwstat service_time;
191 /* total time spent waiting in scheduler queue in ns */
192 struct blkg_rwstat wait_time;
193 /* number of IOs queued up */
194 struct blkg_rwstat queued;
195 /* total disk time and nr sectors dispatched by this group */
196 struct blkg_stat time;
197#ifdef CONFIG_DEBUG_BLK_CGROUP
198 /* time not charged to this cgroup */
199 struct blkg_stat unaccounted_time;
200 /* sum of number of ios queued across all samples */
201 struct blkg_stat avg_queue_size_sum;
202 /* count of samples taken for average */
203 struct blkg_stat avg_queue_size_samples;
204 /* how many times this group has been removed from service tree */
205 struct blkg_stat dequeue;
206 /* total time spent waiting for it to be assigned a timeslice. */
207 struct blkg_stat group_wait_time;
208 /* time spent idling for this blkcg_gq */
209 struct blkg_stat idle_time;
210 /* total time with empty current active q with other requests queued */
211 struct blkg_stat empty_time;
212 /* fields after this shouldn't be cleared on stat reset */
213 uint64_t start_group_wait_time;
214 uint64_t start_idle_time;
215 uint64_t start_empty_time;
216 uint16_t flags;
217#endif /* CONFIG_DEBUG_BLK_CGROUP */
218#endif /* CONFIG_CFQ_GROUP_IOSCHED */
219};
220
221/* Per-cgroup data */
222struct cfq_group_data {
223 /* must be the first member */
224 struct blkcg_policy_data cpd;
225
226 unsigned int weight;
227 unsigned int leaf_weight;
228};
229
230/* This is per cgroup per device grouping structure */
231struct cfq_group {
232 /* must be the first member */
233 struct blkg_policy_data pd;
234
235 /* group service_tree member */
236 struct rb_node rb_node;
237
238 /* group service_tree key */
239 u64 vdisktime;
240
241 /*
242 * The number of active cfqgs and sum of their weights under this
243 * cfqg. This covers this cfqg's leaf_weight and all children's
244 * weights, but does not cover weights of further descendants.
245 *
246 * If a cfqg is on the service tree, it's active. An active cfqg
247 * also activates its parent and contributes to the children_weight
248 * of the parent.
249 */
250 int nr_active;
251 unsigned int children_weight;
252
253 /*
254 * vfraction is the fraction of vdisktime that the tasks in this
255 * cfqg are entitled to. This is determined by compounding the
256 * ratios walking up from this cfqg to the root.
257 *
258 * It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all
259 * vfractions on a service tree is approximately 1. The sum may
260 * deviate a bit due to rounding errors and fluctuations caused by
261 * cfqgs entering and leaving the service tree.
262 */
263 unsigned int vfraction;
264
265 /*
266 * There are two weights - (internal) weight is the weight of this
267 * cfqg against the sibling cfqgs. leaf_weight is the wight of
268 * this cfqg against the child cfqgs. For the root cfqg, both
269 * weights are kept in sync for backward compatibility.
270 */
271 unsigned int weight;
272 unsigned int new_weight;
273 unsigned int dev_weight;
274
275 unsigned int leaf_weight;
276 unsigned int new_leaf_weight;
277 unsigned int dev_leaf_weight;
278
279 /* number of cfqq currently on this group */
280 int nr_cfqq;
281
282 /*
283 * Per group busy queues average. Useful for workload slice calc. We
284 * create the array for each prio class but at run time it is used
285 * only for RT and BE class and slot for IDLE class remains unused.
286 * This is primarily done to avoid confusion and a gcc warning.
287 */
288 unsigned int busy_queues_avg[CFQ_PRIO_NR];
289 /*
290 * rr lists of queues with requests. We maintain service trees for
291 * RT and BE classes. These trees are subdivided in subclasses
292 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
293 * class there is no subclassification and all the cfq queues go on
294 * a single tree service_tree_idle.
295 * Counts are embedded in the cfq_rb_root
296 */
297 struct cfq_rb_root service_trees[2][3];
298 struct cfq_rb_root service_tree_idle;
299
300 u64 saved_wl_slice;
301 enum wl_type_t saved_wl_type;
302 enum wl_class_t saved_wl_class;
303
304 /* number of requests that are on the dispatch list or inside driver */
305 int dispatched;
306 struct cfq_ttime ttime;
307 struct cfqg_stats stats; /* stats for this cfqg */
308
309 /* async queue for each priority case */
310 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
311 struct cfq_queue *async_idle_cfqq;
312
313};
314
315struct cfq_io_cq {
316 struct io_cq icq; /* must be the first member */
317 struct cfq_queue *cfqq[2];
318 struct cfq_ttime ttime;
319 int ioprio; /* the current ioprio */
320#ifdef CONFIG_CFQ_GROUP_IOSCHED
321 uint64_t blkcg_serial_nr; /* the current blkcg serial */
322#endif
323};
324
325/*
326 * Per block device queue structure
327 */
328struct cfq_data {
329 struct request_queue *queue;
330 /* Root service tree for cfq_groups */
331 struct cfq_rb_root grp_service_tree;
332 struct cfq_group *root_group;
333
334 /*
335 * The priority currently being served
336 */
337 enum wl_class_t serving_wl_class;
338 enum wl_type_t serving_wl_type;
339 u64 workload_expires;
340 struct cfq_group *serving_group;
341
342 /*
343 * Each priority tree is sorted by next_request position. These
344 * trees are used when determining if two or more queues are
345 * interleaving requests (see cfq_close_cooperator).
346 */
347 struct rb_root prio_trees[CFQ_PRIO_LISTS];
348
349 unsigned int busy_queues;
350 unsigned int busy_sync_queues;
351
352 int rq_in_driver;
353 int rq_in_flight[2];
354
355 /*
356 * queue-depth detection
357 */
358 int rq_queued;
359 int hw_tag;
360 /*
361 * hw_tag can be
362 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
363 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
364 * 0 => no NCQ
365 */
366 int hw_tag_est_depth;
367 unsigned int hw_tag_samples;
368
369 /*
370 * idle window management
371 */
372 struct hrtimer idle_slice_timer;
373 struct work_struct unplug_work;
374
375 struct cfq_queue *active_queue;
376 struct cfq_io_cq *active_cic;
377
378 sector_t last_position;
379
380 /*
381 * tunables, see top of file
382 */
383 unsigned int cfq_quantum;
384 unsigned int cfq_back_penalty;
385 unsigned int cfq_back_max;
386 unsigned int cfq_slice_async_rq;
387 unsigned int cfq_latency;
388 u64 cfq_fifo_expire[2];
389 u64 cfq_slice[2];
390 u64 cfq_slice_idle;
391 u64 cfq_group_idle;
392 u64 cfq_target_latency;
393
394 /*
395 * Fallback dummy cfqq for extreme OOM conditions
396 */
397 struct cfq_queue oom_cfqq;
398
399 u64 last_delayed_sync;
400};
401
402static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
403static void cfq_put_queue(struct cfq_queue *cfqq);
404
405static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
406 enum wl_class_t class,
407 enum wl_type_t type)
408{
409 if (!cfqg)
410 return NULL;
411
412 if (class == IDLE_WORKLOAD)
413 return &cfqg->service_tree_idle;
414
415 return &cfqg->service_trees[class][type];
416}
417
418enum cfqq_state_flags {
419 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
420 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
421 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
422 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
423 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
424 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
425 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
426 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
427 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
428 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
429 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
430 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
431 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
432};
433
434#define CFQ_CFQQ_FNS(name) \
435static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
436{ \
437 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
438} \
439static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
440{ \
441 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
442} \
443static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
444{ \
445 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
446}
447
448CFQ_CFQQ_FNS(on_rr);
449CFQ_CFQQ_FNS(wait_request);
450CFQ_CFQQ_FNS(must_dispatch);
451CFQ_CFQQ_FNS(must_alloc_slice);
452CFQ_CFQQ_FNS(fifo_expire);
453CFQ_CFQQ_FNS(idle_window);
454CFQ_CFQQ_FNS(prio_changed);
455CFQ_CFQQ_FNS(slice_new);
456CFQ_CFQQ_FNS(sync);
457CFQ_CFQQ_FNS(coop);
458CFQ_CFQQ_FNS(split_coop);
459CFQ_CFQQ_FNS(deep);
460CFQ_CFQQ_FNS(wait_busy);
461#undef CFQ_CFQQ_FNS
462
463#if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
464
465/* cfqg stats flags */
466enum cfqg_stats_flags {
467 CFQG_stats_waiting = 0,
468 CFQG_stats_idling,
469 CFQG_stats_empty,
470};
471
472#define CFQG_FLAG_FNS(name) \
473static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
474{ \
475 stats->flags |= (1 << CFQG_stats_##name); \
476} \
477static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
478{ \
479 stats->flags &= ~(1 << CFQG_stats_##name); \
480} \
481static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
482{ \
483 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
484} \
485
486CFQG_FLAG_FNS(waiting)
487CFQG_FLAG_FNS(idling)
488CFQG_FLAG_FNS(empty)
489#undef CFQG_FLAG_FNS
490
491/* This should be called with the queue_lock held. */
492static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
493{
494 unsigned long long now;
495
496 if (!cfqg_stats_waiting(stats))
497 return;
498
499 now = sched_clock();
500 if (time_after64(now, stats->start_group_wait_time))
501 blkg_stat_add(&stats->group_wait_time,
502 now - stats->start_group_wait_time);
503 cfqg_stats_clear_waiting(stats);
504}
505
506/* This should be called with the queue_lock held. */
507static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
508 struct cfq_group *curr_cfqg)
509{
510 struct cfqg_stats *stats = &cfqg->stats;
511
512 if (cfqg_stats_waiting(stats))
513 return;
514 if (cfqg == curr_cfqg)
515 return;
516 stats->start_group_wait_time = sched_clock();
517 cfqg_stats_mark_waiting(stats);
518}
519
520/* This should be called with the queue_lock held. */
521static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
522{
523 unsigned long long now;
524
525 if (!cfqg_stats_empty(stats))
526 return;
527
528 now = sched_clock();
529 if (time_after64(now, stats->start_empty_time))
530 blkg_stat_add(&stats->empty_time,
531 now - stats->start_empty_time);
532 cfqg_stats_clear_empty(stats);
533}
534
535static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
536{
537 blkg_stat_add(&cfqg->stats.dequeue, 1);
538}
539
540static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
541{
542 struct cfqg_stats *stats = &cfqg->stats;
543
544 if (blkg_rwstat_total(&stats->queued))
545 return;
546
547 /*
548 * group is already marked empty. This can happen if cfqq got new
549 * request in parent group and moved to this group while being added
550 * to service tree. Just ignore the event and move on.
551 */
552 if (cfqg_stats_empty(stats))
553 return;
554
555 stats->start_empty_time = sched_clock();
556 cfqg_stats_mark_empty(stats);
557}
558
559static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
560{
561 struct cfqg_stats *stats = &cfqg->stats;
562
563 if (cfqg_stats_idling(stats)) {
564 unsigned long long now = sched_clock();
565
566 if (time_after64(now, stats->start_idle_time))
567 blkg_stat_add(&stats->idle_time,
568 now - stats->start_idle_time);
569 cfqg_stats_clear_idling(stats);
570 }
571}
572
573static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
574{
575 struct cfqg_stats *stats = &cfqg->stats;
576
577 BUG_ON(cfqg_stats_idling(stats));
578
579 stats->start_idle_time = sched_clock();
580 cfqg_stats_mark_idling(stats);
581}
582
583static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
584{
585 struct cfqg_stats *stats = &cfqg->stats;
586
587 blkg_stat_add(&stats->avg_queue_size_sum,
588 blkg_rwstat_total(&stats->queued));
589 blkg_stat_add(&stats->avg_queue_size_samples, 1);
590 cfqg_stats_update_group_wait_time(stats);
591}
592
593#else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
594
595static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
596static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
597static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
598static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
599static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
600static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
601static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
602
603#endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
604
605#ifdef CONFIG_CFQ_GROUP_IOSCHED
606
607static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
608{
609 return pd ? container_of(pd, struct cfq_group, pd) : NULL;
610}
611
612static struct cfq_group_data
613*cpd_to_cfqgd(struct blkcg_policy_data *cpd)
614{
615 return cpd ? container_of(cpd, struct cfq_group_data, cpd) : NULL;
616}
617
618static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
619{
620 return pd_to_blkg(&cfqg->pd);
621}
622
623static struct blkcg_policy blkcg_policy_cfq;
624
625static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
626{
627 return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
628}
629
630static struct cfq_group_data *blkcg_to_cfqgd(struct blkcg *blkcg)
631{
632 return cpd_to_cfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_cfq));
633}
634
635static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
636{
637 struct blkcg_gq *pblkg = cfqg_to_blkg(cfqg)->parent;
638
639 return pblkg ? blkg_to_cfqg(pblkg) : NULL;
640}
641
642static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
643 struct cfq_group *ancestor)
644{
645 return cgroup_is_descendant(cfqg_to_blkg(cfqg)->blkcg->css.cgroup,
646 cfqg_to_blkg(ancestor)->blkcg->css.cgroup);
647}
648
649static inline void cfqg_get(struct cfq_group *cfqg)
650{
651 return blkg_get(cfqg_to_blkg(cfqg));
652}
653
654static inline void cfqg_put(struct cfq_group *cfqg)
655{
656 return blkg_put(cfqg_to_blkg(cfqg));
657}
658
659#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
660 blk_add_cgroup_trace_msg((cfqd)->queue, \
661 cfqg_to_blkg((cfqq)->cfqg)->blkcg, \
662 "cfq%d%c%c " fmt, (cfqq)->pid, \
663 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
664 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
665 ##args); \
666} while (0)
667
668#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
669 blk_add_cgroup_trace_msg((cfqd)->queue, \
670 cfqg_to_blkg(cfqg)->blkcg, fmt, ##args); \
671} while (0)
672
673static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
674 struct cfq_group *curr_cfqg,
675 unsigned int op)
676{
677 blkg_rwstat_add(&cfqg->stats.queued, op, 1);
678 cfqg_stats_end_empty_time(&cfqg->stats);
679 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
680}
681
682static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
683 uint64_t time, unsigned long unaccounted_time)
684{
685 blkg_stat_add(&cfqg->stats.time, time);
686#ifdef CONFIG_DEBUG_BLK_CGROUP
687 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
688#endif
689}
690
691static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg,
692 unsigned int op)
693{
694 blkg_rwstat_add(&cfqg->stats.queued, op, -1);
695}
696
697static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg,
698 unsigned int op)
699{
700 blkg_rwstat_add(&cfqg->stats.merged, op, 1);
701}
702
703static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
704 uint64_t start_time, uint64_t io_start_time,
705 unsigned int op)
706{
707 struct cfqg_stats *stats = &cfqg->stats;
708 unsigned long long now = sched_clock();
709
710 if (time_after64(now, io_start_time))
711 blkg_rwstat_add(&stats->service_time, op, now - io_start_time);
712 if (time_after64(io_start_time, start_time))
713 blkg_rwstat_add(&stats->wait_time, op,
714 io_start_time - start_time);
715}
716
717/* @stats = 0 */
718static void cfqg_stats_reset(struct cfqg_stats *stats)
719{
720 /* queued stats shouldn't be cleared */
721 blkg_rwstat_reset(&stats->merged);
722 blkg_rwstat_reset(&stats->service_time);
723 blkg_rwstat_reset(&stats->wait_time);
724 blkg_stat_reset(&stats->time);
725#ifdef CONFIG_DEBUG_BLK_CGROUP
726 blkg_stat_reset(&stats->unaccounted_time);
727 blkg_stat_reset(&stats->avg_queue_size_sum);
728 blkg_stat_reset(&stats->avg_queue_size_samples);
729 blkg_stat_reset(&stats->dequeue);
730 blkg_stat_reset(&stats->group_wait_time);
731 blkg_stat_reset(&stats->idle_time);
732 blkg_stat_reset(&stats->empty_time);
733#endif
734}
735
736/* @to += @from */
737static void cfqg_stats_add_aux(struct cfqg_stats *to, struct cfqg_stats *from)
738{
739 /* queued stats shouldn't be cleared */
740 blkg_rwstat_add_aux(&to->merged, &from->merged);
741 blkg_rwstat_add_aux(&to->service_time, &from->service_time);
742 blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
743 blkg_stat_add_aux(&from->time, &from->time);
744#ifdef CONFIG_DEBUG_BLK_CGROUP
745 blkg_stat_add_aux(&to->unaccounted_time, &from->unaccounted_time);
746 blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
747 blkg_stat_add_aux(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
748 blkg_stat_add_aux(&to->dequeue, &from->dequeue);
749 blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
750 blkg_stat_add_aux(&to->idle_time, &from->idle_time);
751 blkg_stat_add_aux(&to->empty_time, &from->empty_time);
752#endif
753}
754
755/*
756 * Transfer @cfqg's stats to its parent's aux counts so that the ancestors'
757 * recursive stats can still account for the amount used by this cfqg after
758 * it's gone.
759 */
760static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
761{
762 struct cfq_group *parent = cfqg_parent(cfqg);
763
764 lockdep_assert_held(cfqg_to_blkg(cfqg)->q->queue_lock);
765
766 if (unlikely(!parent))
767 return;
768
769 cfqg_stats_add_aux(&parent->stats, &cfqg->stats);
770 cfqg_stats_reset(&cfqg->stats);
771}
772
773#else /* CONFIG_CFQ_GROUP_IOSCHED */
774
775static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
776static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
777 struct cfq_group *ancestor)
778{
779 return true;
780}
781static inline void cfqg_get(struct cfq_group *cfqg) { }
782static inline void cfqg_put(struct cfq_group *cfqg) { }
783
784#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
785 blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid, \
786 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
787 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
788 ##args)
789#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
790
791static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
792 struct cfq_group *curr_cfqg, unsigned int op) { }
793static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
794 uint64_t time, unsigned long unaccounted_time) { }
795static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg,
796 unsigned int op) { }
797static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg,
798 unsigned int op) { }
799static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
800 uint64_t start_time, uint64_t io_start_time,
801 unsigned int op) { }
802
803#endif /* CONFIG_CFQ_GROUP_IOSCHED */
804
805#define cfq_log(cfqd, fmt, args...) \
806 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
807
808/* Traverses through cfq group service trees */
809#define for_each_cfqg_st(cfqg, i, j, st) \
810 for (i = 0; i <= IDLE_WORKLOAD; i++) \
811 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
812 : &cfqg->service_tree_idle; \
813 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
814 (i == IDLE_WORKLOAD && j == 0); \
815 j++, st = i < IDLE_WORKLOAD ? \
816 &cfqg->service_trees[i][j]: NULL) \
817
818static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
819 struct cfq_ttime *ttime, bool group_idle)
820{
821 u64 slice;
822 if (!sample_valid(ttime->ttime_samples))
823 return false;
824 if (group_idle)
825 slice = cfqd->cfq_group_idle;
826 else
827 slice = cfqd->cfq_slice_idle;
828 return ttime->ttime_mean > slice;
829}
830
831static inline bool iops_mode(struct cfq_data *cfqd)
832{
833 /*
834 * If we are not idling on queues and it is a NCQ drive, parallel
835 * execution of requests is on and measuring time is not possible
836 * in most of the cases until and unless we drive shallower queue
837 * depths and that becomes a performance bottleneck. In such cases
838 * switch to start providing fairness in terms of number of IOs.
839 */
840 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
841 return true;
842 else
843 return false;
844}
845
846static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq)
847{
848 if (cfq_class_idle(cfqq))
849 return IDLE_WORKLOAD;
850 if (cfq_class_rt(cfqq))
851 return RT_WORKLOAD;
852 return BE_WORKLOAD;
853}
854
855
856static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
857{
858 if (!cfq_cfqq_sync(cfqq))
859 return ASYNC_WORKLOAD;
860 if (!cfq_cfqq_idle_window(cfqq))
861 return SYNC_NOIDLE_WORKLOAD;
862 return SYNC_WORKLOAD;
863}
864
865static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class,
866 struct cfq_data *cfqd,
867 struct cfq_group *cfqg)
868{
869 if (wl_class == IDLE_WORKLOAD)
870 return cfqg->service_tree_idle.count;
871
872 return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count +
873 cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count +
874 cfqg->service_trees[wl_class][SYNC_WORKLOAD].count;
875}
876
877static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
878 struct cfq_group *cfqg)
879{
880 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count +
881 cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
882}
883
884static void cfq_dispatch_insert(struct request_queue *, struct request *);
885static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
886 struct cfq_io_cq *cic, struct bio *bio);
887
888static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
889{
890 /* cic->icq is the first member, %NULL will convert to %NULL */
891 return container_of(icq, struct cfq_io_cq, icq);
892}
893
894static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
895 struct io_context *ioc)
896{
897 if (ioc)
898 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
899 return NULL;
900}
901
902static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
903{
904 return cic->cfqq[is_sync];
905}
906
907static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
908 bool is_sync)
909{
910 cic->cfqq[is_sync] = cfqq;
911}
912
913static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
914{
915 return cic->icq.q->elevator->elevator_data;
916}
917
918/*
919 * scheduler run of queue, if there are requests pending and no one in the
920 * driver that will restart queueing
921 */
922static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
923{
924 if (cfqd->busy_queues) {
925 cfq_log(cfqd, "schedule dispatch");
926 kblockd_schedule_work(&cfqd->unplug_work);
927 }
928}
929
930/*
931 * Scale schedule slice based on io priority. Use the sync time slice only
932 * if a queue is marked sync and has sync io queued. A sync queue with async
933 * io only, should not get full sync slice length.
934 */
935static inline u64 cfq_prio_slice(struct cfq_data *cfqd, bool sync,
936 unsigned short prio)
937{
938 u64 base_slice = cfqd->cfq_slice[sync];
939 u64 slice = div_u64(base_slice, CFQ_SLICE_SCALE);
940
941 WARN_ON(prio >= IOPRIO_BE_NR);
942
943 return base_slice + (slice * (4 - prio));
944}
945
946static inline u64
947cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
948{
949 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
950}
951
952/**
953 * cfqg_scale_charge - scale disk time charge according to cfqg weight
954 * @charge: disk time being charged
955 * @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
956 *
957 * Scale @charge according to @vfraction, which is in range (0, 1]. The
958 * scaling is inversely proportional.
959 *
960 * scaled = charge / vfraction
961 *
962 * The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
963 */
964static inline u64 cfqg_scale_charge(u64 charge,
965 unsigned int vfraction)
966{
967 u64 c = charge << CFQ_SERVICE_SHIFT; /* make it fixed point */
968
969 /* charge / vfraction */
970 c <<= CFQ_SERVICE_SHIFT;
971 return div_u64(c, vfraction);
972}
973
974static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
975{
976 s64 delta = (s64)(vdisktime - min_vdisktime);
977 if (delta > 0)
978 min_vdisktime = vdisktime;
979
980 return min_vdisktime;
981}
982
983static void update_min_vdisktime(struct cfq_rb_root *st)
984{
985 if (!RB_EMPTY_ROOT(&st->rb.rb_root)) {
986 struct cfq_group *cfqg = rb_entry_cfqg(st->rb.rb_leftmost);
987
988 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
989 cfqg->vdisktime);
990 }
991}
992
993/*
994 * get averaged number of queues of RT/BE priority.
995 * average is updated, with a formula that gives more weight to higher numbers,
996 * to quickly follows sudden increases and decrease slowly
997 */
998
999static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
1000 struct cfq_group *cfqg, bool rt)
1001{
1002 unsigned min_q, max_q;
1003 unsigned mult = cfq_hist_divisor - 1;
1004 unsigned round = cfq_hist_divisor / 2;
1005 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
1006
1007 min_q = min(cfqg->busy_queues_avg[rt], busy);
1008 max_q = max(cfqg->busy_queues_avg[rt], busy);
1009 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
1010 cfq_hist_divisor;
1011 return cfqg->busy_queues_avg[rt];
1012}
1013
1014static inline u64
1015cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
1016{
1017 return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT;
1018}
1019
1020static inline u64
1021cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1022{
1023 u64 slice = cfq_prio_to_slice(cfqd, cfqq);
1024 if (cfqd->cfq_latency) {
1025 /*
1026 * interested queues (we consider only the ones with the same
1027 * priority class in the cfq group)
1028 */
1029 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
1030 cfq_class_rt(cfqq));
1031 u64 sync_slice = cfqd->cfq_slice[1];
1032 u64 expect_latency = sync_slice * iq;
1033 u64 group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
1034
1035 if (expect_latency > group_slice) {
1036 u64 base_low_slice = 2 * cfqd->cfq_slice_idle;
1037 u64 low_slice;
1038
1039 /* scale low_slice according to IO priority
1040 * and sync vs async */
1041 low_slice = div64_u64(base_low_slice*slice, sync_slice);
1042 low_slice = min(slice, low_slice);
1043 /* the adapted slice value is scaled to fit all iqs
1044 * into the target latency */
1045 slice = div64_u64(slice*group_slice, expect_latency);
1046 slice = max(slice, low_slice);
1047 }
1048 }
1049 return slice;
1050}
1051
1052static inline void
1053cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1054{
1055 u64 slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
1056 u64 now = ktime_get_ns();
1057
1058 cfqq->slice_start = now;
1059 cfqq->slice_end = now + slice;
1060 cfqq->allocated_slice = slice;
1061 cfq_log_cfqq(cfqd, cfqq, "set_slice=%llu", cfqq->slice_end - now);
1062}
1063
1064/*
1065 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
1066 * isn't valid until the first request from the dispatch is activated
1067 * and the slice time set.
1068 */
1069static inline bool cfq_slice_used(struct cfq_queue *cfqq)
1070{
1071 if (cfq_cfqq_slice_new(cfqq))
1072 return false;
1073 if (ktime_get_ns() < cfqq->slice_end)
1074 return false;
1075
1076 return true;
1077}
1078
1079/*
1080 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
1081 * We choose the request that is closest to the head right now. Distance
1082 * behind the head is penalized and only allowed to a certain extent.
1083 */
1084static struct request *
1085cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
1086{
1087 sector_t s1, s2, d1 = 0, d2 = 0;
1088 unsigned long back_max;
1089#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
1090#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
1091 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
1092
1093 if (rq1 == NULL || rq1 == rq2)
1094 return rq2;
1095 if (rq2 == NULL)
1096 return rq1;
1097
1098 if (rq_is_sync(rq1) != rq_is_sync(rq2))
1099 return rq_is_sync(rq1) ? rq1 : rq2;
1100
1101 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
1102 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
1103
1104 s1 = blk_rq_pos(rq1);
1105 s2 = blk_rq_pos(rq2);
1106
1107 /*
1108 * by definition, 1KiB is 2 sectors
1109 */
1110 back_max = cfqd->cfq_back_max * 2;
1111
1112 /*
1113 * Strict one way elevator _except_ in the case where we allow
1114 * short backward seeks which are biased as twice the cost of a
1115 * similar forward seek.
1116 */
1117 if (s1 >= last)
1118 d1 = s1 - last;
1119 else if (s1 + back_max >= last)
1120 d1 = (last - s1) * cfqd->cfq_back_penalty;
1121 else
1122 wrap |= CFQ_RQ1_WRAP;
1123
1124 if (s2 >= last)
1125 d2 = s2 - last;
1126 else if (s2 + back_max >= last)
1127 d2 = (last - s2) * cfqd->cfq_back_penalty;
1128 else
1129 wrap |= CFQ_RQ2_WRAP;
1130
1131 /* Found required data */
1132
1133 /*
1134 * By doing switch() on the bit mask "wrap" we avoid having to
1135 * check two variables for all permutations: --> faster!
1136 */
1137 switch (wrap) {
1138 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1139 if (d1 < d2)
1140 return rq1;
1141 else if (d2 < d1)
1142 return rq2;
1143 else {
1144 if (s1 >= s2)
1145 return rq1;
1146 else
1147 return rq2;
1148 }
1149
1150 case CFQ_RQ2_WRAP:
1151 return rq1;
1152 case CFQ_RQ1_WRAP:
1153 return rq2;
1154 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1155 default:
1156 /*
1157 * Since both rqs are wrapped,
1158 * start with the one that's further behind head
1159 * (--> only *one* back seek required),
1160 * since back seek takes more time than forward.
1161 */
1162 if (s1 <= s2)
1163 return rq1;
1164 else
1165 return rq2;
1166 }
1167}
1168
1169static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1170{
1171 /* Service tree is empty */
1172 if (!root->count)
1173 return NULL;
1174
1175 return rb_entry(rb_first_cached(&root->rb), struct cfq_queue, rb_node);
1176}
1177
1178static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1179{
1180 return rb_entry_cfqg(rb_first_cached(&root->rb));
1181}
1182
1183static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1184{
1185 if (root->rb_rightmost == n)
1186 root->rb_rightmost = rb_prev(n);
1187
1188 rb_erase_cached(n, &root->rb);
1189 RB_CLEAR_NODE(n);
1190
1191 --root->count;
1192}
1193
1194/*
1195 * would be nice to take fifo expire time into account as well
1196 */
1197static struct request *
1198cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1199 struct request *last)
1200{
1201 struct rb_node *rbnext = rb_next(&last->rb_node);
1202 struct rb_node *rbprev = rb_prev(&last->rb_node);
1203 struct request *next = NULL, *prev = NULL;
1204
1205 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1206
1207 if (rbprev)
1208 prev = rb_entry_rq(rbprev);
1209
1210 if (rbnext)
1211 next = rb_entry_rq(rbnext);
1212 else {
1213 rbnext = rb_first(&cfqq->sort_list);
1214 if (rbnext && rbnext != &last->rb_node)
1215 next = rb_entry_rq(rbnext);
1216 }
1217
1218 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1219}
1220
1221static u64 cfq_slice_offset(struct cfq_data *cfqd,
1222 struct cfq_queue *cfqq)
1223{
1224 /*
1225 * just an approximation, should be ok.
1226 */
1227 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1228 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1229}
1230
1231static inline s64
1232cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1233{
1234 return cfqg->vdisktime - st->min_vdisktime;
1235}
1236
1237static void
1238__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1239{
1240 struct rb_node **node = &st->rb.rb_root.rb_node;
1241 struct rb_node *parent = NULL;
1242 struct cfq_group *__cfqg;
1243 s64 key = cfqg_key(st, cfqg);
1244 bool leftmost = true, rightmost = true;
1245
1246 while (*node != NULL) {
1247 parent = *node;
1248 __cfqg = rb_entry_cfqg(parent);
1249
1250 if (key < cfqg_key(st, __cfqg)) {
1251 node = &parent->rb_left;
1252 rightmost = false;
1253 } else {
1254 node = &parent->rb_right;
1255 leftmost = false;
1256 }
1257 }
1258
1259 if (rightmost)
1260 st->rb_rightmost = &cfqg->rb_node;
1261
1262 rb_link_node(&cfqg->rb_node, parent, node);
1263 rb_insert_color_cached(&cfqg->rb_node, &st->rb, leftmost);
1264}
1265
1266/*
1267 * This has to be called only on activation of cfqg
1268 */
1269static void
1270cfq_update_group_weight(struct cfq_group *cfqg)
1271{
1272 if (cfqg->new_weight) {
1273 cfqg->weight = cfqg->new_weight;
1274 cfqg->new_weight = 0;
1275 }
1276}
1277
1278static void
1279cfq_update_group_leaf_weight(struct cfq_group *cfqg)
1280{
1281 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1282
1283 if (cfqg->new_leaf_weight) {
1284 cfqg->leaf_weight = cfqg->new_leaf_weight;
1285 cfqg->new_leaf_weight = 0;
1286 }
1287}
1288
1289static void
1290cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1291{
1292 unsigned int vfr = 1 << CFQ_SERVICE_SHIFT; /* start with 1 */
1293 struct cfq_group *pos = cfqg;
1294 struct cfq_group *parent;
1295 bool propagate;
1296
1297 /* add to the service tree */
1298 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1299
1300 /*
1301 * Update leaf_weight. We cannot update weight at this point
1302 * because cfqg might already have been activated and is
1303 * contributing its current weight to the parent's child_weight.
1304 */
1305 cfq_update_group_leaf_weight(cfqg);
1306 __cfq_group_service_tree_add(st, cfqg);
1307
1308 /*
1309 * Activate @cfqg and calculate the portion of vfraction @cfqg is
1310 * entitled to. vfraction is calculated by walking the tree
1311 * towards the root calculating the fraction it has at each level.
1312 * The compounded ratio is how much vfraction @cfqg owns.
1313 *
1314 * Start with the proportion tasks in this cfqg has against active
1315 * children cfqgs - its leaf_weight against children_weight.
1316 */
1317 propagate = !pos->nr_active++;
1318 pos->children_weight += pos->leaf_weight;
1319 vfr = vfr * pos->leaf_weight / pos->children_weight;
1320
1321 /*
1322 * Compound ->weight walking up the tree. Both activation and
1323 * vfraction calculation are done in the same loop. Propagation
1324 * stops once an already activated node is met. vfraction
1325 * calculation should always continue to the root.
1326 */
1327 while ((parent = cfqg_parent(pos))) {
1328 if (propagate) {
1329 cfq_update_group_weight(pos);
1330 propagate = !parent->nr_active++;
1331 parent->children_weight += pos->weight;
1332 }
1333 vfr = vfr * pos->weight / parent->children_weight;
1334 pos = parent;
1335 }
1336
1337 cfqg->vfraction = max_t(unsigned, vfr, 1);
1338}
1339
1340static inline u64 cfq_get_cfqg_vdisktime_delay(struct cfq_data *cfqd)
1341{
1342 if (!iops_mode(cfqd))
1343 return CFQ_SLICE_MODE_GROUP_DELAY;
1344 else
1345 return CFQ_IOPS_MODE_GROUP_DELAY;
1346}
1347
1348static void
1349cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1350{
1351 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1352 struct cfq_group *__cfqg;
1353 struct rb_node *n;
1354
1355 cfqg->nr_cfqq++;
1356 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1357 return;
1358
1359 /*
1360 * Currently put the group at the end. Later implement something
1361 * so that groups get lesser vtime based on their weights, so that
1362 * if group does not loose all if it was not continuously backlogged.
1363 */
1364 n = st->rb_rightmost;
1365 if (n) {
1366 __cfqg = rb_entry_cfqg(n);
1367 cfqg->vdisktime = __cfqg->vdisktime +
1368 cfq_get_cfqg_vdisktime_delay(cfqd);
1369 } else
1370 cfqg->vdisktime = st->min_vdisktime;
1371 cfq_group_service_tree_add(st, cfqg);
1372}
1373
1374static void
1375cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1376{
1377 struct cfq_group *pos = cfqg;
1378 bool propagate;
1379
1380 /*
1381 * Undo activation from cfq_group_service_tree_add(). Deactivate
1382 * @cfqg and propagate deactivation upwards.
1383 */
1384 propagate = !--pos->nr_active;
1385 pos->children_weight -= pos->leaf_weight;
1386
1387 while (propagate) {
1388 struct cfq_group *parent = cfqg_parent(pos);
1389
1390 /* @pos has 0 nr_active at this point */
1391 WARN_ON_ONCE(pos->children_weight);
1392 pos->vfraction = 0;
1393
1394 if (!parent)
1395 break;
1396
1397 propagate = !--parent->nr_active;
1398 parent->children_weight -= pos->weight;
1399 pos = parent;
1400 }
1401
1402 /* remove from the service tree */
1403 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1404 cfq_rb_erase(&cfqg->rb_node, st);
1405}
1406
1407static void
1408cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1409{
1410 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1411
1412 BUG_ON(cfqg->nr_cfqq < 1);
1413 cfqg->nr_cfqq--;
1414
1415 /* If there are other cfq queues under this group, don't delete it */
1416 if (cfqg->nr_cfqq)
1417 return;
1418
1419 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1420 cfq_group_service_tree_del(st, cfqg);
1421 cfqg->saved_wl_slice = 0;
1422 cfqg_stats_update_dequeue(cfqg);
1423}
1424
1425static inline u64 cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1426 u64 *unaccounted_time)
1427{
1428 u64 slice_used;
1429 u64 now = ktime_get_ns();
1430
1431 /*
1432 * Queue got expired before even a single request completed or
1433 * got expired immediately after first request completion.
1434 */
1435 if (!cfqq->slice_start || cfqq->slice_start == now) {
1436 /*
1437 * Also charge the seek time incurred to the group, otherwise
1438 * if there are mutiple queues in the group, each can dispatch
1439 * a single request on seeky media and cause lots of seek time
1440 * and group will never know it.
1441 */
1442 slice_used = max_t(u64, (now - cfqq->dispatch_start),
1443 jiffies_to_nsecs(1));
1444 } else {
1445 slice_used = now - cfqq->slice_start;
1446 if (slice_used > cfqq->allocated_slice) {
1447 *unaccounted_time = slice_used - cfqq->allocated_slice;
1448 slice_used = cfqq->allocated_slice;
1449 }
1450 if (cfqq->slice_start > cfqq->dispatch_start)
1451 *unaccounted_time += cfqq->slice_start -
1452 cfqq->dispatch_start;
1453 }
1454
1455 return slice_used;
1456}
1457
1458static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1459 struct cfq_queue *cfqq)
1460{
1461 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1462 u64 used_sl, charge, unaccounted_sl = 0;
1463 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1464 - cfqg->service_tree_idle.count;
1465 unsigned int vfr;
1466 u64 now = ktime_get_ns();
1467
1468 BUG_ON(nr_sync < 0);
1469 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1470
1471 if (iops_mode(cfqd))
1472 charge = cfqq->slice_dispatch;
1473 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1474 charge = cfqq->allocated_slice;
1475
1476 /*
1477 * Can't update vdisktime while on service tree and cfqg->vfraction
1478 * is valid only while on it. Cache vfr, leave the service tree,
1479 * update vdisktime and go back on. The re-addition to the tree
1480 * will also update the weights as necessary.
1481 */
1482 vfr = cfqg->vfraction;
1483 cfq_group_service_tree_del(st, cfqg);
1484 cfqg->vdisktime += cfqg_scale_charge(charge, vfr);
1485 cfq_group_service_tree_add(st, cfqg);
1486
1487 /* This group is being expired. Save the context */
1488 if (cfqd->workload_expires > now) {
1489 cfqg->saved_wl_slice = cfqd->workload_expires - now;
1490 cfqg->saved_wl_type = cfqd->serving_wl_type;
1491 cfqg->saved_wl_class = cfqd->serving_wl_class;
1492 } else
1493 cfqg->saved_wl_slice = 0;
1494
1495 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1496 st->min_vdisktime);
1497 cfq_log_cfqq(cfqq->cfqd, cfqq,
1498 "sl_used=%llu disp=%llu charge=%llu iops=%u sect=%lu",
1499 used_sl, cfqq->slice_dispatch, charge,
1500 iops_mode(cfqd), cfqq->nr_sectors);
1501 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1502 cfqg_stats_set_start_empty_time(cfqg);
1503}
1504
1505/**
1506 * cfq_init_cfqg_base - initialize base part of a cfq_group
1507 * @cfqg: cfq_group to initialize
1508 *
1509 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1510 * is enabled or not.
1511 */
1512static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1513{
1514 struct cfq_rb_root *st;
1515 int i, j;
1516
1517 for_each_cfqg_st(cfqg, i, j, st)
1518 *st = CFQ_RB_ROOT;
1519 RB_CLEAR_NODE(&cfqg->rb_node);
1520
1521 cfqg->ttime.last_end_request = ktime_get_ns();
1522}
1523
1524#ifdef CONFIG_CFQ_GROUP_IOSCHED
1525static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
1526 bool on_dfl, bool reset_dev, bool is_leaf_weight);
1527
1528static void cfqg_stats_exit(struct cfqg_stats *stats)
1529{
1530 blkg_rwstat_exit(&stats->merged);
1531 blkg_rwstat_exit(&stats->service_time);
1532 blkg_rwstat_exit(&stats->wait_time);
1533 blkg_rwstat_exit(&stats->queued);
1534 blkg_stat_exit(&stats->time);
1535#ifdef CONFIG_DEBUG_BLK_CGROUP
1536 blkg_stat_exit(&stats->unaccounted_time);
1537 blkg_stat_exit(&stats->avg_queue_size_sum);
1538 blkg_stat_exit(&stats->avg_queue_size_samples);
1539 blkg_stat_exit(&stats->dequeue);
1540 blkg_stat_exit(&stats->group_wait_time);
1541 blkg_stat_exit(&stats->idle_time);
1542 blkg_stat_exit(&stats->empty_time);
1543#endif
1544}
1545
1546static int cfqg_stats_init(struct cfqg_stats *stats, gfp_t gfp)
1547{
1548 if (blkg_rwstat_init(&stats->merged, gfp) ||
1549 blkg_rwstat_init(&stats->service_time, gfp) ||
1550 blkg_rwstat_init(&stats->wait_time, gfp) ||
1551 blkg_rwstat_init(&stats->queued, gfp) ||
1552 blkg_stat_init(&stats->time, gfp))
1553 goto err;
1554
1555#ifdef CONFIG_DEBUG_BLK_CGROUP
1556 if (blkg_stat_init(&stats->unaccounted_time, gfp) ||
1557 blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
1558 blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
1559 blkg_stat_init(&stats->dequeue, gfp) ||
1560 blkg_stat_init(&stats->group_wait_time, gfp) ||
1561 blkg_stat_init(&stats->idle_time, gfp) ||
1562 blkg_stat_init(&stats->empty_time, gfp))
1563 goto err;
1564#endif
1565 return 0;
1566err:
1567 cfqg_stats_exit(stats);
1568 return -ENOMEM;
1569}
1570
1571static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp)
1572{
1573 struct cfq_group_data *cgd;
1574
1575 cgd = kzalloc(sizeof(*cgd), gfp);
1576 if (!cgd)
1577 return NULL;
1578 return &cgd->cpd;
1579}
1580
1581static void cfq_cpd_init(struct blkcg_policy_data *cpd)
1582{
1583 struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);
1584 unsigned int weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
1585 CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
1586
1587 if (cpd_to_blkcg(cpd) == &blkcg_root)
1588 weight *= 2;
1589
1590 cgd->weight = weight;
1591 cgd->leaf_weight = weight;
1592}
1593
1594static void cfq_cpd_free(struct blkcg_policy_data *cpd)
1595{
1596 kfree(cpd_to_cfqgd(cpd));
1597}
1598
1599static void cfq_cpd_bind(struct blkcg_policy_data *cpd)
1600{
1601 struct blkcg *blkcg = cpd_to_blkcg(cpd);
1602 bool on_dfl = cgroup_subsys_on_dfl(io_cgrp_subsys);
1603 unsigned int weight = on_dfl ? CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
1604
1605 if (blkcg == &blkcg_root)
1606 weight *= 2;
1607
1608 WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, false));
1609 WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, true));
1610}
1611
1612static struct blkg_policy_data *cfq_pd_alloc(gfp_t gfp, int node)
1613{
1614 struct cfq_group *cfqg;
1615
1616 cfqg = kzalloc_node(sizeof(*cfqg), gfp, node);
1617 if (!cfqg)
1618 return NULL;
1619
1620 cfq_init_cfqg_base(cfqg);
1621 if (cfqg_stats_init(&cfqg->stats, gfp)) {
1622 kfree(cfqg);
1623 return NULL;
1624 }
1625
1626 return &cfqg->pd;
1627}
1628
1629static void cfq_pd_init(struct blkg_policy_data *pd)
1630{
1631 struct cfq_group *cfqg = pd_to_cfqg(pd);
1632 struct cfq_group_data *cgd = blkcg_to_cfqgd(pd->blkg->blkcg);
1633
1634 cfqg->weight = cgd->weight;
1635 cfqg->leaf_weight = cgd->leaf_weight;
1636}
1637
1638static void cfq_pd_offline(struct blkg_policy_data *pd)
1639{
1640 struct cfq_group *cfqg = pd_to_cfqg(pd);
1641 int i;
1642
1643 for (i = 0; i < IOPRIO_BE_NR; i++) {
1644 if (cfqg->async_cfqq[0][i])
1645 cfq_put_queue(cfqg->async_cfqq[0][i]);
1646 if (cfqg->async_cfqq[1][i])
1647 cfq_put_queue(cfqg->async_cfqq[1][i]);
1648 }
1649
1650 if (cfqg->async_idle_cfqq)
1651 cfq_put_queue(cfqg->async_idle_cfqq);
1652
1653 /*
1654 * @blkg is going offline and will be ignored by
1655 * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
1656 * that they don't get lost. If IOs complete after this point, the
1657 * stats for them will be lost. Oh well...
1658 */
1659 cfqg_stats_xfer_dead(cfqg);
1660}
1661
1662static void cfq_pd_free(struct blkg_policy_data *pd)
1663{
1664 struct cfq_group *cfqg = pd_to_cfqg(pd);
1665
1666 cfqg_stats_exit(&cfqg->stats);
1667 return kfree(cfqg);
1668}
1669
1670static void cfq_pd_reset_stats(struct blkg_policy_data *pd)
1671{
1672 struct cfq_group *cfqg = pd_to_cfqg(pd);
1673
1674 cfqg_stats_reset(&cfqg->stats);
1675}
1676
1677static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
1678 struct blkcg *blkcg)
1679{
1680 struct blkcg_gq *blkg;
1681
1682 blkg = blkg_lookup(blkcg, cfqd->queue);
1683 if (likely(blkg))
1684 return blkg_to_cfqg(blkg);
1685 return NULL;
1686}
1687
1688static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1689{
1690 cfqq->cfqg = cfqg;
1691 /* cfqq reference on cfqg */
1692 cfqg_get(cfqg);
1693}
1694
1695static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1696 struct blkg_policy_data *pd, int off)
1697{
1698 struct cfq_group *cfqg = pd_to_cfqg(pd);
1699
1700 if (!cfqg->dev_weight)
1701 return 0;
1702 return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1703}
1704
1705static int cfqg_print_weight_device(struct seq_file *sf, void *v)
1706{
1707 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1708 cfqg_prfill_weight_device, &blkcg_policy_cfq,
1709 0, false);
1710 return 0;
1711}
1712
1713static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf,
1714 struct blkg_policy_data *pd, int off)
1715{
1716 struct cfq_group *cfqg = pd_to_cfqg(pd);
1717
1718 if (!cfqg->dev_leaf_weight)
1719 return 0;
1720 return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight);
1721}
1722
1723static int cfqg_print_leaf_weight_device(struct seq_file *sf, void *v)
1724{
1725 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1726 cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq,
1727 0, false);
1728 return 0;
1729}
1730
1731static int cfq_print_weight(struct seq_file *sf, void *v)
1732{
1733 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1734 struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1735 unsigned int val = 0;
1736
1737 if (cgd)
1738 val = cgd->weight;
1739
1740 seq_printf(sf, "%u\n", val);
1741 return 0;
1742}
1743
1744static int cfq_print_leaf_weight(struct seq_file *sf, void *v)
1745{
1746 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1747 struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1748 unsigned int val = 0;
1749
1750 if (cgd)
1751 val = cgd->leaf_weight;
1752
1753 seq_printf(sf, "%u\n", val);
1754 return 0;
1755}
1756
1757static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
1758 char *buf, size_t nbytes, loff_t off,
1759 bool on_dfl, bool is_leaf_weight)
1760{
1761 unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
1762 unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
1763 struct blkcg *blkcg = css_to_blkcg(of_css(of));
1764 struct blkg_conf_ctx ctx;
1765 struct cfq_group *cfqg;
1766 struct cfq_group_data *cfqgd;
1767 int ret;
1768 u64 v;
1769
1770 ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1771 if (ret)
1772 return ret;
1773
1774 if (sscanf(ctx.body, "%llu", &v) == 1) {
1775 /* require "default" on dfl */
1776 ret = -ERANGE;
1777 if (!v && on_dfl)
1778 goto out_finish;
1779 } else if (!strcmp(strim(ctx.body), "default")) {
1780 v = 0;
1781 } else {
1782 ret = -EINVAL;
1783 goto out_finish;
1784 }
1785
1786 cfqg = blkg_to_cfqg(ctx.blkg);
1787 cfqgd = blkcg_to_cfqgd(blkcg);
1788
1789 ret = -ERANGE;
1790 if (!v || (v >= min && v <= max)) {
1791 if (!is_leaf_weight) {
1792 cfqg->dev_weight = v;
1793 cfqg->new_weight = v ?: cfqgd->weight;
1794 } else {
1795 cfqg->dev_leaf_weight = v;
1796 cfqg->new_leaf_weight = v ?: cfqgd->leaf_weight;
1797 }
1798 ret = 0;
1799 }
1800out_finish:
1801 blkg_conf_finish(&ctx);
1802 return ret ?: nbytes;
1803}
1804
1805static ssize_t cfqg_set_weight_device(struct kernfs_open_file *of,
1806 char *buf, size_t nbytes, loff_t off)
1807{
1808 return __cfqg_set_weight_device(of, buf, nbytes, off, false, false);
1809}
1810
1811static ssize_t cfqg_set_leaf_weight_device(struct kernfs_open_file *of,
1812 char *buf, size_t nbytes, loff_t off)
1813{
1814 return __cfqg_set_weight_device(of, buf, nbytes, off, false, true);
1815}
1816
1817static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
1818 bool on_dfl, bool reset_dev, bool is_leaf_weight)
1819{
1820 unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
1821 unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
1822 struct blkcg *blkcg = css_to_blkcg(css);
1823 struct blkcg_gq *blkg;
1824 struct cfq_group_data *cfqgd;
1825 int ret = 0;
1826
1827 if (val < min || val > max)
1828 return -ERANGE;
1829
1830 spin_lock_irq(&blkcg->lock);
1831 cfqgd = blkcg_to_cfqgd(blkcg);
1832 if (!cfqgd) {
1833 ret = -EINVAL;
1834 goto out;
1835 }
1836
1837 if (!is_leaf_weight)
1838 cfqgd->weight = val;
1839 else
1840 cfqgd->leaf_weight = val;
1841
1842 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
1843 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1844
1845 if (!cfqg)
1846 continue;
1847
1848 if (!is_leaf_weight) {
1849 if (reset_dev)
1850 cfqg->dev_weight = 0;
1851 if (!cfqg->dev_weight)
1852 cfqg->new_weight = cfqgd->weight;
1853 } else {
1854 if (reset_dev)
1855 cfqg->dev_leaf_weight = 0;
1856 if (!cfqg->dev_leaf_weight)
1857 cfqg->new_leaf_weight = cfqgd->leaf_weight;
1858 }
1859 }
1860
1861out:
1862 spin_unlock_irq(&blkcg->lock);
1863 return ret;
1864}
1865
1866static int cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1867 u64 val)
1868{
1869 return __cfq_set_weight(css, val, false, false, false);
1870}
1871
1872static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,
1873 struct cftype *cft, u64 val)
1874{
1875 return __cfq_set_weight(css, val, false, false, true);
1876}
1877
1878static int cfqg_print_stat(struct seq_file *sf, void *v)
1879{
1880 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
1881 &blkcg_policy_cfq, seq_cft(sf)->private, false);
1882 return 0;
1883}
1884
1885static int cfqg_print_rwstat(struct seq_file *sf, void *v)
1886{
1887 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
1888 &blkcg_policy_cfq, seq_cft(sf)->private, true);
1889 return 0;
1890}
1891
1892static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
1893 struct blkg_policy_data *pd, int off)
1894{
1895 u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
1896 &blkcg_policy_cfq, off);
1897 return __blkg_prfill_u64(sf, pd, sum);
1898}
1899
1900static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
1901 struct blkg_policy_data *pd, int off)
1902{
1903 struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
1904 &blkcg_policy_cfq, off);
1905 return __blkg_prfill_rwstat(sf, pd, &sum);
1906}
1907
1908static int cfqg_print_stat_recursive(struct seq_file *sf, void *v)
1909{
1910 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1911 cfqg_prfill_stat_recursive, &blkcg_policy_cfq,
1912 seq_cft(sf)->private, false);
1913 return 0;
1914}
1915
1916static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
1917{
1918 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1919 cfqg_prfill_rwstat_recursive, &blkcg_policy_cfq,
1920 seq_cft(sf)->private, true);
1921 return 0;
1922}
1923
1924static u64 cfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
1925 int off)
1926{
1927 u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
1928
1929 return __blkg_prfill_u64(sf, pd, sum >> 9);
1930}
1931
1932static int cfqg_print_stat_sectors(struct seq_file *sf, void *v)
1933{
1934 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1935 cfqg_prfill_sectors, &blkcg_policy_cfq, 0, false);
1936 return 0;
1937}
1938
1939static u64 cfqg_prfill_sectors_recursive(struct seq_file *sf,
1940 struct blkg_policy_data *pd, int off)
1941{
1942 struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
1943 offsetof(struct blkcg_gq, stat_bytes));
1944 u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
1945 atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
1946
1947 return __blkg_prfill_u64(sf, pd, sum >> 9);
1948}
1949
1950static int cfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
1951{
1952 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1953 cfqg_prfill_sectors_recursive, &blkcg_policy_cfq, 0,
1954 false);
1955 return 0;
1956}
1957
1958#ifdef CONFIG_DEBUG_BLK_CGROUP
1959static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1960 struct blkg_policy_data *pd, int off)
1961{
1962 struct cfq_group *cfqg = pd_to_cfqg(pd);
1963 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1964 u64 v = 0;
1965
1966 if (samples) {
1967 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1968 v = div64_u64(v, samples);
1969 }
1970 __blkg_prfill_u64(sf, pd, v);
1971 return 0;
1972}
1973
1974/* print avg_queue_size */
1975static int cfqg_print_avg_queue_size(struct seq_file *sf, void *v)
1976{
1977 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1978 cfqg_prfill_avg_queue_size, &blkcg_policy_cfq,
1979 0, false);
1980 return 0;
1981}
1982#endif /* CONFIG_DEBUG_BLK_CGROUP */
1983
1984static struct cftype cfq_blkcg_legacy_files[] = {
1985 /* on root, weight is mapped to leaf_weight */
1986 {
1987 .name = "weight_device",
1988 .flags = CFTYPE_ONLY_ON_ROOT,
1989 .seq_show = cfqg_print_leaf_weight_device,
1990 .write = cfqg_set_leaf_weight_device,
1991 },
1992 {
1993 .name = "weight",
1994 .flags = CFTYPE_ONLY_ON_ROOT,
1995 .seq_show = cfq_print_leaf_weight,
1996 .write_u64 = cfq_set_leaf_weight,
1997 },
1998
1999 /* no such mapping necessary for !roots */
2000 {
2001 .name = "weight_device",
2002 .flags = CFTYPE_NOT_ON_ROOT,
2003 .seq_show = cfqg_print_weight_device,
2004 .write = cfqg_set_weight_device,
2005 },
2006 {
2007 .name = "weight",
2008 .flags = CFTYPE_NOT_ON_ROOT,
2009 .seq_show = cfq_print_weight,
2010 .write_u64 = cfq_set_weight,
2011 },
2012
2013 {
2014 .name = "leaf_weight_device",
2015 .seq_show = cfqg_print_leaf_weight_device,
2016 .write = cfqg_set_leaf_weight_device,
2017 },
2018 {
2019 .name = "leaf_weight",
2020 .seq_show = cfq_print_leaf_weight,
2021 .write_u64 = cfq_set_leaf_weight,
2022 },
2023
2024 /* statistics, covers only the tasks in the cfqg */
2025 {
2026 .name = "time",
2027 .private = offsetof(struct cfq_group, stats.time),
2028 .seq_show = cfqg_print_stat,
2029 },
2030 {
2031 .name = "sectors",
2032 .seq_show = cfqg_print_stat_sectors,
2033 },
2034 {
2035 .name = "io_service_bytes",
2036 .private = (unsigned long)&blkcg_policy_cfq,
2037 .seq_show = blkg_print_stat_bytes,
2038 },
2039 {
2040 .name = "io_serviced",
2041 .private = (unsigned long)&blkcg_policy_cfq,
2042 .seq_show = blkg_print_stat_ios,
2043 },
2044 {
2045 .name = "io_service_time",
2046 .private = offsetof(struct cfq_group, stats.service_time),
2047 .seq_show = cfqg_print_rwstat,
2048 },
2049 {
2050 .name = "io_wait_time",
2051 .private = offsetof(struct cfq_group, stats.wait_time),
2052 .seq_show = cfqg_print_rwstat,
2053 },
2054 {
2055 .name = "io_merged",
2056 .private = offsetof(struct cfq_group, stats.merged),
2057 .seq_show = cfqg_print_rwstat,
2058 },
2059 {
2060 .name = "io_queued",
2061 .private = offsetof(struct cfq_group, stats.queued),
2062 .seq_show = cfqg_print_rwstat,
2063 },
2064
2065 /* the same statictics which cover the cfqg and its descendants */
2066 {
2067 .name = "time_recursive",
2068 .private = offsetof(struct cfq_group, stats.time),
2069 .seq_show = cfqg_print_stat_recursive,
2070 },
2071 {
2072 .name = "sectors_recursive",
2073 .seq_show = cfqg_print_stat_sectors_recursive,
2074 },
2075 {
2076 .name = "io_service_bytes_recursive",
2077 .private = (unsigned long)&blkcg_policy_cfq,
2078 .seq_show = blkg_print_stat_bytes_recursive,
2079 },
2080 {
2081 .name = "io_serviced_recursive",
2082 .private = (unsigned long)&blkcg_policy_cfq,
2083 .seq_show = blkg_print_stat_ios_recursive,
2084 },
2085 {
2086 .name = "io_service_time_recursive",
2087 .private = offsetof(struct cfq_group, stats.service_time),
2088 .seq_show = cfqg_print_rwstat_recursive,
2089 },
2090 {
2091 .name = "io_wait_time_recursive",
2092 .private = offsetof(struct cfq_group, stats.wait_time),
2093 .seq_show = cfqg_print_rwstat_recursive,
2094 },
2095 {
2096 .name = "io_merged_recursive",
2097 .private = offsetof(struct cfq_group, stats.merged),
2098 .seq_show = cfqg_print_rwstat_recursive,
2099 },
2100 {
2101 .name = "io_queued_recursive",
2102 .private = offsetof(struct cfq_group, stats.queued),
2103 .seq_show = cfqg_print_rwstat_recursive,
2104 },
2105#ifdef CONFIG_DEBUG_BLK_CGROUP
2106 {
2107 .name = "avg_queue_size",
2108 .seq_show = cfqg_print_avg_queue_size,
2109 },
2110 {
2111 .name = "group_wait_time",
2112 .private = offsetof(struct cfq_group, stats.group_wait_time),
2113 .seq_show = cfqg_print_stat,
2114 },
2115 {
2116 .name = "idle_time",
2117 .private = offsetof(struct cfq_group, stats.idle_time),
2118 .seq_show = cfqg_print_stat,
2119 },
2120 {
2121 .name = "empty_time",
2122 .private = offsetof(struct cfq_group, stats.empty_time),
2123 .seq_show = cfqg_print_stat,
2124 },
2125 {
2126 .name = "dequeue",
2127 .private = offsetof(struct cfq_group, stats.dequeue),
2128 .seq_show = cfqg_print_stat,
2129 },
2130 {
2131 .name = "unaccounted_time",
2132 .private = offsetof(struct cfq_group, stats.unaccounted_time),
2133 .seq_show = cfqg_print_stat,
2134 },
2135#endif /* CONFIG_DEBUG_BLK_CGROUP */
2136 { } /* terminate */
2137};
2138
2139static int cfq_print_weight_on_dfl(struct seq_file *sf, void *v)
2140{
2141 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
2142 struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
2143
2144 seq_printf(sf, "default %u\n", cgd->weight);
2145 blkcg_print_blkgs(sf, blkcg, cfqg_prfill_weight_device,
2146 &blkcg_policy_cfq, 0, false);
2147 return 0;
2148}
2149
2150static ssize_t cfq_set_weight_on_dfl(struct kernfs_open_file *of,
2151 char *buf, size_t nbytes, loff_t off)
2152{
2153 char *endp;
2154 int ret;
2155 u64 v;
2156
2157 buf = strim(buf);
2158
2159 /* "WEIGHT" or "default WEIGHT" sets the default weight */
2160 v = simple_strtoull(buf, &endp, 0);
2161 if (*endp == '\0' || sscanf(buf, "default %llu", &v) == 1) {
2162 ret = __cfq_set_weight(of_css(of), v, true, false, false);
2163 return ret ?: nbytes;
2164 }
2165
2166 /* "MAJ:MIN WEIGHT" */
2167 return __cfqg_set_weight_device(of, buf, nbytes, off, true, false);
2168}
2169
2170static struct cftype cfq_blkcg_files[] = {
2171 {
2172 .name = "weight",
2173 .flags = CFTYPE_NOT_ON_ROOT,
2174 .seq_show = cfq_print_weight_on_dfl,
2175 .write = cfq_set_weight_on_dfl,
2176 },
2177 { } /* terminate */
2178};
2179
2180#else /* GROUP_IOSCHED */
2181static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
2182 struct blkcg *blkcg)
2183{
2184 return cfqd->root_group;
2185}
2186
2187static inline void
2188cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
2189 cfqq->cfqg = cfqg;
2190}
2191
2192#endif /* GROUP_IOSCHED */
2193
2194/*
2195 * The cfqd->service_trees holds all pending cfq_queue's that have
2196 * requests waiting to be processed. It is sorted in the order that
2197 * we will service the queues.
2198 */
2199static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2200 bool add_front)
2201{
2202 struct rb_node **p, *parent;
2203 struct cfq_queue *__cfqq;
2204 u64 rb_key;
2205 struct cfq_rb_root *st;
2206 bool leftmost = true;
2207 int new_cfqq = 1;
2208 u64 now = ktime_get_ns();
2209
2210 st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
2211 if (cfq_class_idle(cfqq)) {
2212 rb_key = CFQ_IDLE_DELAY;
2213 parent = st->rb_rightmost;
2214 if (parent && parent != &cfqq->rb_node) {
2215 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2216 rb_key += __cfqq->rb_key;
2217 } else
2218 rb_key += now;
2219 } else if (!add_front) {
2220 /*
2221 * Get our rb key offset. Subtract any residual slice
2222 * value carried from last service. A negative resid
2223 * count indicates slice overrun, and this should position
2224 * the next service time further away in the tree.
2225 */
2226 rb_key = cfq_slice_offset(cfqd, cfqq) + now;
2227 rb_key -= cfqq->slice_resid;
2228 cfqq->slice_resid = 0;
2229 } else {
2230 rb_key = -NSEC_PER_SEC;
2231 __cfqq = cfq_rb_first(st);
2232 rb_key += __cfqq ? __cfqq->rb_key : now;
2233 }
2234
2235 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2236 new_cfqq = 0;
2237 /*
2238 * same position, nothing more to do
2239 */
2240 if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
2241 return;
2242
2243 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2244 cfqq->service_tree = NULL;
2245 }
2246
2247 parent = NULL;
2248 cfqq->service_tree = st;
2249 p = &st->rb.rb_root.rb_node;
2250 while (*p) {
2251 parent = *p;
2252 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2253
2254 /*
2255 * sort by key, that represents service time.
2256 */
2257 if (rb_key < __cfqq->rb_key)
2258 p = &parent->rb_left;
2259 else {
2260 p = &parent->rb_right;
2261 leftmost = false;
2262 }
2263 }
2264
2265 cfqq->rb_key = rb_key;
2266 rb_link_node(&cfqq->rb_node, parent, p);
2267 rb_insert_color_cached(&cfqq->rb_node, &st->rb, leftmost);
2268 st->count++;
2269 if (add_front || !new_cfqq)
2270 return;
2271 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
2272}
2273
2274static struct cfq_queue *
2275cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
2276 sector_t sector, struct rb_node **ret_parent,
2277 struct rb_node ***rb_link)
2278{
2279 struct rb_node **p, *parent;
2280 struct cfq_queue *cfqq = NULL;
2281
2282 parent = NULL;
2283 p = &root->rb_node;
2284 while (*p) {
2285 struct rb_node **n;
2286
2287 parent = *p;
2288 cfqq = rb_entry(parent, struct cfq_queue, p_node);
2289
2290 /*
2291 * Sort strictly based on sector. Smallest to the left,
2292 * largest to the right.
2293 */
2294 if (sector > blk_rq_pos(cfqq->next_rq))
2295 n = &(*p)->rb_right;
2296 else if (sector < blk_rq_pos(cfqq->next_rq))
2297 n = &(*p)->rb_left;
2298 else
2299 break;
2300 p = n;
2301 cfqq = NULL;
2302 }
2303
2304 *ret_parent = parent;
2305 if (rb_link)
2306 *rb_link = p;
2307 return cfqq;
2308}
2309
2310static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2311{
2312 struct rb_node **p, *parent;
2313 struct cfq_queue *__cfqq;
2314
2315 if (cfqq->p_root) {
2316 rb_erase(&cfqq->p_node, cfqq->p_root);
2317 cfqq->p_root = NULL;
2318 }
2319
2320 if (cfq_class_idle(cfqq))
2321 return;
2322 if (!cfqq->next_rq)
2323 return;
2324
2325 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
2326 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
2327 blk_rq_pos(cfqq->next_rq), &parent, &p);
2328 if (!__cfqq) {
2329 rb_link_node(&cfqq->p_node, parent, p);
2330 rb_insert_color(&cfqq->p_node, cfqq->p_root);
2331 } else
2332 cfqq->p_root = NULL;
2333}
2334
2335/*
2336 * Update cfqq's position in the service tree.
2337 */
2338static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2339{
2340 /*
2341 * Resorting requires the cfqq to be on the RR list already.
2342 */
2343 if (cfq_cfqq_on_rr(cfqq)) {
2344 cfq_service_tree_add(cfqd, cfqq, 0);
2345 cfq_prio_tree_add(cfqd, cfqq);
2346 }
2347}
2348
2349/*
2350 * add to busy list of queues for service, trying to be fair in ordering
2351 * the pending list according to last request service
2352 */
2353static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2354{
2355 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
2356 BUG_ON(cfq_cfqq_on_rr(cfqq));
2357 cfq_mark_cfqq_on_rr(cfqq);
2358 cfqd->busy_queues++;
2359 if (cfq_cfqq_sync(cfqq))
2360 cfqd->busy_sync_queues++;
2361
2362 cfq_resort_rr_list(cfqd, cfqq);
2363}
2364
2365/*
2366 * Called when the cfqq no longer has requests pending, remove it from
2367 * the service tree.
2368 */
2369static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2370{
2371 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
2372 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2373 cfq_clear_cfqq_on_rr(cfqq);
2374
2375 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2376 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2377 cfqq->service_tree = NULL;
2378 }
2379 if (cfqq->p_root) {
2380 rb_erase(&cfqq->p_node, cfqq->p_root);
2381 cfqq->p_root = NULL;
2382 }
2383
2384 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
2385 BUG_ON(!cfqd->busy_queues);
2386 cfqd->busy_queues--;
2387 if (cfq_cfqq_sync(cfqq))
2388 cfqd->busy_sync_queues--;
2389}
2390
2391/*
2392 * rb tree support functions
2393 */
2394static void cfq_del_rq_rb(struct request *rq)
2395{
2396 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2397 const int sync = rq_is_sync(rq);
2398
2399 BUG_ON(!cfqq->queued[sync]);
2400 cfqq->queued[sync]--;
2401
2402 elv_rb_del(&cfqq->sort_list, rq);
2403
2404 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
2405 /*
2406 * Queue will be deleted from service tree when we actually
2407 * expire it later. Right now just remove it from prio tree
2408 * as it is empty.
2409 */
2410 if (cfqq->p_root) {
2411 rb_erase(&cfqq->p_node, cfqq->p_root);
2412 cfqq->p_root = NULL;
2413 }
2414 }
2415}
2416
2417static void cfq_add_rq_rb(struct request *rq)
2418{
2419 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2420 struct cfq_data *cfqd = cfqq->cfqd;
2421 struct request *prev;
2422
2423 cfqq->queued[rq_is_sync(rq)]++;
2424
2425 elv_rb_add(&cfqq->sort_list, rq);
2426
2427 if (!cfq_cfqq_on_rr(cfqq))
2428 cfq_add_cfqq_rr(cfqd, cfqq);
2429
2430 /*
2431 * check if this request is a better next-serve candidate
2432 */
2433 prev = cfqq->next_rq;
2434 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
2435
2436 /*
2437 * adjust priority tree position, if ->next_rq changes
2438 */
2439 if (prev != cfqq->next_rq)
2440 cfq_prio_tree_add(cfqd, cfqq);
2441
2442 BUG_ON(!cfqq->next_rq);
2443}
2444
2445static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
2446{
2447 elv_rb_del(&cfqq->sort_list, rq);
2448 cfqq->queued[rq_is_sync(rq)]--;
2449 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2450 cfq_add_rq_rb(rq);
2451 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
2452 rq->cmd_flags);
2453}
2454
2455static struct request *
2456cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
2457{
2458 struct task_struct *tsk = current;
2459 struct cfq_io_cq *cic;
2460 struct cfq_queue *cfqq;
2461
2462 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2463 if (!cic)
2464 return NULL;
2465
2466 cfqq = cic_to_cfqq(cic, op_is_sync(bio->bi_opf));
2467 if (cfqq)
2468 return elv_rb_find(&cfqq->sort_list, bio_end_sector(bio));
2469
2470 return NULL;
2471}
2472
2473static void cfq_activate_request(struct request_queue *q, struct request *rq)
2474{
2475 struct cfq_data *cfqd = q->elevator->elevator_data;
2476
2477 cfqd->rq_in_driver++;
2478 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
2479 cfqd->rq_in_driver);
2480
2481 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
2482}
2483
2484static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
2485{
2486 struct cfq_data *cfqd = q->elevator->elevator_data;
2487
2488 WARN_ON(!cfqd->rq_in_driver);
2489 cfqd->rq_in_driver--;
2490 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
2491 cfqd->rq_in_driver);
2492}
2493
2494static void cfq_remove_request(struct request *rq)
2495{
2496 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2497
2498 if (cfqq->next_rq == rq)
2499 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
2500
2501 list_del_init(&rq->queuelist);
2502 cfq_del_rq_rb(rq);
2503
2504 cfqq->cfqd->rq_queued--;
2505 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2506 if (rq->cmd_flags & REQ_PRIO) {
2507 WARN_ON(!cfqq->prio_pending);
2508 cfqq->prio_pending--;
2509 }
2510}
2511
2512static enum elv_merge cfq_merge(struct request_queue *q, struct request **req,
2513 struct bio *bio)
2514{
2515 struct cfq_data *cfqd = q->elevator->elevator_data;
2516 struct request *__rq;
2517
2518 __rq = cfq_find_rq_fmerge(cfqd, bio);
2519 if (__rq && elv_bio_merge_ok(__rq, bio)) {
2520 *req = __rq;
2521 return ELEVATOR_FRONT_MERGE;
2522 }
2523
2524 return ELEVATOR_NO_MERGE;
2525}
2526
2527static void cfq_merged_request(struct request_queue *q, struct request *req,
2528 enum elv_merge type)
2529{
2530 if (type == ELEVATOR_FRONT_MERGE) {
2531 struct cfq_queue *cfqq = RQ_CFQQ(req);
2532
2533 cfq_reposition_rq_rb(cfqq, req);
2534 }
2535}
2536
2537static void cfq_bio_merged(struct request_queue *q, struct request *req,
2538 struct bio *bio)
2539{
2540 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_opf);
2541}
2542
2543static void
2544cfq_merged_requests(struct request_queue *q, struct request *rq,
2545 struct request *next)
2546{
2547 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2548 struct cfq_data *cfqd = q->elevator->elevator_data;
2549
2550 /*
2551 * reposition in fifo if next is older than rq
2552 */
2553 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
2554 next->fifo_time < rq->fifo_time &&
2555 cfqq == RQ_CFQQ(next)) {
2556 list_move(&rq->queuelist, &next->queuelist);
2557 rq->fifo_time = next->fifo_time;
2558 }
2559
2560 if (cfqq->next_rq == next)
2561 cfqq->next_rq = rq;
2562 cfq_remove_request(next);
2563 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
2564
2565 cfqq = RQ_CFQQ(next);
2566 /*
2567 * all requests of this queue are merged to other queues, delete it
2568 * from the service tree. If it's the active_queue,
2569 * cfq_dispatch_requests() will choose to expire it or do idle
2570 */
2571 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
2572 cfqq != cfqd->active_queue)
2573 cfq_del_cfqq_rr(cfqd, cfqq);
2574}
2575
2576static int cfq_allow_bio_merge(struct request_queue *q, struct request *rq,
2577 struct bio *bio)
2578{
2579 struct cfq_data *cfqd = q->elevator->elevator_data;
2580 bool is_sync = op_is_sync(bio->bi_opf);
2581 struct cfq_io_cq *cic;
2582 struct cfq_queue *cfqq;
2583
2584 /*
2585 * Disallow merge of a sync bio into an async request.
2586 */
2587 if (is_sync && !rq_is_sync(rq))
2588 return false;
2589
2590 /*
2591 * Lookup the cfqq that this bio will be queued with and allow
2592 * merge only if rq is queued there.
2593 */
2594 cic = cfq_cic_lookup(cfqd, current->io_context);
2595 if (!cic)
2596 return false;
2597
2598 cfqq = cic_to_cfqq(cic, is_sync);
2599 return cfqq == RQ_CFQQ(rq);
2600}
2601
2602static int cfq_allow_rq_merge(struct request_queue *q, struct request *rq,
2603 struct request *next)
2604{
2605 return RQ_CFQQ(rq) == RQ_CFQQ(next);
2606}
2607
2608static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2609{
2610 hrtimer_try_to_cancel(&cfqd->idle_slice_timer);
2611 cfqg_stats_update_idle_time(cfqq->cfqg);
2612}
2613
2614static void __cfq_set_active_queue(struct cfq_data *cfqd,
2615 struct cfq_queue *cfqq)
2616{
2617 if (cfqq) {
2618 cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
2619 cfqd->serving_wl_class, cfqd->serving_wl_type);
2620 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2621 cfqq->slice_start = 0;
2622 cfqq->dispatch_start = ktime_get_ns();
2623 cfqq->allocated_slice = 0;
2624 cfqq->slice_end = 0;
2625 cfqq->slice_dispatch = 0;
2626 cfqq->nr_sectors = 0;
2627
2628 cfq_clear_cfqq_wait_request(cfqq);
2629 cfq_clear_cfqq_must_dispatch(cfqq);
2630 cfq_clear_cfqq_must_alloc_slice(cfqq);
2631 cfq_clear_cfqq_fifo_expire(cfqq);
2632 cfq_mark_cfqq_slice_new(cfqq);
2633
2634 cfq_del_timer(cfqd, cfqq);
2635 }
2636
2637 cfqd->active_queue = cfqq;
2638}
2639
2640/*
2641 * current cfqq expired its slice (or was too idle), select new one
2642 */
2643static void
2644__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2645 bool timed_out)
2646{
2647 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2648
2649 if (cfq_cfqq_wait_request(cfqq))
2650 cfq_del_timer(cfqd, cfqq);
2651
2652 cfq_clear_cfqq_wait_request(cfqq);
2653 cfq_clear_cfqq_wait_busy(cfqq);
2654
2655 /*
2656 * If this cfqq is shared between multiple processes, check to
2657 * make sure that those processes are still issuing I/Os within
2658 * the mean seek distance. If not, it may be time to break the
2659 * queues apart again.
2660 */
2661 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2662 cfq_mark_cfqq_split_coop(cfqq);
2663
2664 /*
2665 * store what was left of this slice, if the queue idled/timed out
2666 */
2667 if (timed_out) {
2668 if (cfq_cfqq_slice_new(cfqq))
2669 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2670 else
2671 cfqq->slice_resid = cfqq->slice_end - ktime_get_ns();
2672 cfq_log_cfqq(cfqd, cfqq, "resid=%lld", cfqq->slice_resid);
2673 }
2674
2675 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2676
2677 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2678 cfq_del_cfqq_rr(cfqd, cfqq);
2679
2680 cfq_resort_rr_list(cfqd, cfqq);
2681
2682 if (cfqq == cfqd->active_queue)
2683 cfqd->active_queue = NULL;
2684
2685 if (cfqd->active_cic) {
2686 put_io_context(cfqd->active_cic->icq.ioc);
2687 cfqd->active_cic = NULL;
2688 }
2689}
2690
2691static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2692{
2693 struct cfq_queue *cfqq = cfqd->active_queue;
2694
2695 if (cfqq)
2696 __cfq_slice_expired(cfqd, cfqq, timed_out);
2697}
2698
2699/*
2700 * Get next queue for service. Unless we have a queue preemption,
2701 * we'll simply select the first cfqq in the service tree.
2702 */
2703static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2704{
2705 struct cfq_rb_root *st = st_for(cfqd->serving_group,
2706 cfqd->serving_wl_class, cfqd->serving_wl_type);
2707
2708 if (!cfqd->rq_queued)
2709 return NULL;
2710
2711 /* There is nothing to dispatch */
2712 if (!st)
2713 return NULL;
2714 if (RB_EMPTY_ROOT(&st->rb.rb_root))
2715 return NULL;
2716 return cfq_rb_first(st);
2717}
2718
2719static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2720{
2721 struct cfq_group *cfqg;
2722 struct cfq_queue *cfqq;
2723 int i, j;
2724 struct cfq_rb_root *st;
2725
2726 if (!cfqd->rq_queued)
2727 return NULL;
2728
2729 cfqg = cfq_get_next_cfqg(cfqd);
2730 if (!cfqg)
2731 return NULL;
2732
2733 for_each_cfqg_st(cfqg, i, j, st) {
2734 cfqq = cfq_rb_first(st);
2735 if (cfqq)
2736 return cfqq;
2737 }
2738 return NULL;
2739}
2740
2741/*
2742 * Get and set a new active queue for service.
2743 */
2744static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2745 struct cfq_queue *cfqq)
2746{
2747 if (!cfqq)
2748 cfqq = cfq_get_next_queue(cfqd);
2749
2750 __cfq_set_active_queue(cfqd, cfqq);
2751 return cfqq;
2752}
2753
2754static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2755 struct request *rq)
2756{
2757 if (blk_rq_pos(rq) >= cfqd->last_position)
2758 return blk_rq_pos(rq) - cfqd->last_position;
2759 else
2760 return cfqd->last_position - blk_rq_pos(rq);
2761}
2762
2763static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2764 struct request *rq)
2765{
2766 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2767}
2768
2769static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2770 struct cfq_queue *cur_cfqq)
2771{
2772 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2773 struct rb_node *parent, *node;
2774 struct cfq_queue *__cfqq;
2775 sector_t sector = cfqd->last_position;
2776
2777 if (RB_EMPTY_ROOT(root))
2778 return NULL;
2779
2780 /*
2781 * First, if we find a request starting at the end of the last
2782 * request, choose it.
2783 */
2784 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2785 if (__cfqq)
2786 return __cfqq;
2787
2788 /*
2789 * If the exact sector wasn't found, the parent of the NULL leaf
2790 * will contain the closest sector.
2791 */
2792 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2793 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2794 return __cfqq;
2795
2796 if (blk_rq_pos(__cfqq->next_rq) < sector)
2797 node = rb_next(&__cfqq->p_node);
2798 else
2799 node = rb_prev(&__cfqq->p_node);
2800 if (!node)
2801 return NULL;
2802
2803 __cfqq = rb_entry(node, struct cfq_queue, p_node);
2804 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2805 return __cfqq;
2806
2807 return NULL;
2808}
2809
2810/*
2811 * cfqd - obvious
2812 * cur_cfqq - passed in so that we don't decide that the current queue is
2813 * closely cooperating with itself.
2814 *
2815 * So, basically we're assuming that that cur_cfqq has dispatched at least
2816 * one request, and that cfqd->last_position reflects a position on the disk
2817 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2818 * assumption.
2819 */
2820static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2821 struct cfq_queue *cur_cfqq)
2822{
2823 struct cfq_queue *cfqq;
2824
2825 if (cfq_class_idle(cur_cfqq))
2826 return NULL;
2827 if (!cfq_cfqq_sync(cur_cfqq))
2828 return NULL;
2829 if (CFQQ_SEEKY(cur_cfqq))
2830 return NULL;
2831
2832 /*
2833 * Don't search priority tree if it's the only queue in the group.
2834 */
2835 if (cur_cfqq->cfqg->nr_cfqq == 1)
2836 return NULL;
2837
2838 /*
2839 * We should notice if some of the queues are cooperating, eg
2840 * working closely on the same area of the disk. In that case,
2841 * we can group them together and don't waste time idling.
2842 */
2843 cfqq = cfqq_close(cfqd, cur_cfqq);
2844 if (!cfqq)
2845 return NULL;
2846
2847 /* If new queue belongs to different cfq_group, don't choose it */
2848 if (cur_cfqq->cfqg != cfqq->cfqg)
2849 return NULL;
2850
2851 /*
2852 * It only makes sense to merge sync queues.
2853 */
2854 if (!cfq_cfqq_sync(cfqq))
2855 return NULL;
2856 if (CFQQ_SEEKY(cfqq))
2857 return NULL;
2858
2859 /*
2860 * Do not merge queues of different priority classes
2861 */
2862 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2863 return NULL;
2864
2865 return cfqq;
2866}
2867
2868/*
2869 * Determine whether we should enforce idle window for this queue.
2870 */
2871
2872static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2873{
2874 enum wl_class_t wl_class = cfqq_class(cfqq);
2875 struct cfq_rb_root *st = cfqq->service_tree;
2876
2877 BUG_ON(!st);
2878 BUG_ON(!st->count);
2879
2880 if (!cfqd->cfq_slice_idle)
2881 return false;
2882
2883 /* We never do for idle class queues. */
2884 if (wl_class == IDLE_WORKLOAD)
2885 return false;
2886
2887 /* We do for queues that were marked with idle window flag. */
2888 if (cfq_cfqq_idle_window(cfqq) &&
2889 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2890 return true;
2891
2892 /*
2893 * Otherwise, we do only if they are the last ones
2894 * in their service tree.
2895 */
2896 if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
2897 !cfq_io_thinktime_big(cfqd, &st->ttime, false))
2898 return true;
2899 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
2900 return false;
2901}
2902
2903static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2904{
2905 struct cfq_queue *cfqq = cfqd->active_queue;
2906 struct cfq_rb_root *st = cfqq->service_tree;
2907 struct cfq_io_cq *cic;
2908 u64 sl, group_idle = 0;
2909 u64 now = ktime_get_ns();
2910
2911 /*
2912 * SSD device without seek penalty, disable idling. But only do so
2913 * for devices that support queuing, otherwise we still have a problem
2914 * with sync vs async workloads.
2915 */
2916 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag &&
2917 !cfqd->cfq_group_idle)
2918 return;
2919
2920 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2921 WARN_ON(cfq_cfqq_slice_new(cfqq));
2922
2923 /*
2924 * idle is disabled, either manually or by past process history
2925 */
2926 if (!cfq_should_idle(cfqd, cfqq)) {
2927 /* no queue idling. Check for group idling */
2928 if (cfqd->cfq_group_idle)
2929 group_idle = cfqd->cfq_group_idle;
2930 else
2931 return;
2932 }
2933
2934 /*
2935 * still active requests from this queue, don't idle
2936 */
2937 if (cfqq->dispatched)
2938 return;
2939
2940 /*
2941 * task has exited, don't wait
2942 */
2943 cic = cfqd->active_cic;
2944 if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2945 return;
2946
2947 /*
2948 * If our average think time is larger than the remaining time
2949 * slice, then don't idle. This avoids overrunning the allotted
2950 * time slice.
2951 */
2952 if (sample_valid(cic->ttime.ttime_samples) &&
2953 (cfqq->slice_end - now < cic->ttime.ttime_mean)) {
2954 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%llu",
2955 cic->ttime.ttime_mean);
2956 return;
2957 }
2958
2959 /*
2960 * There are other queues in the group or this is the only group and
2961 * it has too big thinktime, don't do group idle.
2962 */
2963 if (group_idle &&
2964 (cfqq->cfqg->nr_cfqq > 1 ||
2965 cfq_io_thinktime_big(cfqd, &st->ttime, true)))
2966 return;
2967
2968 cfq_mark_cfqq_wait_request(cfqq);
2969
2970 if (group_idle)
2971 sl = cfqd->cfq_group_idle;
2972 else
2973 sl = cfqd->cfq_slice_idle;
2974
2975 hrtimer_start(&cfqd->idle_slice_timer, ns_to_ktime(sl),
2976 HRTIMER_MODE_REL);
2977 cfqg_stats_set_start_idle_time(cfqq->cfqg);
2978 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %llu group_idle: %d", sl,
2979 group_idle ? 1 : 0);
2980}
2981
2982/*
2983 * Move request from internal lists to the request queue dispatch list.
2984 */
2985static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2986{
2987 struct cfq_data *cfqd = q->elevator->elevator_data;
2988 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2989
2990 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2991
2992 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2993 cfq_remove_request(rq);
2994 cfqq->dispatched++;
2995 (RQ_CFQG(rq))->dispatched++;
2996 elv_dispatch_sort(q, rq);
2997
2998 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2999 cfqq->nr_sectors += blk_rq_sectors(rq);
3000}
3001
3002/*
3003 * return expired entry, or NULL to just start from scratch in rbtree
3004 */
3005static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
3006{
3007 struct request *rq = NULL;
3008
3009 if (cfq_cfqq_fifo_expire(cfqq))
3010 return NULL;
3011
3012 cfq_mark_cfqq_fifo_expire(cfqq);
3013
3014 if (list_empty(&cfqq->fifo))
3015 return NULL;
3016
3017 rq = rq_entry_fifo(cfqq->fifo.next);
3018 if (ktime_get_ns() < rq->fifo_time)
3019 rq = NULL;
3020
3021 return rq;
3022}
3023
3024static inline int
3025cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3026{
3027 const int base_rq = cfqd->cfq_slice_async_rq;
3028
3029 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
3030
3031 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
3032}
3033
3034/*
3035 * Must be called with the queue_lock held.
3036 */
3037static int cfqq_process_refs(struct cfq_queue *cfqq)
3038{
3039 int process_refs, io_refs;
3040
3041 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
3042 process_refs = cfqq->ref - io_refs;
3043 BUG_ON(process_refs < 0);
3044 return process_refs;
3045}
3046
3047static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
3048{
3049 int process_refs, new_process_refs;
3050 struct cfq_queue *__cfqq;
3051
3052 /*
3053 * If there are no process references on the new_cfqq, then it is
3054 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
3055 * chain may have dropped their last reference (not just their
3056 * last process reference).
3057 */
3058 if (!cfqq_process_refs(new_cfqq))
3059 return;
3060
3061 /* Avoid a circular list and skip interim queue merges */
3062 while ((__cfqq = new_cfqq->new_cfqq)) {
3063 if (__cfqq == cfqq)
3064 return;
3065 new_cfqq = __cfqq;
3066 }
3067
3068 process_refs = cfqq_process_refs(cfqq);
3069 new_process_refs = cfqq_process_refs(new_cfqq);
3070 /*
3071 * If the process for the cfqq has gone away, there is no
3072 * sense in merging the queues.
3073 */
3074 if (process_refs == 0 || new_process_refs == 0)
3075 return;
3076
3077 /*
3078 * Merge in the direction of the lesser amount of work.
3079 */
3080 if (new_process_refs >= process_refs) {
3081 cfqq->new_cfqq = new_cfqq;
3082 new_cfqq->ref += process_refs;
3083 } else {
3084 new_cfqq->new_cfqq = cfqq;
3085 cfqq->ref += new_process_refs;
3086 }
3087}
3088
3089static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
3090 struct cfq_group *cfqg, enum wl_class_t wl_class)
3091{
3092 struct cfq_queue *queue;
3093 int i;
3094 bool key_valid = false;
3095 u64 lowest_key = 0;
3096 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
3097
3098 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
3099 /* select the one with lowest rb_key */
3100 queue = cfq_rb_first(st_for(cfqg, wl_class, i));
3101 if (queue &&
3102 (!key_valid || queue->rb_key < lowest_key)) {
3103 lowest_key = queue->rb_key;
3104 cur_best = i;
3105 key_valid = true;
3106 }
3107 }
3108
3109 return cur_best;
3110}
3111
3112static void
3113choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg)
3114{
3115 u64 slice;
3116 unsigned count;
3117 struct cfq_rb_root *st;
3118 u64 group_slice;
3119 enum wl_class_t original_class = cfqd->serving_wl_class;
3120 u64 now = ktime_get_ns();
3121
3122 /* Choose next priority. RT > BE > IDLE */
3123 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
3124 cfqd->serving_wl_class = RT_WORKLOAD;
3125 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
3126 cfqd->serving_wl_class = BE_WORKLOAD;
3127 else {
3128 cfqd->serving_wl_class = IDLE_WORKLOAD;
3129 cfqd->workload_expires = now + jiffies_to_nsecs(1);
3130 return;
3131 }
3132
3133 if (original_class != cfqd->serving_wl_class)
3134 goto new_workload;
3135
3136 /*
3137 * For RT and BE, we have to choose also the type
3138 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
3139 * expiration time
3140 */
3141 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3142 count = st->count;
3143
3144 /*
3145 * check workload expiration, and that we still have other queues ready
3146 */
3147 if (count && !(now > cfqd->workload_expires))
3148 return;
3149
3150new_workload:
3151 /* otherwise select new workload type */
3152 cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
3153 cfqd->serving_wl_class);
3154 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3155 count = st->count;
3156
3157 /*
3158 * the workload slice is computed as a fraction of target latency
3159 * proportional to the number of queues in that workload, over
3160 * all the queues in the same priority class
3161 */
3162 group_slice = cfq_group_slice(cfqd, cfqg);
3163
3164 slice = div_u64(group_slice * count,
3165 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
3166 cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
3167 cfqg)));
3168
3169 if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
3170 u64 tmp;
3171
3172 /*
3173 * Async queues are currently system wide. Just taking
3174 * proportion of queues with-in same group will lead to higher
3175 * async ratio system wide as generally root group is going
3176 * to have higher weight. A more accurate thing would be to
3177 * calculate system wide asnc/sync ratio.
3178 */
3179 tmp = cfqd->cfq_target_latency *
3180 cfqg_busy_async_queues(cfqd, cfqg);
3181 tmp = div_u64(tmp, cfqd->busy_queues);
3182 slice = min_t(u64, slice, tmp);
3183
3184 /* async workload slice is scaled down according to
3185 * the sync/async slice ratio. */
3186 slice = div64_u64(slice*cfqd->cfq_slice[0], cfqd->cfq_slice[1]);
3187 } else
3188 /* sync workload slice is at least 2 * cfq_slice_idle */
3189 slice = max(slice, 2 * cfqd->cfq_slice_idle);
3190
3191 slice = max_t(u64, slice, CFQ_MIN_TT);
3192 cfq_log(cfqd, "workload slice:%llu", slice);
3193 cfqd->workload_expires = now + slice;
3194}
3195
3196static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
3197{
3198 struct cfq_rb_root *st = &cfqd->grp_service_tree;
3199 struct cfq_group *cfqg;
3200
3201 if (RB_EMPTY_ROOT(&st->rb.rb_root))
3202 return NULL;
3203 cfqg = cfq_rb_first_group(st);
3204 update_min_vdisktime(st);
3205 return cfqg;
3206}
3207
3208static void cfq_choose_cfqg(struct cfq_data *cfqd)
3209{
3210 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
3211 u64 now = ktime_get_ns();
3212
3213 cfqd->serving_group = cfqg;
3214
3215 /* Restore the workload type data */
3216 if (cfqg->saved_wl_slice) {
3217 cfqd->workload_expires = now + cfqg->saved_wl_slice;
3218 cfqd->serving_wl_type = cfqg->saved_wl_type;
3219 cfqd->serving_wl_class = cfqg->saved_wl_class;
3220 } else
3221 cfqd->workload_expires = now - 1;
3222
3223 choose_wl_class_and_type(cfqd, cfqg);
3224}
3225
3226/*
3227 * Select a queue for service. If we have a current active queue,
3228 * check whether to continue servicing it, or retrieve and set a new one.
3229 */
3230static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
3231{
3232 struct cfq_queue *cfqq, *new_cfqq = NULL;
3233 u64 now = ktime_get_ns();
3234
3235 cfqq = cfqd->active_queue;
3236 if (!cfqq)
3237 goto new_queue;
3238
3239 if (!cfqd->rq_queued)
3240 return NULL;
3241
3242 /*
3243 * We were waiting for group to get backlogged. Expire the queue
3244 */
3245 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
3246 goto expire;
3247
3248 /*
3249 * The active queue has run out of time, expire it and select new.
3250 */
3251 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
3252 /*
3253 * If slice had not expired at the completion of last request
3254 * we might not have turned on wait_busy flag. Don't expire
3255 * the queue yet. Allow the group to get backlogged.
3256 *
3257 * The very fact that we have used the slice, that means we
3258 * have been idling all along on this queue and it should be
3259 * ok to wait for this request to complete.
3260 */
3261 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
3262 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3263 cfqq = NULL;
3264 goto keep_queue;
3265 } else
3266 goto check_group_idle;
3267 }
3268
3269 /*
3270 * The active queue has requests and isn't expired, allow it to
3271 * dispatch.
3272 */
3273 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3274 goto keep_queue;
3275
3276 /*
3277 * If another queue has a request waiting within our mean seek
3278 * distance, let it run. The expire code will check for close
3279 * cooperators and put the close queue at the front of the service
3280 * tree. If possible, merge the expiring queue with the new cfqq.
3281 */
3282 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
3283 if (new_cfqq) {
3284 if (!cfqq->new_cfqq)
3285 cfq_setup_merge(cfqq, new_cfqq);
3286 goto expire;
3287 }
3288
3289 /*
3290 * No requests pending. If the active queue still has requests in
3291 * flight or is idling for a new request, allow either of these
3292 * conditions to happen (or time out) before selecting a new queue.
3293 */
3294 if (hrtimer_active(&cfqd->idle_slice_timer)) {
3295 cfqq = NULL;
3296 goto keep_queue;
3297 }
3298
3299 /*
3300 * This is a deep seek queue, but the device is much faster than
3301 * the queue can deliver, don't idle
3302 **/
3303 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
3304 (cfq_cfqq_slice_new(cfqq) ||
3305 (cfqq->slice_end - now > now - cfqq->slice_start))) {
3306 cfq_clear_cfqq_deep(cfqq);
3307 cfq_clear_cfqq_idle_window(cfqq);
3308 }
3309
3310 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3311 cfqq = NULL;
3312 goto keep_queue;
3313 }
3314
3315 /*
3316 * If group idle is enabled and there are requests dispatched from
3317 * this group, wait for requests to complete.
3318 */
3319check_group_idle:
3320 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
3321 cfqq->cfqg->dispatched &&
3322 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
3323 cfqq = NULL;
3324 goto keep_queue;
3325 }
3326
3327expire:
3328 cfq_slice_expired(cfqd, 0);
3329new_queue:
3330 /*
3331 * Current queue expired. Check if we have to switch to a new
3332 * service tree
3333 */
3334 if (!new_cfqq)
3335 cfq_choose_cfqg(cfqd);
3336
3337 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
3338keep_queue:
3339 return cfqq;
3340}
3341
3342static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
3343{
3344 int dispatched = 0;
3345
3346 while (cfqq->next_rq) {
3347 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
3348 dispatched++;
3349 }
3350
3351 BUG_ON(!list_empty(&cfqq->fifo));
3352
3353 /* By default cfqq is not expired if it is empty. Do it explicitly */
3354 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
3355 return dispatched;
3356}
3357
3358/*
3359 * Drain our current requests. Used for barriers and when switching
3360 * io schedulers on-the-fly.
3361 */
3362static int cfq_forced_dispatch(struct cfq_data *cfqd)
3363{
3364 struct cfq_queue *cfqq;
3365 int dispatched = 0;
3366
3367 /* Expire the timeslice of the current active queue first */
3368 cfq_slice_expired(cfqd, 0);
3369 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
3370 __cfq_set_active_queue(cfqd, cfqq);
3371 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
3372 }
3373
3374 BUG_ON(cfqd->busy_queues);
3375
3376 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
3377 return dispatched;
3378}
3379
3380static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
3381 struct cfq_queue *cfqq)
3382{
3383 u64 now = ktime_get_ns();
3384
3385 /* the queue hasn't finished any request, can't estimate */
3386 if (cfq_cfqq_slice_new(cfqq))
3387 return true;
3388 if (now + cfqd->cfq_slice_idle * cfqq->dispatched > cfqq->slice_end)
3389 return true;
3390
3391 return false;
3392}
3393
3394static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3395{
3396 unsigned int max_dispatch;
3397
3398 if (cfq_cfqq_must_dispatch(cfqq))
3399 return true;
3400
3401 /*
3402 * Drain async requests before we start sync IO
3403 */
3404 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
3405 return false;
3406
3407 /*
3408 * If this is an async queue and we have sync IO in flight, let it wait
3409 */
3410 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
3411 return false;
3412
3413 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
3414 if (cfq_class_idle(cfqq))
3415 max_dispatch = 1;
3416
3417 /*
3418 * Does this cfqq already have too much IO in flight?
3419 */
3420 if (cfqq->dispatched >= max_dispatch) {
3421 bool promote_sync = false;
3422 /*
3423 * idle queue must always only have a single IO in flight
3424 */
3425 if (cfq_class_idle(cfqq))
3426 return false;
3427
3428 /*
3429 * If there is only one sync queue
3430 * we can ignore async queue here and give the sync
3431 * queue no dispatch limit. The reason is a sync queue can
3432 * preempt async queue, limiting the sync queue doesn't make
3433 * sense. This is useful for aiostress test.
3434 */
3435 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
3436 promote_sync = true;
3437
3438 /*
3439 * We have other queues, don't allow more IO from this one
3440 */
3441 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
3442 !promote_sync)
3443 return false;
3444
3445 /*
3446 * Sole queue user, no limit
3447 */
3448 if (cfqd->busy_queues == 1 || promote_sync)
3449 max_dispatch = -1;
3450 else
3451 /*
3452 * Normally we start throttling cfqq when cfq_quantum/2
3453 * requests have been dispatched. But we can drive
3454 * deeper queue depths at the beginning of slice
3455 * subjected to upper limit of cfq_quantum.
3456 * */
3457 max_dispatch = cfqd->cfq_quantum;
3458 }
3459
3460 /*
3461 * Async queues must wait a bit before being allowed dispatch.
3462 * We also ramp up the dispatch depth gradually for async IO,
3463 * based on the last sync IO we serviced
3464 */
3465 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
3466 u64 last_sync = ktime_get_ns() - cfqd->last_delayed_sync;
3467 unsigned int depth;
3468
3469 depth = div64_u64(last_sync, cfqd->cfq_slice[1]);
3470 if (!depth && !cfqq->dispatched)
3471 depth = 1;
3472 if (depth < max_dispatch)
3473 max_dispatch = depth;
3474 }
3475
3476 /*
3477 * If we're below the current max, allow a dispatch
3478 */
3479 return cfqq->dispatched < max_dispatch;
3480}
3481
3482/*
3483 * Dispatch a request from cfqq, moving them to the request queue
3484 * dispatch list.
3485 */
3486static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3487{
3488 struct request *rq;
3489
3490 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
3491
3492 rq = cfq_check_fifo(cfqq);
3493 if (rq)
3494 cfq_mark_cfqq_must_dispatch(cfqq);
3495
3496 if (!cfq_may_dispatch(cfqd, cfqq))
3497 return false;
3498
3499 /*
3500 * follow expired path, else get first next available
3501 */
3502 if (!rq)
3503 rq = cfqq->next_rq;
3504 else
3505 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
3506
3507 /*
3508 * insert request into driver dispatch list
3509 */
3510 cfq_dispatch_insert(cfqd->queue, rq);
3511
3512 if (!cfqd->active_cic) {
3513 struct cfq_io_cq *cic = RQ_CIC(rq);
3514
3515 atomic_long_inc(&cic->icq.ioc->refcount);
3516 cfqd->active_cic = cic;
3517 }
3518
3519 return true;
3520}
3521
3522/*
3523 * Find the cfqq that we need to service and move a request from that to the
3524 * dispatch list
3525 */
3526static int cfq_dispatch_requests(struct request_queue *q, int force)
3527{
3528 struct cfq_data *cfqd = q->elevator->elevator_data;
3529 struct cfq_queue *cfqq;
3530
3531 if (!cfqd->busy_queues)
3532 return 0;
3533
3534 if (unlikely(force))
3535 return cfq_forced_dispatch(cfqd);
3536
3537 cfqq = cfq_select_queue(cfqd);
3538 if (!cfqq)
3539 return 0;
3540
3541 /*
3542 * Dispatch a request from this cfqq, if it is allowed
3543 */
3544 if (!cfq_dispatch_request(cfqd, cfqq))
3545 return 0;
3546
3547 cfqq->slice_dispatch++;
3548 cfq_clear_cfqq_must_dispatch(cfqq);
3549
3550 /*
3551 * expire an async queue immediately if it has used up its slice. idle
3552 * queue always expire after 1 dispatch round.
3553 */
3554 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
3555 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
3556 cfq_class_idle(cfqq))) {
3557 cfqq->slice_end = ktime_get_ns() + 1;
3558 cfq_slice_expired(cfqd, 0);
3559 }
3560
3561 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
3562 return 1;
3563}
3564
3565/*
3566 * task holds one reference to the queue, dropped when task exits. each rq
3567 * in-flight on this queue also holds a reference, dropped when rq is freed.
3568 *
3569 * Each cfq queue took a reference on the parent group. Drop it now.
3570 * queue lock must be held here.
3571 */
3572static void cfq_put_queue(struct cfq_queue *cfqq)
3573{
3574 struct cfq_data *cfqd = cfqq->cfqd;
3575 struct cfq_group *cfqg;
3576
3577 BUG_ON(cfqq->ref <= 0);
3578
3579 cfqq->ref--;
3580 if (cfqq->ref)
3581 return;
3582
3583 cfq_log_cfqq(cfqd, cfqq, "put_queue");
3584 BUG_ON(rb_first(&cfqq->sort_list));
3585 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
3586 cfqg = cfqq->cfqg;
3587
3588 if (unlikely(cfqd->active_queue == cfqq)) {
3589 __cfq_slice_expired(cfqd, cfqq, 0);
3590 cfq_schedule_dispatch(cfqd);
3591 }
3592
3593 BUG_ON(cfq_cfqq_on_rr(cfqq));
3594 kmem_cache_free(cfq_pool, cfqq);
3595 cfqg_put(cfqg);
3596}
3597
3598static void cfq_put_cooperator(struct cfq_queue *cfqq)
3599{
3600 struct cfq_queue *__cfqq, *next;
3601
3602 /*
3603 * If this queue was scheduled to merge with another queue, be
3604 * sure to drop the reference taken on that queue (and others in
3605 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
3606 */
3607 __cfqq = cfqq->new_cfqq;
3608 while (__cfqq) {
3609 if (__cfqq == cfqq) {
3610 WARN(1, "cfqq->new_cfqq loop detected\n");
3611 break;
3612 }
3613 next = __cfqq->new_cfqq;
3614 cfq_put_queue(__cfqq);
3615 __cfqq = next;
3616 }
3617}
3618
3619static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3620{
3621 if (unlikely(cfqq == cfqd->active_queue)) {
3622 __cfq_slice_expired(cfqd, cfqq, 0);
3623 cfq_schedule_dispatch(cfqd);
3624 }
3625
3626 cfq_put_cooperator(cfqq);
3627
3628 cfq_put_queue(cfqq);
3629}
3630
3631static void cfq_init_icq(struct io_cq *icq)
3632{
3633 struct cfq_io_cq *cic = icq_to_cic(icq);
3634
3635 cic->ttime.last_end_request = ktime_get_ns();
3636}
3637
3638static void cfq_exit_icq(struct io_cq *icq)
3639{
3640 struct cfq_io_cq *cic = icq_to_cic(icq);
3641 struct cfq_data *cfqd = cic_to_cfqd(cic);
3642
3643 if (cic_to_cfqq(cic, false)) {
3644 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, false));
3645 cic_set_cfqq(cic, NULL, false);
3646 }
3647
3648 if (cic_to_cfqq(cic, true)) {
3649 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, true));
3650 cic_set_cfqq(cic, NULL, true);
3651 }
3652}
3653
3654static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3655{
3656 struct task_struct *tsk = current;
3657 int ioprio_class;
3658
3659 if (!cfq_cfqq_prio_changed(cfqq))
3660 return;
3661
3662 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3663 switch (ioprio_class) {
3664 default:
3665 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3666 case IOPRIO_CLASS_NONE:
3667 /*
3668 * no prio set, inherit CPU scheduling settings
3669 */
3670 cfqq->ioprio = task_nice_ioprio(tsk);
3671 cfqq->ioprio_class = task_nice_ioclass(tsk);
3672 break;
3673 case IOPRIO_CLASS_RT:
3674 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3675 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3676 break;
3677 case IOPRIO_CLASS_BE:
3678 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3679 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3680 break;
3681 case IOPRIO_CLASS_IDLE:
3682 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3683 cfqq->ioprio = 7;
3684 cfq_clear_cfqq_idle_window(cfqq);
3685 break;
3686 }
3687
3688 /*
3689 * keep track of original prio settings in case we have to temporarily
3690 * elevate the priority of this queue
3691 */
3692 cfqq->org_ioprio = cfqq->ioprio;
3693 cfqq->org_ioprio_class = cfqq->ioprio_class;
3694 cfq_clear_cfqq_prio_changed(cfqq);
3695}
3696
3697static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3698{
3699 int ioprio = cic->icq.ioc->ioprio;
3700 struct cfq_data *cfqd = cic_to_cfqd(cic);
3701 struct cfq_queue *cfqq;
3702
3703 /*
3704 * Check whether ioprio has changed. The condition may trigger
3705 * spuriously on a newly created cic but there's no harm.
3706 */
3707 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3708 return;
3709
3710 cfqq = cic_to_cfqq(cic, false);
3711 if (cfqq) {
3712 cfq_put_queue(cfqq);
3713 cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio);
3714 cic_set_cfqq(cic, cfqq, false);
3715 }
3716
3717 cfqq = cic_to_cfqq(cic, true);
3718 if (cfqq)
3719 cfq_mark_cfqq_prio_changed(cfqq);
3720
3721 cic->ioprio = ioprio;
3722}
3723
3724static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3725 pid_t pid, bool is_sync)
3726{
3727 RB_CLEAR_NODE(&cfqq->rb_node);
3728 RB_CLEAR_NODE(&cfqq->p_node);
3729 INIT_LIST_HEAD(&cfqq->fifo);
3730
3731 cfqq->ref = 0;
3732 cfqq->cfqd = cfqd;
3733
3734 cfq_mark_cfqq_prio_changed(cfqq);
3735
3736 if (is_sync) {
3737 if (!cfq_class_idle(cfqq))
3738 cfq_mark_cfqq_idle_window(cfqq);
3739 cfq_mark_cfqq_sync(cfqq);
3740 }
3741 cfqq->pid = pid;
3742}
3743
3744#ifdef CONFIG_CFQ_GROUP_IOSCHED
3745static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3746{
3747 struct cfq_data *cfqd = cic_to_cfqd(cic);
3748 struct cfq_queue *cfqq;
3749 uint64_t serial_nr;
3750
3751 rcu_read_lock();
3752 serial_nr = bio_blkcg(bio)->css.serial_nr;
3753 rcu_read_unlock();
3754
3755 /*
3756 * Check whether blkcg has changed. The condition may trigger
3757 * spuriously on a newly created cic but there's no harm.
3758 */
3759 if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))
3760 return;
3761
3762 /*
3763 * Drop reference to queues. New queues will be assigned in new
3764 * group upon arrival of fresh requests.
3765 */
3766 cfqq = cic_to_cfqq(cic, false);
3767 if (cfqq) {
3768 cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3769 cic_set_cfqq(cic, NULL, false);
3770 cfq_put_queue(cfqq);
3771 }
3772
3773 cfqq = cic_to_cfqq(cic, true);
3774 if (cfqq) {
3775 cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3776 cic_set_cfqq(cic, NULL, true);
3777 cfq_put_queue(cfqq);
3778 }
3779
3780 cic->blkcg_serial_nr = serial_nr;
3781}
3782#else
3783static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3784{
3785}
3786#endif /* CONFIG_CFQ_GROUP_IOSCHED */
3787
3788static struct cfq_queue **
3789cfq_async_queue_prio(struct cfq_group *cfqg, int ioprio_class, int ioprio)
3790{
3791 switch (ioprio_class) {
3792 case IOPRIO_CLASS_RT:
3793 return &cfqg->async_cfqq[0][ioprio];
3794 case IOPRIO_CLASS_NONE:
3795 ioprio = IOPRIO_NORM;
3796 /* fall through */
3797 case IOPRIO_CLASS_BE:
3798 return &cfqg->async_cfqq[1][ioprio];
3799 case IOPRIO_CLASS_IDLE:
3800 return &cfqg->async_idle_cfqq;
3801 default:
3802 BUG();
3803 }
3804}
3805
3806static struct cfq_queue *
3807cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3808 struct bio *bio)
3809{
3810 int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3811 int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3812 struct cfq_queue **async_cfqq = NULL;
3813 struct cfq_queue *cfqq;
3814 struct cfq_group *cfqg;
3815
3816 rcu_read_lock();
3817 cfqg = cfq_lookup_cfqg(cfqd, bio_blkcg(bio));
3818 if (!cfqg) {
3819 cfqq = &cfqd->oom_cfqq;
3820 goto out;
3821 }
3822
3823 if (!is_sync) {
3824 if (!ioprio_valid(cic->ioprio)) {
3825 struct task_struct *tsk = current;
3826 ioprio = task_nice_ioprio(tsk);
3827 ioprio_class = task_nice_ioclass(tsk);
3828 }
3829 async_cfqq = cfq_async_queue_prio(cfqg, ioprio_class, ioprio);
3830 cfqq = *async_cfqq;
3831 if (cfqq)
3832 goto out;
3833 }
3834
3835 cfqq = kmem_cache_alloc_node(cfq_pool,
3836 GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN,
3837 cfqd->queue->node);
3838 if (!cfqq) {
3839 cfqq = &cfqd->oom_cfqq;
3840 goto out;
3841 }
3842
3843 /* cfq_init_cfqq() assumes cfqq->ioprio_class is initialized. */
3844 cfqq->ioprio_class = IOPRIO_CLASS_NONE;
3845 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3846 cfq_init_prio_data(cfqq, cic);
3847 cfq_link_cfqq_cfqg(cfqq, cfqg);
3848 cfq_log_cfqq(cfqd, cfqq, "alloced");
3849
3850 if (async_cfqq) {
3851 /* a new async queue is created, pin and remember */
3852 cfqq->ref++;
3853 *async_cfqq = cfqq;
3854 }
3855out:
3856 cfqq->ref++;
3857 rcu_read_unlock();
3858 return cfqq;
3859}
3860
3861static void
3862__cfq_update_io_thinktime(struct cfq_ttime *ttime, u64 slice_idle)
3863{
3864 u64 elapsed = ktime_get_ns() - ttime->last_end_request;
3865 elapsed = min(elapsed, 2UL * slice_idle);
3866
3867 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3868 ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed, 8);
3869 ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
3870 ttime->ttime_samples);
3871}
3872
3873static void
3874cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3875 struct cfq_io_cq *cic)
3876{
3877 if (cfq_cfqq_sync(cfqq)) {
3878 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3879 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3880 cfqd->cfq_slice_idle);
3881 }
3882#ifdef CONFIG_CFQ_GROUP_IOSCHED
3883 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3884#endif
3885}
3886
3887static void
3888cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3889 struct request *rq)
3890{
3891 sector_t sdist = 0;
3892 sector_t n_sec = blk_rq_sectors(rq);
3893 if (cfqq->last_request_pos) {
3894 if (cfqq->last_request_pos < blk_rq_pos(rq))
3895 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3896 else
3897 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3898 }
3899
3900 cfqq->seek_history <<= 1;
3901 if (blk_queue_nonrot(cfqd->queue))
3902 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3903 else
3904 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3905}
3906
3907static inline bool req_noidle(struct request *req)
3908{
3909 return req_op(req) == REQ_OP_WRITE &&
3910 (req->cmd_flags & (REQ_SYNC | REQ_IDLE)) == REQ_SYNC;
3911}
3912
3913/*
3914 * Disable idle window if the process thinks too long or seeks so much that
3915 * it doesn't matter
3916 */
3917static void
3918cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3919 struct cfq_io_cq *cic)
3920{
3921 int old_idle, enable_idle;
3922
3923 /*
3924 * Don't idle for async or idle io prio class
3925 */
3926 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3927 return;
3928
3929 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3930
3931 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3932 cfq_mark_cfqq_deep(cfqq);
3933
3934 if (cfqq->next_rq && req_noidle(cfqq->next_rq))
3935 enable_idle = 0;
3936 else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3937 !cfqd->cfq_slice_idle ||
3938 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3939 enable_idle = 0;
3940 else if (sample_valid(cic->ttime.ttime_samples)) {
3941 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3942 enable_idle = 0;
3943 else
3944 enable_idle = 1;
3945 }
3946
3947 if (old_idle != enable_idle) {
3948 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3949 if (enable_idle)
3950 cfq_mark_cfqq_idle_window(cfqq);
3951 else
3952 cfq_clear_cfqq_idle_window(cfqq);
3953 }
3954}
3955
3956/*
3957 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3958 * no or if we aren't sure, a 1 will cause a preempt.
3959 */
3960static bool
3961cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3962 struct request *rq)
3963{
3964 struct cfq_queue *cfqq;
3965
3966 cfqq = cfqd->active_queue;
3967 if (!cfqq)
3968 return false;
3969
3970 if (cfq_class_idle(new_cfqq))
3971 return false;
3972
3973 if (cfq_class_idle(cfqq))
3974 return true;
3975
3976 /*
3977 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3978 */
3979 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3980 return false;
3981
3982 /*
3983 * if the new request is sync, but the currently running queue is
3984 * not, let the sync request have priority.
3985 */
3986 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
3987 return true;
3988
3989 /*
3990 * Treat ancestors of current cgroup the same way as current cgroup.
3991 * For anybody else we disallow preemption to guarantee service
3992 * fairness among cgroups.
3993 */
3994 if (!cfqg_is_descendant(cfqq->cfqg, new_cfqq->cfqg))
3995 return false;
3996
3997 if (cfq_slice_used(cfqq))
3998 return true;
3999
4000 /*
4001 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
4002 */
4003 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
4004 return true;
4005
4006 WARN_ON_ONCE(cfqq->ioprio_class != new_cfqq->ioprio_class);
4007 /* Allow preemption only if we are idling on sync-noidle tree */
4008 if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
4009 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
4010 RB_EMPTY_ROOT(&cfqq->sort_list))
4011 return true;
4012
4013 /*
4014 * So both queues are sync. Let the new request get disk time if
4015 * it's a metadata request and the current queue is doing regular IO.
4016 */
4017 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
4018 return true;
4019
4020 /* An idle queue should not be idle now for some reason */
4021 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
4022 return true;
4023
4024 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
4025 return false;
4026
4027 /*
4028 * if this request is as-good as one we would expect from the
4029 * current cfqq, let it preempt
4030 */
4031 if (cfq_rq_close(cfqd, cfqq, rq))
4032 return true;
4033
4034 return false;
4035}
4036
4037/*
4038 * cfqq preempts the active queue. if we allowed preempt with no slice left,
4039 * let it have half of its nominal slice.
4040 */
4041static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
4042{
4043 enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
4044
4045 cfq_log_cfqq(cfqd, cfqq, "preempt");
4046 cfq_slice_expired(cfqd, 1);
4047
4048 /*
4049 * workload type is changed, don't save slice, otherwise preempt
4050 * doesn't happen
4051 */
4052 if (old_type != cfqq_type(cfqq))
4053 cfqq->cfqg->saved_wl_slice = 0;
4054
4055 /*
4056 * Put the new queue at the front of the of the current list,
4057 * so we know that it will be selected next.
4058 */
4059 BUG_ON(!cfq_cfqq_on_rr(cfqq));
4060
4061 cfq_service_tree_add(cfqd, cfqq, 1);
4062
4063 cfqq->slice_end = 0;
4064 cfq_mark_cfqq_slice_new(cfqq);
4065}
4066
4067/*
4068 * Called when a new fs request (rq) is added (to cfqq). Check if there's
4069 * something we should do about it
4070 */
4071static void
4072cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
4073 struct request *rq)
4074{
4075 struct cfq_io_cq *cic = RQ_CIC(rq);
4076
4077 cfqd->rq_queued++;
4078 if (rq->cmd_flags & REQ_PRIO)
4079 cfqq->prio_pending++;
4080
4081 cfq_update_io_thinktime(cfqd, cfqq, cic);
4082 cfq_update_io_seektime(cfqd, cfqq, rq);
4083 cfq_update_idle_window(cfqd, cfqq, cic);
4084
4085 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
4086
4087 if (cfqq == cfqd->active_queue) {
4088 /*
4089 * Remember that we saw a request from this process, but
4090 * don't start queuing just yet. Otherwise we risk seeing lots
4091 * of tiny requests, because we disrupt the normal plugging
4092 * and merging. If the request is already larger than a single
4093 * page, let it rip immediately. For that case we assume that
4094 * merging is already done. Ditto for a busy system that
4095 * has other work pending, don't risk delaying until the
4096 * idle timer unplug to continue working.
4097 */
4098 if (cfq_cfqq_wait_request(cfqq)) {
4099 if (blk_rq_bytes(rq) > PAGE_SIZE ||
4100 cfqd->busy_queues > 1) {
4101 cfq_del_timer(cfqd, cfqq);
4102 cfq_clear_cfqq_wait_request(cfqq);
4103 __blk_run_queue(cfqd->queue);
4104 } else {
4105 cfqg_stats_update_idle_time(cfqq->cfqg);
4106 cfq_mark_cfqq_must_dispatch(cfqq);
4107 }
4108 }
4109 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
4110 /*
4111 * not the active queue - expire current slice if it is
4112 * idle and has expired it's mean thinktime or this new queue
4113 * has some old slice time left and is of higher priority or
4114 * this new queue is RT and the current one is BE
4115 */
4116 cfq_preempt_queue(cfqd, cfqq);
4117 __blk_run_queue(cfqd->queue);
4118 }
4119}
4120
4121static void cfq_insert_request(struct request_queue *q, struct request *rq)
4122{
4123 struct cfq_data *cfqd = q->elevator->elevator_data;
4124 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4125
4126 cfq_log_cfqq(cfqd, cfqq, "insert_request");
4127 cfq_init_prio_data(cfqq, RQ_CIC(rq));
4128
4129 rq->fifo_time = ktime_get_ns() + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
4130 list_add_tail(&rq->queuelist, &cfqq->fifo);
4131 cfq_add_rq_rb(rq);
4132 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
4133 rq->cmd_flags);
4134 cfq_rq_enqueued(cfqd, cfqq, rq);
4135}
4136
4137/*
4138 * Update hw_tag based on peak queue depth over 50 samples under
4139 * sufficient load.
4140 */
4141static void cfq_update_hw_tag(struct cfq_data *cfqd)
4142{
4143 struct cfq_queue *cfqq = cfqd->active_queue;
4144
4145 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
4146 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
4147
4148 if (cfqd->hw_tag == 1)
4149 return;
4150
4151 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
4152 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
4153 return;
4154
4155 /*
4156 * If active queue hasn't enough requests and can idle, cfq might not
4157 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
4158 * case
4159 */
4160 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
4161 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
4162 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
4163 return;
4164
4165 if (cfqd->hw_tag_samples++ < 50)
4166 return;
4167
4168 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
4169 cfqd->hw_tag = 1;
4170 else
4171 cfqd->hw_tag = 0;
4172}
4173
4174static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
4175{
4176 struct cfq_io_cq *cic = cfqd->active_cic;
4177 u64 now = ktime_get_ns();
4178
4179 /* If the queue already has requests, don't wait */
4180 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4181 return false;
4182
4183 /* If there are other queues in the group, don't wait */
4184 if (cfqq->cfqg->nr_cfqq > 1)
4185 return false;
4186
4187 /* the only queue in the group, but think time is big */
4188 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
4189 return false;
4190
4191 if (cfq_slice_used(cfqq))
4192 return true;
4193
4194 /* if slice left is less than think time, wait busy */
4195 if (cic && sample_valid(cic->ttime.ttime_samples)
4196 && (cfqq->slice_end - now < cic->ttime.ttime_mean))
4197 return true;
4198
4199 /*
4200 * If think times is less than a jiffy than ttime_mean=0 and above
4201 * will not be true. It might happen that slice has not expired yet
4202 * but will expire soon (4-5 ns) during select_queue(). To cover the
4203 * case where think time is less than a jiffy, mark the queue wait
4204 * busy if only 1 jiffy is left in the slice.
4205 */
4206 if (cfqq->slice_end - now <= jiffies_to_nsecs(1))
4207 return true;
4208
4209 return false;
4210}
4211
4212static void cfq_completed_request(struct request_queue *q, struct request *rq)
4213{
4214 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4215 struct cfq_data *cfqd = cfqq->cfqd;
4216 const int sync = rq_is_sync(rq);
4217 u64 now = ktime_get_ns();
4218
4219 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", req_noidle(rq));
4220
4221 cfq_update_hw_tag(cfqd);
4222
4223 WARN_ON(!cfqd->rq_in_driver);
4224 WARN_ON(!cfqq->dispatched);
4225 cfqd->rq_in_driver--;
4226 cfqq->dispatched--;
4227 (RQ_CFQG(rq))->dispatched--;
4228 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
4229 rq_io_start_time_ns(rq), rq->cmd_flags);
4230
4231 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
4232
4233 if (sync) {
4234 struct cfq_rb_root *st;
4235
4236 RQ_CIC(rq)->ttime.last_end_request = now;
4237
4238 if (cfq_cfqq_on_rr(cfqq))
4239 st = cfqq->service_tree;
4240 else
4241 st = st_for(cfqq->cfqg, cfqq_class(cfqq),
4242 cfqq_type(cfqq));
4243
4244 st->ttime.last_end_request = now;
4245 /*
4246 * We have to do this check in jiffies since start_time is in
4247 * jiffies and it is not trivial to convert to ns. If
4248 * cfq_fifo_expire[1] ever comes close to 1 jiffie, this test
4249 * will become problematic but so far we are fine (the default
4250 * is 128 ms).
4251 */
4252 if (!time_after(rq->start_time +
4253 nsecs_to_jiffies(cfqd->cfq_fifo_expire[1]),
4254 jiffies))
4255 cfqd->last_delayed_sync = now;
4256 }
4257
4258#ifdef CONFIG_CFQ_GROUP_IOSCHED
4259 cfqq->cfqg->ttime.last_end_request = now;
4260#endif
4261
4262 /*
4263 * If this is the active queue, check if it needs to be expired,
4264 * or if we want to idle in case it has no pending requests.
4265 */
4266 if (cfqd->active_queue == cfqq) {
4267 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
4268
4269 if (cfq_cfqq_slice_new(cfqq)) {
4270 cfq_set_prio_slice(cfqd, cfqq);
4271 cfq_clear_cfqq_slice_new(cfqq);
4272 }
4273
4274 /*
4275 * Should we wait for next request to come in before we expire
4276 * the queue.
4277 */
4278 if (cfq_should_wait_busy(cfqd, cfqq)) {
4279 u64 extend_sl = cfqd->cfq_slice_idle;
4280 if (!cfqd->cfq_slice_idle)
4281 extend_sl = cfqd->cfq_group_idle;
4282 cfqq->slice_end = now + extend_sl;
4283 cfq_mark_cfqq_wait_busy(cfqq);
4284 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
4285 }
4286
4287 /*
4288 * Idling is not enabled on:
4289 * - expired queues
4290 * - idle-priority queues
4291 * - async queues
4292 * - queues with still some requests queued
4293 * - when there is a close cooperator
4294 */
4295 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
4296 cfq_slice_expired(cfqd, 1);
4297 else if (sync && cfqq_empty &&
4298 !cfq_close_cooperator(cfqd, cfqq)) {
4299 cfq_arm_slice_timer(cfqd);
4300 }
4301 }
4302
4303 if (!cfqd->rq_in_driver)
4304 cfq_schedule_dispatch(cfqd);
4305}
4306
4307static void cfqq_boost_on_prio(struct cfq_queue *cfqq, unsigned int op)
4308{
4309 /*
4310 * If REQ_PRIO is set, boost class and prio level, if it's below
4311 * BE/NORM. If prio is not set, restore the potentially boosted
4312 * class/prio level.
4313 */
4314 if (!(op & REQ_PRIO)) {
4315 cfqq->ioprio_class = cfqq->org_ioprio_class;
4316 cfqq->ioprio = cfqq->org_ioprio;
4317 } else {
4318 if (cfq_class_idle(cfqq))
4319 cfqq->ioprio_class = IOPRIO_CLASS_BE;
4320 if (cfqq->ioprio > IOPRIO_NORM)
4321 cfqq->ioprio = IOPRIO_NORM;
4322 }
4323}
4324
4325static inline int __cfq_may_queue(struct cfq_queue *cfqq)
4326{
4327 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
4328 cfq_mark_cfqq_must_alloc_slice(cfqq);
4329 return ELV_MQUEUE_MUST;
4330 }
4331
4332 return ELV_MQUEUE_MAY;
4333}
4334
4335static int cfq_may_queue(struct request_queue *q, unsigned int op)
4336{
4337 struct cfq_data *cfqd = q->elevator->elevator_data;
4338 struct task_struct *tsk = current;
4339 struct cfq_io_cq *cic;
4340 struct cfq_queue *cfqq;
4341
4342 /*
4343 * don't force setup of a queue from here, as a call to may_queue
4344 * does not necessarily imply that a request actually will be queued.
4345 * so just lookup a possibly existing queue, or return 'may queue'
4346 * if that fails
4347 */
4348 cic = cfq_cic_lookup(cfqd, tsk->io_context);
4349 if (!cic)
4350 return ELV_MQUEUE_MAY;
4351
4352 cfqq = cic_to_cfqq(cic, op_is_sync(op));
4353 if (cfqq) {
4354 cfq_init_prio_data(cfqq, cic);
4355 cfqq_boost_on_prio(cfqq, op);
4356
4357 return __cfq_may_queue(cfqq);
4358 }
4359
4360 return ELV_MQUEUE_MAY;
4361}
4362
4363/*
4364 * queue lock held here
4365 */
4366static void cfq_put_request(struct request *rq)
4367{
4368 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4369
4370 if (cfqq) {
4371 const int rw = rq_data_dir(rq);
4372
4373 BUG_ON(!cfqq->allocated[rw]);
4374 cfqq->allocated[rw]--;
4375
4376 /* Put down rq reference on cfqg */
4377 cfqg_put(RQ_CFQG(rq));
4378 rq->elv.priv[0] = NULL;
4379 rq->elv.priv[1] = NULL;
4380
4381 cfq_put_queue(cfqq);
4382 }
4383}
4384
4385static struct cfq_queue *
4386cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
4387 struct cfq_queue *cfqq)
4388{
4389 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
4390 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
4391 cfq_mark_cfqq_coop(cfqq->new_cfqq);
4392 cfq_put_queue(cfqq);
4393 return cic_to_cfqq(cic, 1);
4394}
4395
4396/*
4397 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
4398 * was the last process referring to said cfqq.
4399 */
4400static struct cfq_queue *
4401split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
4402{
4403 if (cfqq_process_refs(cfqq) == 1) {
4404 cfqq->pid = current->pid;
4405 cfq_clear_cfqq_coop(cfqq);
4406 cfq_clear_cfqq_split_coop(cfqq);
4407 return cfqq;
4408 }
4409
4410 cic_set_cfqq(cic, NULL, 1);
4411
4412 cfq_put_cooperator(cfqq);
4413
4414 cfq_put_queue(cfqq);
4415 return NULL;
4416}
4417/*
4418 * Allocate cfq data structures associated with this request.
4419 */
4420static int
4421cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
4422 gfp_t gfp_mask)
4423{
4424 struct cfq_data *cfqd = q->elevator->elevator_data;
4425 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
4426 const int rw = rq_data_dir(rq);
4427 const bool is_sync = rq_is_sync(rq);
4428 struct cfq_queue *cfqq;
4429
4430 spin_lock_irq(q->queue_lock);
4431
4432 check_ioprio_changed(cic, bio);
4433 check_blkcg_changed(cic, bio);
4434new_queue:
4435 cfqq = cic_to_cfqq(cic, is_sync);
4436 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
4437 if (cfqq)
4438 cfq_put_queue(cfqq);
4439 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio);
4440 cic_set_cfqq(cic, cfqq, is_sync);
4441 } else {
4442 /*
4443 * If the queue was seeky for too long, break it apart.
4444 */
4445 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
4446 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
4447 cfqq = split_cfqq(cic, cfqq);
4448 if (!cfqq)
4449 goto new_queue;
4450 }
4451
4452 /*
4453 * Check to see if this queue is scheduled to merge with
4454 * another, closely cooperating queue. The merging of
4455 * queues happens here as it must be done in process context.
4456 * The reference on new_cfqq was taken in merge_cfqqs.
4457 */
4458 if (cfqq->new_cfqq)
4459 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
4460 }
4461
4462 cfqq->allocated[rw]++;
4463
4464 cfqq->ref++;
4465 cfqg_get(cfqq->cfqg);
4466 rq->elv.priv[0] = cfqq;
4467 rq->elv.priv[1] = cfqq->cfqg;
4468 spin_unlock_irq(q->queue_lock);
4469
4470 return 0;
4471}
4472
4473static void cfq_kick_queue(struct work_struct *work)
4474{
4475 struct cfq_data *cfqd =
4476 container_of(work, struct cfq_data, unplug_work);
4477 struct request_queue *q = cfqd->queue;
4478
4479 spin_lock_irq(q->queue_lock);
4480 __blk_run_queue(cfqd->queue);
4481 spin_unlock_irq(q->queue_lock);
4482}
4483
4484/*
4485 * Timer running if the active_queue is currently idling inside its time slice
4486 */
4487static enum hrtimer_restart cfq_idle_slice_timer(struct hrtimer *timer)
4488{
4489 struct cfq_data *cfqd = container_of(timer, struct cfq_data,
4490 idle_slice_timer);
4491 struct cfq_queue *cfqq;
4492 unsigned long flags;
4493 int timed_out = 1;
4494
4495 cfq_log(cfqd, "idle timer fired");
4496
4497 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
4498
4499 cfqq = cfqd->active_queue;
4500 if (cfqq) {
4501 timed_out = 0;
4502
4503 /*
4504 * We saw a request before the queue expired, let it through
4505 */
4506 if (cfq_cfqq_must_dispatch(cfqq))
4507 goto out_kick;
4508
4509 /*
4510 * expired
4511 */
4512 if (cfq_slice_used(cfqq))
4513 goto expire;
4514
4515 /*
4516 * only expire and reinvoke request handler, if there are
4517 * other queues with pending requests
4518 */
4519 if (!cfqd->busy_queues)
4520 goto out_cont;
4521
4522 /*
4523 * not expired and it has a request pending, let it dispatch
4524 */
4525 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4526 goto out_kick;
4527
4528 /*
4529 * Queue depth flag is reset only when the idle didn't succeed
4530 */
4531 cfq_clear_cfqq_deep(cfqq);
4532 }
4533expire:
4534 cfq_slice_expired(cfqd, timed_out);
4535out_kick:
4536 cfq_schedule_dispatch(cfqd);
4537out_cont:
4538 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
4539 return HRTIMER_NORESTART;
4540}
4541
4542static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
4543{
4544 hrtimer_cancel(&cfqd->idle_slice_timer);
4545 cancel_work_sync(&cfqd->unplug_work);
4546}
4547
4548static void cfq_exit_queue(struct elevator_queue *e)
4549{
4550 struct cfq_data *cfqd = e->elevator_data;
4551 struct request_queue *q = cfqd->queue;
4552
4553 cfq_shutdown_timer_wq(cfqd);
4554
4555 spin_lock_irq(q->queue_lock);
4556
4557 if (cfqd->active_queue)
4558 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
4559
4560 spin_unlock_irq(q->queue_lock);
4561
4562 cfq_shutdown_timer_wq(cfqd);
4563
4564#ifdef CONFIG_CFQ_GROUP_IOSCHED
4565 blkcg_deactivate_policy(q, &blkcg_policy_cfq);
4566#else
4567 kfree(cfqd->root_group);
4568#endif
4569 kfree(cfqd);
4570}
4571
4572static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
4573{
4574 struct cfq_data *cfqd;
4575 struct blkcg_gq *blkg __maybe_unused;
4576 int i, ret;
4577 struct elevator_queue *eq;
4578
4579 eq = elevator_alloc(q, e);
4580 if (!eq)
4581 return -ENOMEM;
4582
4583 cfqd = kzalloc_node(sizeof(*cfqd), GFP_KERNEL, q->node);
4584 if (!cfqd) {
4585 kobject_put(&eq->kobj);
4586 return -ENOMEM;
4587 }
4588 eq->elevator_data = cfqd;
4589
4590 cfqd->queue = q;
4591 spin_lock_irq(q->queue_lock);
4592 q->elevator = eq;
4593 spin_unlock_irq(q->queue_lock);
4594
4595 /* Init root service tree */
4596 cfqd->grp_service_tree = CFQ_RB_ROOT;
4597
4598 /* Init root group and prefer root group over other groups by default */
4599#ifdef CONFIG_CFQ_GROUP_IOSCHED
4600 ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
4601 if (ret)
4602 goto out_free;
4603
4604 cfqd->root_group = blkg_to_cfqg(q->root_blkg);
4605#else
4606 ret = -ENOMEM;
4607 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
4608 GFP_KERNEL, cfqd->queue->node);
4609 if (!cfqd->root_group)
4610 goto out_free;
4611
4612 cfq_init_cfqg_base(cfqd->root_group);
4613 cfqd->root_group->weight = 2 * CFQ_WEIGHT_LEGACY_DFL;
4614 cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_LEGACY_DFL;
4615#endif
4616
4617 /*
4618 * Not strictly needed (since RB_ROOT just clears the node and we
4619 * zeroed cfqd on alloc), but better be safe in case someone decides
4620 * to add magic to the rb code
4621 */
4622 for (i = 0; i < CFQ_PRIO_LISTS; i++)
4623 cfqd->prio_trees[i] = RB_ROOT;
4624
4625 /*
4626 * Our fallback cfqq if cfq_get_queue() runs into OOM issues.
4627 * Grab a permanent reference to it, so that the normal code flow
4628 * will not attempt to free it. oom_cfqq is linked to root_group
4629 * but shouldn't hold a reference as it'll never be unlinked. Lose
4630 * the reference from linking right away.
4631 */
4632 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4633 cfqd->oom_cfqq.ref++;
4634
4635 spin_lock_irq(q->queue_lock);
4636 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4637 cfqg_put(cfqd->root_group);
4638 spin_unlock_irq(q->queue_lock);
4639
4640 hrtimer_init(&cfqd->idle_slice_timer, CLOCK_MONOTONIC,
4641 HRTIMER_MODE_REL);
4642 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4643
4644 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4645
4646 cfqd->cfq_quantum = cfq_quantum;
4647 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4648 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4649 cfqd->cfq_back_max = cfq_back_max;
4650 cfqd->cfq_back_penalty = cfq_back_penalty;
4651 cfqd->cfq_slice[0] = cfq_slice_async;
4652 cfqd->cfq_slice[1] = cfq_slice_sync;
4653 cfqd->cfq_target_latency = cfq_target_latency;
4654 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4655 cfqd->cfq_slice_idle = cfq_slice_idle;
4656 cfqd->cfq_group_idle = cfq_group_idle;
4657 cfqd->cfq_latency = 1;
4658 cfqd->hw_tag = -1;
4659 /*
4660 * we optimistically start assuming sync ops weren't delayed in last
4661 * second, in order to have larger depth for async operations.
4662 */
4663 cfqd->last_delayed_sync = ktime_get_ns() - NSEC_PER_SEC;
4664 return 0;
4665
4666out_free:
4667 kfree(cfqd);
4668 kobject_put(&eq->kobj);
4669 return ret;
4670}
4671
4672static void cfq_registered_queue(struct request_queue *q)
4673{
4674 struct elevator_queue *e = q->elevator;
4675 struct cfq_data *cfqd = e->elevator_data;
4676
4677 /*
4678 * Default to IOPS mode with no idling for SSDs
4679 */
4680 if (blk_queue_nonrot(q))
4681 cfqd->cfq_slice_idle = 0;
4682 wbt_disable_default(q);
4683}
4684
4685/*
4686 * sysfs parts below -->
4687 */
4688static ssize_t
4689cfq_var_show(unsigned int var, char *page)
4690{
4691 return sprintf(page, "%u\n", var);
4692}
4693
4694static void
4695cfq_var_store(unsigned int *var, const char *page)
4696{
4697 char *p = (char *) page;
4698
4699 *var = simple_strtoul(p, &p, 10);
4700}
4701
4702#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4703static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4704{ \
4705 struct cfq_data *cfqd = e->elevator_data; \
4706 u64 __data = __VAR; \
4707 if (__CONV) \
4708 __data = div_u64(__data, NSEC_PER_MSEC); \
4709 return cfq_var_show(__data, (page)); \
4710}
4711SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4712SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4713SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4714SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4715SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4716SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4717SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4718SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4719SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4720SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4721SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4722SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
4723#undef SHOW_FUNCTION
4724
4725#define USEC_SHOW_FUNCTION(__FUNC, __VAR) \
4726static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4727{ \
4728 struct cfq_data *cfqd = e->elevator_data; \
4729 u64 __data = __VAR; \
4730 __data = div_u64(__data, NSEC_PER_USEC); \
4731 return cfq_var_show(__data, (page)); \
4732}
4733USEC_SHOW_FUNCTION(cfq_slice_idle_us_show, cfqd->cfq_slice_idle);
4734USEC_SHOW_FUNCTION(cfq_group_idle_us_show, cfqd->cfq_group_idle);
4735USEC_SHOW_FUNCTION(cfq_slice_sync_us_show, cfqd->cfq_slice[1]);
4736USEC_SHOW_FUNCTION(cfq_slice_async_us_show, cfqd->cfq_slice[0]);
4737USEC_SHOW_FUNCTION(cfq_target_latency_us_show, cfqd->cfq_target_latency);
4738#undef USEC_SHOW_FUNCTION
4739
4740#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4741static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4742{ \
4743 struct cfq_data *cfqd = e->elevator_data; \
4744 unsigned int __data; \
4745 cfq_var_store(&__data, (page)); \
4746 if (__data < (MIN)) \
4747 __data = (MIN); \
4748 else if (__data > (MAX)) \
4749 __data = (MAX); \
4750 if (__CONV) \
4751 *(__PTR) = (u64)__data * NSEC_PER_MSEC; \
4752 else \
4753 *(__PTR) = __data; \
4754 return count; \
4755}
4756STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4757STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4758 UINT_MAX, 1);
4759STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4760 UINT_MAX, 1);
4761STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4762STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4763 UINT_MAX, 0);
4764STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4765STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4766STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4767STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4768STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4769 UINT_MAX, 0);
4770STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4771STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
4772#undef STORE_FUNCTION
4773
4774#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \
4775static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4776{ \
4777 struct cfq_data *cfqd = e->elevator_data; \
4778 unsigned int __data; \
4779 cfq_var_store(&__data, (page)); \
4780 if (__data < (MIN)) \
4781 __data = (MIN); \
4782 else if (__data > (MAX)) \
4783 __data = (MAX); \
4784 *(__PTR) = (u64)__data * NSEC_PER_USEC; \
4785 return count; \
4786}
4787USEC_STORE_FUNCTION(cfq_slice_idle_us_store, &cfqd->cfq_slice_idle, 0, UINT_MAX);
4788USEC_STORE_FUNCTION(cfq_group_idle_us_store, &cfqd->cfq_group_idle, 0, UINT_MAX);
4789USEC_STORE_FUNCTION(cfq_slice_sync_us_store, &cfqd->cfq_slice[1], 1, UINT_MAX);
4790USEC_STORE_FUNCTION(cfq_slice_async_us_store, &cfqd->cfq_slice[0], 1, UINT_MAX);
4791USEC_STORE_FUNCTION(cfq_target_latency_us_store, &cfqd->cfq_target_latency, 1, UINT_MAX);
4792#undef USEC_STORE_FUNCTION
4793
4794#define CFQ_ATTR(name) \
4795 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4796
4797static struct elv_fs_entry cfq_attrs[] = {
4798 CFQ_ATTR(quantum),
4799 CFQ_ATTR(fifo_expire_sync),
4800 CFQ_ATTR(fifo_expire_async),
4801 CFQ_ATTR(back_seek_max),
4802 CFQ_ATTR(back_seek_penalty),
4803 CFQ_ATTR(slice_sync),
4804 CFQ_ATTR(slice_sync_us),
4805 CFQ_ATTR(slice_async),
4806 CFQ_ATTR(slice_async_us),
4807 CFQ_ATTR(slice_async_rq),
4808 CFQ_ATTR(slice_idle),
4809 CFQ_ATTR(slice_idle_us),
4810 CFQ_ATTR(group_idle),
4811 CFQ_ATTR(group_idle_us),
4812 CFQ_ATTR(low_latency),
4813 CFQ_ATTR(target_latency),
4814 CFQ_ATTR(target_latency_us),
4815 __ATTR_NULL
4816};
4817
4818static struct elevator_type iosched_cfq = {
4819 .ops.sq = {
4820 .elevator_merge_fn = cfq_merge,
4821 .elevator_merged_fn = cfq_merged_request,
4822 .elevator_merge_req_fn = cfq_merged_requests,
4823 .elevator_allow_bio_merge_fn = cfq_allow_bio_merge,
4824 .elevator_allow_rq_merge_fn = cfq_allow_rq_merge,
4825 .elevator_bio_merged_fn = cfq_bio_merged,
4826 .elevator_dispatch_fn = cfq_dispatch_requests,
4827 .elevator_add_req_fn = cfq_insert_request,
4828 .elevator_activate_req_fn = cfq_activate_request,
4829 .elevator_deactivate_req_fn = cfq_deactivate_request,
4830 .elevator_completed_req_fn = cfq_completed_request,
4831 .elevator_former_req_fn = elv_rb_former_request,
4832 .elevator_latter_req_fn = elv_rb_latter_request,
4833 .elevator_init_icq_fn = cfq_init_icq,
4834 .elevator_exit_icq_fn = cfq_exit_icq,
4835 .elevator_set_req_fn = cfq_set_request,
4836 .elevator_put_req_fn = cfq_put_request,
4837 .elevator_may_queue_fn = cfq_may_queue,
4838 .elevator_init_fn = cfq_init_queue,
4839 .elevator_exit_fn = cfq_exit_queue,
4840 .elevator_registered_fn = cfq_registered_queue,
4841 },
4842 .icq_size = sizeof(struct cfq_io_cq),
4843 .icq_align = __alignof__(struct cfq_io_cq),
4844 .elevator_attrs = cfq_attrs,
4845 .elevator_name = "cfq",
4846 .elevator_owner = THIS_MODULE,
4847};
4848
4849#ifdef CONFIG_CFQ_GROUP_IOSCHED
4850static struct blkcg_policy blkcg_policy_cfq = {
4851 .dfl_cftypes = cfq_blkcg_files,
4852 .legacy_cftypes = cfq_blkcg_legacy_files,
4853
4854 .cpd_alloc_fn = cfq_cpd_alloc,
4855 .cpd_init_fn = cfq_cpd_init,
4856 .cpd_free_fn = cfq_cpd_free,
4857 .cpd_bind_fn = cfq_cpd_bind,
4858
4859 .pd_alloc_fn = cfq_pd_alloc,
4860 .pd_init_fn = cfq_pd_init,
4861 .pd_offline_fn = cfq_pd_offline,
4862 .pd_free_fn = cfq_pd_free,
4863 .pd_reset_stats_fn = cfq_pd_reset_stats,
4864};
4865#endif
4866
4867static int __init cfq_init(void)
4868{
4869 int ret;
4870
4871#ifdef CONFIG_CFQ_GROUP_IOSCHED
4872 ret = blkcg_policy_register(&blkcg_policy_cfq);
4873 if (ret)
4874 return ret;
4875#else
4876 cfq_group_idle = 0;
4877#endif
4878
4879 ret = -ENOMEM;
4880 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4881 if (!cfq_pool)
4882 goto err_pol_unreg;
4883
4884 ret = elv_register(&iosched_cfq);
4885 if (ret)
4886 goto err_free_pool;
4887
4888 return 0;
4889
4890err_free_pool:
4891 kmem_cache_destroy(cfq_pool);
4892err_pol_unreg:
4893#ifdef CONFIG_CFQ_GROUP_IOSCHED
4894 blkcg_policy_unregister(&blkcg_policy_cfq);
4895#endif
4896 return ret;
4897}
4898
4899static void __exit cfq_exit(void)
4900{
4901#ifdef CONFIG_CFQ_GROUP_IOSCHED
4902 blkcg_policy_unregister(&blkcg_policy_cfq);
4903#endif
4904 elv_unregister(&iosched_cfq);
4905 kmem_cache_destroy(cfq_pool);
4906}
4907
4908module_init(cfq_init);
4909module_exit(cfq_exit);
4910
4911MODULE_AUTHOR("Jens Axboe");
4912MODULE_LICENSE("GPL");
4913MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");