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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");