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1/*
2 * Header file for the BFQ I/O scheduler: data structures and
3 * prototypes of interface functions among BFQ components.
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation; either version 2 of the
8 * License, or (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 */
15#ifndef _BFQ_H
16#define _BFQ_H
17
18#include <linux/blktrace_api.h>
19#include <linux/hrtimer.h>
20#include <linux/blk-cgroup.h>
21
22#define BFQ_IOPRIO_CLASSES 3
23#define BFQ_CL_IDLE_TIMEOUT (HZ/5)
24
25#define BFQ_MIN_WEIGHT 1
26#define BFQ_MAX_WEIGHT 1000
27#define BFQ_WEIGHT_CONVERSION_COEFF 10
28
29#define BFQ_DEFAULT_QUEUE_IOPRIO 4
30
31#define BFQ_WEIGHT_LEGACY_DFL 100
32#define BFQ_DEFAULT_GRP_IOPRIO 0
33#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE
34
35/*
36 * Soft real-time applications are extremely more latency sensitive
37 * than interactive ones. Over-raise the weight of the former to
38 * privilege them against the latter.
39 */
40#define BFQ_SOFTRT_WEIGHT_FACTOR 100
41
42struct bfq_entity;
43
44/**
45 * struct bfq_service_tree - per ioprio_class service tree.
46 *
47 * Each service tree represents a B-WF2Q+ scheduler on its own. Each
48 * ioprio_class has its own independent scheduler, and so its own
49 * bfq_service_tree. All the fields are protected by the queue lock
50 * of the containing bfqd.
51 */
52struct bfq_service_tree {
53 /* tree for active entities (i.e., those backlogged) */
54 struct rb_root active;
55 /* tree for idle entities (i.e., not backlogged, with V < F_i)*/
56 struct rb_root idle;
57
58 /* idle entity with minimum F_i */
59 struct bfq_entity *first_idle;
60 /* idle entity with maximum F_i */
61 struct bfq_entity *last_idle;
62
63 /* scheduler virtual time */
64 u64 vtime;
65 /* scheduler weight sum; active and idle entities contribute to it */
66 unsigned long wsum;
67};
68
69/**
70 * struct bfq_sched_data - multi-class scheduler.
71 *
72 * bfq_sched_data is the basic scheduler queue. It supports three
73 * ioprio_classes, and can be used either as a toplevel queue or as an
74 * intermediate queue in a hierarchical setup.
75 *
76 * The supported ioprio_classes are the same as in CFQ, in descending
77 * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
78 * Requests from higher priority queues are served before all the
79 * requests from lower priority queues; among requests of the same
80 * queue requests are served according to B-WF2Q+.
81 *
82 * The schedule is implemented by the service trees, plus the field
83 * @next_in_service, which points to the entity on the active trees
84 * that will be served next, if 1) no changes in the schedule occurs
85 * before the current in-service entity is expired, 2) the in-service
86 * queue becomes idle when it expires, and 3) if the entity pointed by
87 * in_service_entity is not a queue, then the in-service child entity
88 * of the entity pointed by in_service_entity becomes idle on
89 * expiration. This peculiar definition allows for the following
90 * optimization, not yet exploited: while a given entity is still in
91 * service, we already know which is the best candidate for next
92 * service among the other active entitities in the same parent
93 * entity. We can then quickly compare the timestamps of the
94 * in-service entity with those of such best candidate.
95 *
96 * All fields are protected by the lock of the containing bfqd.
97 */
98struct bfq_sched_data {
99 /* entity in service */
100 struct bfq_entity *in_service_entity;
101 /* head-of-line entity (see comments above) */
102 struct bfq_entity *next_in_service;
103 /* array of service trees, one per ioprio_class */
104 struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
105 /* last time CLASS_IDLE was served */
106 unsigned long bfq_class_idle_last_service;
107
108};
109
110/**
111 * struct bfq_weight_counter - counter of the number of all active entities
112 * with a given weight.
113 */
114struct bfq_weight_counter {
115 unsigned int weight; /* weight of the entities this counter refers to */
116 unsigned int num_active; /* nr of active entities with this weight */
117 /*
118 * Weights tree member (see bfq_data's @queue_weights_tree and
119 * @group_weights_tree)
120 */
121 struct rb_node weights_node;
122};
123
124/**
125 * struct bfq_entity - schedulable entity.
126 *
127 * A bfq_entity is used to represent either a bfq_queue (leaf node in the
128 * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each
129 * entity belongs to the sched_data of the parent group in the cgroup
130 * hierarchy. Non-leaf entities have also their own sched_data, stored
131 * in @my_sched_data.
132 *
133 * Each entity stores independently its priority values; this would
134 * allow different weights on different devices, but this
135 * functionality is not exported to userspace by now. Priorities and
136 * weights are updated lazily, first storing the new values into the
137 * new_* fields, then setting the @prio_changed flag. As soon as
138 * there is a transition in the entity state that allows the priority
139 * update to take place the effective and the requested priority
140 * values are synchronized.
141 *
142 * Unless cgroups are used, the weight value is calculated from the
143 * ioprio to export the same interface as CFQ. When dealing with
144 * ``well-behaved'' queues (i.e., queues that do not spend too much
145 * time to consume their budget and have true sequential behavior, and
146 * when there are no external factors breaking anticipation) the
147 * relative weights at each level of the cgroups hierarchy should be
148 * guaranteed. All the fields are protected by the queue lock of the
149 * containing bfqd.
150 */
151struct bfq_entity {
152 /* service_tree member */
153 struct rb_node rb_node;
154 /* pointer to the weight counter associated with this entity */
155 struct bfq_weight_counter *weight_counter;
156
157 /*
158 * Flag, true if the entity is on a tree (either the active or
159 * the idle one of its service_tree) or is in service.
160 */
161 bool on_st;
162
163 /* B-WF2Q+ start and finish timestamps [sectors/weight] */
164 u64 start, finish;
165
166 /* tree the entity is enqueued into; %NULL if not on a tree */
167 struct rb_root *tree;
168
169 /*
170 * minimum start time of the (active) subtree rooted at this
171 * entity; used for O(log N) lookups into active trees
172 */
173 u64 min_start;
174
175 /* amount of service received during the last service slot */
176 int service;
177
178 /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
179 int budget;
180
181 /* weight of the queue */
182 int weight;
183 /* next weight if a change is in progress */
184 int new_weight;
185
186 /* original weight, used to implement weight boosting */
187 int orig_weight;
188
189 /* parent entity, for hierarchical scheduling */
190 struct bfq_entity *parent;
191
192 /*
193 * For non-leaf nodes in the hierarchy, the associated
194 * scheduler queue, %NULL on leaf nodes.
195 */
196 struct bfq_sched_data *my_sched_data;
197 /* the scheduler queue this entity belongs to */
198 struct bfq_sched_data *sched_data;
199
200 /* flag, set to request a weight, ioprio or ioprio_class change */
201 int prio_changed;
202};
203
204struct bfq_group;
205
206/**
207 * struct bfq_ttime - per process thinktime stats.
208 */
209struct bfq_ttime {
210 /* completion time of the last request */
211 u64 last_end_request;
212
213 /* total process thinktime */
214 u64 ttime_total;
215 /* number of thinktime samples */
216 unsigned long ttime_samples;
217 /* average process thinktime */
218 u64 ttime_mean;
219};
220
221/**
222 * struct bfq_queue - leaf schedulable entity.
223 *
224 * A bfq_queue is a leaf request queue; it can be associated with an
225 * io_context or more, if it is async or shared between cooperating
226 * processes. @cgroup holds a reference to the cgroup, to be sure that it
227 * does not disappear while a bfqq still references it (mostly to avoid
228 * races between request issuing and task migration followed by cgroup
229 * destruction).
230 * All the fields are protected by the queue lock of the containing bfqd.
231 */
232struct bfq_queue {
233 /* reference counter */
234 int ref;
235 /* parent bfq_data */
236 struct bfq_data *bfqd;
237
238 /* current ioprio and ioprio class */
239 unsigned short ioprio, ioprio_class;
240 /* next ioprio and ioprio class if a change is in progress */
241 unsigned short new_ioprio, new_ioprio_class;
242
243 /*
244 * Shared bfq_queue if queue is cooperating with one or more
245 * other queues.
246 */
247 struct bfq_queue *new_bfqq;
248 /* request-position tree member (see bfq_group's @rq_pos_tree) */
249 struct rb_node pos_node;
250 /* request-position tree root (see bfq_group's @rq_pos_tree) */
251 struct rb_root *pos_root;
252
253 /* sorted list of pending requests */
254 struct rb_root sort_list;
255 /* if fifo isn't expired, next request to serve */
256 struct request *next_rq;
257 /* number of sync and async requests queued */
258 int queued[2];
259 /* number of requests currently allocated */
260 int allocated;
261 /* number of pending metadata requests */
262 int meta_pending;
263 /* fifo list of requests in sort_list */
264 struct list_head fifo;
265
266 /* entity representing this queue in the scheduler */
267 struct bfq_entity entity;
268
269 /* maximum budget allowed from the feedback mechanism */
270 int max_budget;
271 /* budget expiration (in jiffies) */
272 unsigned long budget_timeout;
273
274 /* number of requests on the dispatch list or inside driver */
275 int dispatched;
276
277 /* status flags */
278 unsigned long flags;
279
280 /* node for active/idle bfqq list inside parent bfqd */
281 struct list_head bfqq_list;
282
283 /* associated @bfq_ttime struct */
284 struct bfq_ttime ttime;
285
286 /* bit vector: a 1 for each seeky requests in history */
287 u32 seek_history;
288
289 /* node for the device's burst list */
290 struct hlist_node burst_list_node;
291
292 /* position of the last request enqueued */
293 sector_t last_request_pos;
294
295 /* Number of consecutive pairs of request completion and
296 * arrival, such that the queue becomes idle after the
297 * completion, but the next request arrives within an idle
298 * time slice; used only if the queue's IO_bound flag has been
299 * cleared.
300 */
301 unsigned int requests_within_timer;
302
303 /* pid of the process owning the queue, used for logging purposes */
304 pid_t pid;
305
306 /*
307 * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
308 * if the queue is shared.
309 */
310 struct bfq_io_cq *bic;
311
312 /* current maximum weight-raising time for this queue */
313 unsigned long wr_cur_max_time;
314 /*
315 * Minimum time instant such that, only if a new request is
316 * enqueued after this time instant in an idle @bfq_queue with
317 * no outstanding requests, then the task associated with the
318 * queue it is deemed as soft real-time (see the comments on
319 * the function bfq_bfqq_softrt_next_start())
320 */
321 unsigned long soft_rt_next_start;
322 /*
323 * Start time of the current weight-raising period if
324 * the @bfq-queue is being weight-raised, otherwise
325 * finish time of the last weight-raising period.
326 */
327 unsigned long last_wr_start_finish;
328 /* factor by which the weight of this queue is multiplied */
329 unsigned int wr_coeff;
330 /*
331 * Time of the last transition of the @bfq_queue from idle to
332 * backlogged.
333 */
334 unsigned long last_idle_bklogged;
335 /*
336 * Cumulative service received from the @bfq_queue since the
337 * last transition from idle to backlogged.
338 */
339 unsigned long service_from_backlogged;
340 /*
341 * Cumulative service received from the @bfq_queue since its
342 * last transition to weight-raised state.
343 */
344 unsigned long service_from_wr;
345
346 /*
347 * Value of wr start time when switching to soft rt
348 */
349 unsigned long wr_start_at_switch_to_srt;
350
351 unsigned long split_time; /* time of last split */
352
353 unsigned long first_IO_time; /* time of first I/O for this queue */
354};
355
356/**
357 * struct bfq_io_cq - per (request_queue, io_context) structure.
358 */
359struct bfq_io_cq {
360 /* associated io_cq structure */
361 struct io_cq icq; /* must be the first member */
362 /* array of two process queues, the sync and the async */
363 struct bfq_queue *bfqq[2];
364 /* per (request_queue, blkcg) ioprio */
365 int ioprio;
366#ifdef CONFIG_BFQ_GROUP_IOSCHED
367 uint64_t blkcg_serial_nr; /* the current blkcg serial */
368#endif
369 /*
370 * Snapshot of the has_short_time flag before merging; taken
371 * to remember its value while the queue is merged, so as to
372 * be able to restore it in case of split.
373 */
374 bool saved_has_short_ttime;
375 /*
376 * Same purpose as the previous two fields for the I/O bound
377 * classification of a queue.
378 */
379 bool saved_IO_bound;
380
381 /*
382 * Same purpose as the previous fields for the value of the
383 * field keeping the queue's belonging to a large burst
384 */
385 bool saved_in_large_burst;
386 /*
387 * True if the queue belonged to a burst list before its merge
388 * with another cooperating queue.
389 */
390 bool was_in_burst_list;
391
392 /*
393 * Similar to previous fields: save wr information.
394 */
395 unsigned long saved_wr_coeff;
396 unsigned long saved_last_wr_start_finish;
397 unsigned long saved_wr_start_at_switch_to_srt;
398 unsigned int saved_wr_cur_max_time;
399 struct bfq_ttime saved_ttime;
400};
401
402enum bfq_device_speed {
403 BFQ_BFQD_FAST,
404 BFQ_BFQD_SLOW,
405};
406
407/**
408 * struct bfq_data - per-device data structure.
409 *
410 * All the fields are protected by @lock.
411 */
412struct bfq_data {
413 /* device request queue */
414 struct request_queue *queue;
415 /* dispatch queue */
416 struct list_head dispatch;
417
418 /* root bfq_group for the device */
419 struct bfq_group *root_group;
420
421 /*
422 * rbtree of weight counters of @bfq_queues, sorted by
423 * weight. Used to keep track of whether all @bfq_queues have
424 * the same weight. The tree contains one counter for each
425 * distinct weight associated to some active and not
426 * weight-raised @bfq_queue (see the comments to the functions
427 * bfq_weights_tree_[add|remove] for further details).
428 */
429 struct rb_root queue_weights_tree;
430 /*
431 * rbtree of non-queue @bfq_entity weight counters, sorted by
432 * weight. Used to keep track of whether all @bfq_groups have
433 * the same weight. The tree contains one counter for each
434 * distinct weight associated to some active @bfq_group (see
435 * the comments to the functions bfq_weights_tree_[add|remove]
436 * for further details).
437 */
438 struct rb_root group_weights_tree;
439
440 /*
441 * Number of bfq_queues containing requests (including the
442 * queue in service, even if it is idling).
443 */
444 int busy_queues;
445 /* number of weight-raised busy @bfq_queues */
446 int wr_busy_queues;
447 /* number of queued requests */
448 int queued;
449 /* number of requests dispatched and waiting for completion */
450 int rq_in_driver;
451
452 /*
453 * Maximum number of requests in driver in the last
454 * @hw_tag_samples completed requests.
455 */
456 int max_rq_in_driver;
457 /* number of samples used to calculate hw_tag */
458 int hw_tag_samples;
459 /* flag set to one if the driver is showing a queueing behavior */
460 int hw_tag;
461
462 /* number of budgets assigned */
463 int budgets_assigned;
464
465 /*
466 * Timer set when idling (waiting) for the next request from
467 * the queue in service.
468 */
469 struct hrtimer idle_slice_timer;
470
471 /* bfq_queue in service */
472 struct bfq_queue *in_service_queue;
473
474 /* on-disk position of the last served request */
475 sector_t last_position;
476
477 /* time of last request completion (ns) */
478 u64 last_completion;
479
480 /* time of first rq dispatch in current observation interval (ns) */
481 u64 first_dispatch;
482 /* time of last rq dispatch in current observation interval (ns) */
483 u64 last_dispatch;
484
485 /* beginning of the last budget */
486 ktime_t last_budget_start;
487 /* beginning of the last idle slice */
488 ktime_t last_idling_start;
489
490 /* number of samples in current observation interval */
491 int peak_rate_samples;
492 /* num of samples of seq dispatches in current observation interval */
493 u32 sequential_samples;
494 /* total num of sectors transferred in current observation interval */
495 u64 tot_sectors_dispatched;
496 /* max rq size seen during current observation interval (sectors) */
497 u32 last_rq_max_size;
498 /* time elapsed from first dispatch in current observ. interval (us) */
499 u64 delta_from_first;
500 /*
501 * Current estimate of the device peak rate, measured in
502 * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by
503 * BFQ_RATE_SHIFT is performed to increase precision in
504 * fixed-point calculations.
505 */
506 u32 peak_rate;
507
508 /* maximum budget allotted to a bfq_queue before rescheduling */
509 int bfq_max_budget;
510
511 /* list of all the bfq_queues active on the device */
512 struct list_head active_list;
513 /* list of all the bfq_queues idle on the device */
514 struct list_head idle_list;
515
516 /*
517 * Timeout for async/sync requests; when it fires, requests
518 * are served in fifo order.
519 */
520 u64 bfq_fifo_expire[2];
521 /* weight of backward seeks wrt forward ones */
522 unsigned int bfq_back_penalty;
523 /* maximum allowed backward seek */
524 unsigned int bfq_back_max;
525 /* maximum idling time */
526 u32 bfq_slice_idle;
527
528 /* user-configured max budget value (0 for auto-tuning) */
529 int bfq_user_max_budget;
530 /*
531 * Timeout for bfq_queues to consume their budget; used to
532 * prevent seeky queues from imposing long latencies to
533 * sequential or quasi-sequential ones (this also implies that
534 * seeky queues cannot receive guarantees in the service
535 * domain; after a timeout they are charged for the time they
536 * have been in service, to preserve fairness among them, but
537 * without service-domain guarantees).
538 */
539 unsigned int bfq_timeout;
540
541 /*
542 * Number of consecutive requests that must be issued within
543 * the idle time slice to set again idling to a queue which
544 * was marked as non-I/O-bound (see the definition of the
545 * IO_bound flag for further details).
546 */
547 unsigned int bfq_requests_within_timer;
548
549 /*
550 * Force device idling whenever needed to provide accurate
551 * service guarantees, without caring about throughput
552 * issues. CAVEAT: this may even increase latencies, in case
553 * of useless idling for processes that did stop doing I/O.
554 */
555 bool strict_guarantees;
556
557 /*
558 * Last time at which a queue entered the current burst of
559 * queues being activated shortly after each other; for more
560 * details about this and the following parameters related to
561 * a burst of activations, see the comments on the function
562 * bfq_handle_burst.
563 */
564 unsigned long last_ins_in_burst;
565 /*
566 * Reference time interval used to decide whether a queue has
567 * been activated shortly after @last_ins_in_burst.
568 */
569 unsigned long bfq_burst_interval;
570 /* number of queues in the current burst of queue activations */
571 int burst_size;
572
573 /* common parent entity for the queues in the burst */
574 struct bfq_entity *burst_parent_entity;
575 /* Maximum burst size above which the current queue-activation
576 * burst is deemed as 'large'.
577 */
578 unsigned long bfq_large_burst_thresh;
579 /* true if a large queue-activation burst is in progress */
580 bool large_burst;
581 /*
582 * Head of the burst list (as for the above fields, more
583 * details in the comments on the function bfq_handle_burst).
584 */
585 struct hlist_head burst_list;
586
587 /* if set to true, low-latency heuristics are enabled */
588 bool low_latency;
589 /*
590 * Maximum factor by which the weight of a weight-raised queue
591 * is multiplied.
592 */
593 unsigned int bfq_wr_coeff;
594 /* maximum duration of a weight-raising period (jiffies) */
595 unsigned int bfq_wr_max_time;
596
597 /* Maximum weight-raising duration for soft real-time processes */
598 unsigned int bfq_wr_rt_max_time;
599 /*
600 * Minimum idle period after which weight-raising may be
601 * reactivated for a queue (in jiffies).
602 */
603 unsigned int bfq_wr_min_idle_time;
604 /*
605 * Minimum period between request arrivals after which
606 * weight-raising may be reactivated for an already busy async
607 * queue (in jiffies).
608 */
609 unsigned long bfq_wr_min_inter_arr_async;
610
611 /* Max service-rate for a soft real-time queue, in sectors/sec */
612 unsigned int bfq_wr_max_softrt_rate;
613 /*
614 * Cached value of the product R*T, used for computing the
615 * maximum duration of weight raising automatically.
616 */
617 u64 RT_prod;
618 /* device-speed class for the low-latency heuristic */
619 enum bfq_device_speed device_speed;
620
621 /* fallback dummy bfqq for extreme OOM conditions */
622 struct bfq_queue oom_bfqq;
623
624 spinlock_t lock;
625
626 /*
627 * bic associated with the task issuing current bio for
628 * merging. This and the next field are used as a support to
629 * be able to perform the bic lookup, needed by bio-merge
630 * functions, before the scheduler lock is taken, and thus
631 * avoid taking the request-queue lock while the scheduler
632 * lock is being held.
633 */
634 struct bfq_io_cq *bio_bic;
635 /* bfqq associated with the task issuing current bio for merging */
636 struct bfq_queue *bio_bfqq;
637
638 /*
639 * Cached sbitmap shift, used to compute depth limits in
640 * bfq_update_depths.
641 */
642 unsigned int sb_shift;
643
644 /*
645 * Depth limits used in bfq_limit_depth (see comments on the
646 * function)
647 */
648 unsigned int word_depths[2][2];
649};
650
651enum bfqq_state_flags {
652 BFQQF_just_created = 0, /* queue just allocated */
653 BFQQF_busy, /* has requests or is in service */
654 BFQQF_wait_request, /* waiting for a request */
655 BFQQF_non_blocking_wait_rq, /*
656 * waiting for a request
657 * without idling the device
658 */
659 BFQQF_fifo_expire, /* FIFO checked in this slice */
660 BFQQF_has_short_ttime, /* queue has a short think time */
661 BFQQF_sync, /* synchronous queue */
662 BFQQF_IO_bound, /*
663 * bfqq has timed-out at least once
664 * having consumed at most 2/10 of
665 * its budget
666 */
667 BFQQF_in_large_burst, /*
668 * bfqq activated in a large burst,
669 * see comments to bfq_handle_burst.
670 */
671 BFQQF_softrt_update, /*
672 * may need softrt-next-start
673 * update
674 */
675 BFQQF_coop, /* bfqq is shared */
676 BFQQF_split_coop /* shared bfqq will be split */
677};
678
679#define BFQ_BFQQ_FNS(name) \
680void bfq_mark_bfqq_##name(struct bfq_queue *bfqq); \
681void bfq_clear_bfqq_##name(struct bfq_queue *bfqq); \
682int bfq_bfqq_##name(const struct bfq_queue *bfqq);
683
684BFQ_BFQQ_FNS(just_created);
685BFQ_BFQQ_FNS(busy);
686BFQ_BFQQ_FNS(wait_request);
687BFQ_BFQQ_FNS(non_blocking_wait_rq);
688BFQ_BFQQ_FNS(fifo_expire);
689BFQ_BFQQ_FNS(has_short_ttime);
690BFQ_BFQQ_FNS(sync);
691BFQ_BFQQ_FNS(IO_bound);
692BFQ_BFQQ_FNS(in_large_burst);
693BFQ_BFQQ_FNS(coop);
694BFQ_BFQQ_FNS(split_coop);
695BFQ_BFQQ_FNS(softrt_update);
696#undef BFQ_BFQQ_FNS
697
698/* Expiration reasons. */
699enum bfqq_expiration {
700 BFQQE_TOO_IDLE = 0, /*
701 * queue has been idling for
702 * too long
703 */
704 BFQQE_BUDGET_TIMEOUT, /* budget took too long to be used */
705 BFQQE_BUDGET_EXHAUSTED, /* budget consumed */
706 BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */
707 BFQQE_PREEMPTED /* preemption in progress */
708};
709
710struct bfqg_stats {
711#if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
712 /* number of ios merged */
713 struct blkg_rwstat merged;
714 /* total time spent on device in ns, may not be accurate w/ queueing */
715 struct blkg_rwstat service_time;
716 /* total time spent waiting in scheduler queue in ns */
717 struct blkg_rwstat wait_time;
718 /* number of IOs queued up */
719 struct blkg_rwstat queued;
720 /* total disk time and nr sectors dispatched by this group */
721 struct blkg_stat time;
722 /* sum of number of ios queued across all samples */
723 struct blkg_stat avg_queue_size_sum;
724 /* count of samples taken for average */
725 struct blkg_stat avg_queue_size_samples;
726 /* how many times this group has been removed from service tree */
727 struct blkg_stat dequeue;
728 /* total time spent waiting for it to be assigned a timeslice. */
729 struct blkg_stat group_wait_time;
730 /* time spent idling for this blkcg_gq */
731 struct blkg_stat idle_time;
732 /* total time with empty current active q with other requests queued */
733 struct blkg_stat empty_time;
734 /* fields after this shouldn't be cleared on stat reset */
735 uint64_t start_group_wait_time;
736 uint64_t start_idle_time;
737 uint64_t start_empty_time;
738 uint16_t flags;
739#endif /* CONFIG_BFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
740};
741
742#ifdef CONFIG_BFQ_GROUP_IOSCHED
743
744/*
745 * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
746 *
747 * @ps: @blkcg_policy_storage that this structure inherits
748 * @weight: weight of the bfq_group
749 */
750struct bfq_group_data {
751 /* must be the first member */
752 struct blkcg_policy_data pd;
753
754 unsigned int weight;
755};
756
757/**
758 * struct bfq_group - per (device, cgroup) data structure.
759 * @entity: schedulable entity to insert into the parent group sched_data.
760 * @sched_data: own sched_data, to contain child entities (they may be
761 * both bfq_queues and bfq_groups).
762 * @bfqd: the bfq_data for the device this group acts upon.
763 * @async_bfqq: array of async queues for all the tasks belonging to
764 * the group, one queue per ioprio value per ioprio_class,
765 * except for the idle class that has only one queue.
766 * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
767 * @my_entity: pointer to @entity, %NULL for the toplevel group; used
768 * to avoid too many special cases during group creation/
769 * migration.
770 * @stats: stats for this bfqg.
771 * @active_entities: number of active entities belonging to the group;
772 * unused for the root group. Used to know whether there
773 * are groups with more than one active @bfq_entity
774 * (see the comments to the function
775 * bfq_bfqq_may_idle()).
776 * @rq_pos_tree: rbtree sorted by next_request position, used when
777 * determining if two or more queues have interleaving
778 * requests (see bfq_find_close_cooperator()).
779 *
780 * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
781 * there is a set of bfq_groups, each one collecting the lower-level
782 * entities belonging to the group that are acting on the same device.
783 *
784 * Locking works as follows:
785 * o @bfqd is protected by the queue lock, RCU is used to access it
786 * from the readers.
787 * o All the other fields are protected by the @bfqd queue lock.
788 */
789struct bfq_group {
790 /* must be the first member */
791 struct blkg_policy_data pd;
792
793 /* cached path for this blkg (see comments in bfq_bic_update_cgroup) */
794 char blkg_path[128];
795
796 /* reference counter (see comments in bfq_bic_update_cgroup) */
797 int ref;
798
799 struct bfq_entity entity;
800 struct bfq_sched_data sched_data;
801
802 void *bfqd;
803
804 struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
805 struct bfq_queue *async_idle_bfqq;
806
807 struct bfq_entity *my_entity;
808
809 int active_entities;
810
811 struct rb_root rq_pos_tree;
812
813 struct bfqg_stats stats;
814};
815
816#else
817struct bfq_group {
818 struct bfq_sched_data sched_data;
819
820 struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
821 struct bfq_queue *async_idle_bfqq;
822
823 struct rb_root rq_pos_tree;
824};
825#endif
826
827struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
828
829/* --------------- main algorithm interface ----------------- */
830
831#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \
832 { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
833
834extern const int bfq_timeout;
835
836struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync);
837void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync);
838struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);
839void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
840void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_entity *entity,
841 struct rb_root *root);
842void bfq_weights_tree_remove(struct bfq_data *bfqd, struct bfq_entity *entity,
843 struct rb_root *root);
844void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq,
845 bool compensate, enum bfqq_expiration reason);
846void bfq_put_queue(struct bfq_queue *bfqq);
847void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
848void bfq_schedule_dispatch(struct bfq_data *bfqd);
849void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
850
851/* ------------ end of main algorithm interface -------------- */
852
853/* ---------------- cgroups-support interface ---------------- */
854
855void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
856 unsigned int op);
857void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op);
858void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op);
859void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time,
860 uint64_t io_start_time, unsigned int op);
861void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
862void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
863void bfqg_stats_update_idle_time(struct bfq_group *bfqg);
864void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg);
865void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg);
866void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
867 struct bfq_group *bfqg);
868
869void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg);
870void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio);
871void bfq_end_wr_async(struct bfq_data *bfqd);
872struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
873 struct blkcg *blkcg);
874struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
875struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
876struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node);
877void bfqg_and_blkg_put(struct bfq_group *bfqg);
878
879#ifdef CONFIG_BFQ_GROUP_IOSCHED
880extern struct cftype bfq_blkcg_legacy_files[];
881extern struct cftype bfq_blkg_files[];
882extern struct blkcg_policy blkcg_policy_bfq;
883#endif
884
885/* ------------- end of cgroups-support interface ------------- */
886
887/* - interface of the internal hierarchical B-WF2Q+ scheduler - */
888
889#ifdef CONFIG_BFQ_GROUP_IOSCHED
890/* both next loops stop at one of the child entities of the root group */
891#define for_each_entity(entity) \
892 for (; entity ; entity = entity->parent)
893
894/*
895 * For each iteration, compute parent in advance, so as to be safe if
896 * entity is deallocated during the iteration. Such a deallocation may
897 * happen as a consequence of a bfq_put_queue that frees the bfq_queue
898 * containing entity.
899 */
900#define for_each_entity_safe(entity, parent) \
901 for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
902
903#else /* CONFIG_BFQ_GROUP_IOSCHED */
904/*
905 * Next two macros are fake loops when cgroups support is not
906 * enabled. I fact, in such a case, there is only one level to go up
907 * (to reach the root group).
908 */
909#define for_each_entity(entity) \
910 for (; entity ; entity = NULL)
911
912#define for_each_entity_safe(entity, parent) \
913 for (parent = NULL; entity ; entity = parent)
914#endif /* CONFIG_BFQ_GROUP_IOSCHED */
915
916struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq);
917struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
918struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);
919struct bfq_entity *bfq_entity_of(struct rb_node *node);
920unsigned short bfq_ioprio_to_weight(int ioprio);
921void bfq_put_idle_entity(struct bfq_service_tree *st,
922 struct bfq_entity *entity);
923struct bfq_service_tree *
924__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
925 struct bfq_entity *entity,
926 bool update_class_too);
927void bfq_bfqq_served(struct bfq_queue *bfqq, int served);
928void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
929 unsigned long time_ms);
930bool __bfq_deactivate_entity(struct bfq_entity *entity,
931 bool ins_into_idle_tree);
932bool next_queue_may_preempt(struct bfq_data *bfqd);
933struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd);
934void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd);
935void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
936 bool ins_into_idle_tree, bool expiration);
937void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
938void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
939 bool expiration);
940void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
941 bool expiration);
942void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq);
943
944/* --------------- end of interface of B-WF2Q+ ---------------- */
945
946/* Logging facilities. */
947#ifdef CONFIG_BFQ_GROUP_IOSCHED
948struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
949
950#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
951 blk_add_cgroup_trace_msg((bfqd)->queue, \
952 bfqg_to_blkg(bfqq_group(bfqq))->blkcg, \
953 "bfq%d%c " fmt, (bfqq)->pid, \
954 bfq_bfqq_sync((bfqq)) ? 'S' : 'A', ##args); \
955} while (0)
956
957#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \
958 blk_add_cgroup_trace_msg((bfqd)->queue, \
959 bfqg_to_blkg(bfqg)->blkcg, fmt, ##args); \
960} while (0)
961
962#else /* CONFIG_BFQ_GROUP_IOSCHED */
963
964#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \
965 blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid, \
966 bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \
967 ##args)
968#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0)
969
970#endif /* CONFIG_BFQ_GROUP_IOSCHED */
971
972#define bfq_log(bfqd, fmt, args...) \
973 blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
974
975#endif /* _BFQ_H */