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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * Header file for the BFQ I/O scheduler: data structures and
4 * prototypes of interface functions among BFQ components.
5 */
6#ifndef _BFQ_H
7#define _BFQ_H
8
9#include <linux/blktrace_api.h>
10#include <linux/hrtimer.h>
11#include <linux/blk-cgroup.h>
12
13#include "blk-cgroup-rwstat.h"
14
15#define BFQ_IOPRIO_CLASSES 3
16#define BFQ_CL_IDLE_TIMEOUT (HZ/5)
17
18#define BFQ_MIN_WEIGHT 1
19#define BFQ_MAX_WEIGHT 1000
20#define BFQ_WEIGHT_CONVERSION_COEFF 10
21
22#define BFQ_DEFAULT_QUEUE_IOPRIO 4
23
24#define BFQ_WEIGHT_LEGACY_DFL 100
25#define BFQ_DEFAULT_GRP_IOPRIO 0
26#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE
27
28#define MAX_PID_STR_LENGTH 12
29
30/*
31 * Soft real-time applications are extremely more latency sensitive
32 * than interactive ones. Over-raise the weight of the former to
33 * privilege them against the latter.
34 */
35#define BFQ_SOFTRT_WEIGHT_FACTOR 100
36
37struct bfq_entity;
38
39/**
40 * struct bfq_service_tree - per ioprio_class service tree.
41 *
42 * Each service tree represents a B-WF2Q+ scheduler on its own. Each
43 * ioprio_class has its own independent scheduler, and so its own
44 * bfq_service_tree. All the fields are protected by the queue lock
45 * of the containing bfqd.
46 */
47struct bfq_service_tree {
48 /* tree for active entities (i.e., those backlogged) */
49 struct rb_root active;
50 /* tree for idle entities (i.e., not backlogged, with V < F_i)*/
51 struct rb_root idle;
52
53 /* idle entity with minimum F_i */
54 struct bfq_entity *first_idle;
55 /* idle entity with maximum F_i */
56 struct bfq_entity *last_idle;
57
58 /* scheduler virtual time */
59 u64 vtime;
60 /* scheduler weight sum; active and idle entities contribute to it */
61 unsigned long wsum;
62};
63
64/**
65 * struct bfq_sched_data - multi-class scheduler.
66 *
67 * bfq_sched_data is the basic scheduler queue. It supports three
68 * ioprio_classes, and can be used either as a toplevel queue or as an
69 * intermediate queue in a hierarchical setup.
70 *
71 * The supported ioprio_classes are the same as in CFQ, in descending
72 * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
73 * Requests from higher priority queues are served before all the
74 * requests from lower priority queues; among requests of the same
75 * queue requests are served according to B-WF2Q+.
76 *
77 * The schedule is implemented by the service trees, plus the field
78 * @next_in_service, which points to the entity on the active trees
79 * that will be served next, if 1) no changes in the schedule occurs
80 * before the current in-service entity is expired, 2) the in-service
81 * queue becomes idle when it expires, and 3) if the entity pointed by
82 * in_service_entity is not a queue, then the in-service child entity
83 * of the entity pointed by in_service_entity becomes idle on
84 * expiration. This peculiar definition allows for the following
85 * optimization, not yet exploited: while a given entity is still in
86 * service, we already know which is the best candidate for next
87 * service among the other active entities in the same parent
88 * entity. We can then quickly compare the timestamps of the
89 * in-service entity with those of such best candidate.
90 *
91 * All fields are protected by the lock of the containing bfqd.
92 */
93struct bfq_sched_data {
94 /* entity in service */
95 struct bfq_entity *in_service_entity;
96 /* head-of-line entity (see comments above) */
97 struct bfq_entity *next_in_service;
98 /* array of service trees, one per ioprio_class */
99 struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
100 /* last time CLASS_IDLE was served */
101 unsigned long bfq_class_idle_last_service;
102
103};
104
105/**
106 * struct bfq_weight_counter - counter of the number of all active queues
107 * with a given weight.
108 */
109struct bfq_weight_counter {
110 unsigned int weight; /* weight of the queues this counter refers to */
111 unsigned int num_active; /* nr of active queues with this weight */
112 /*
113 * Weights tree member (see bfq_data's @queue_weights_tree)
114 */
115 struct rb_node weights_node;
116};
117
118/**
119 * struct bfq_entity - schedulable entity.
120 *
121 * A bfq_entity is used to represent either a bfq_queue (leaf node in the
122 * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each
123 * entity belongs to the sched_data of the parent group in the cgroup
124 * hierarchy. Non-leaf entities have also their own sched_data, stored
125 * in @my_sched_data.
126 *
127 * Each entity stores independently its priority values; this would
128 * allow different weights on different devices, but this
129 * functionality is not exported to userspace by now. Priorities and
130 * weights are updated lazily, first storing the new values into the
131 * new_* fields, then setting the @prio_changed flag. As soon as
132 * there is a transition in the entity state that allows the priority
133 * update to take place the effective and the requested priority
134 * values are synchronized.
135 *
136 * Unless cgroups are used, the weight value is calculated from the
137 * ioprio to export the same interface as CFQ. When dealing with
138 * "well-behaved" queues (i.e., queues that do not spend too much
139 * time to consume their budget and have true sequential behavior, and
140 * when there are no external factors breaking anticipation) the
141 * relative weights at each level of the cgroups hierarchy should be
142 * guaranteed. All the fields are protected by the queue lock of the
143 * containing bfqd.
144 */
145struct bfq_entity {
146 /* service_tree member */
147 struct rb_node rb_node;
148
149 /*
150 * Flag, true if the entity is on a tree (either the active or
151 * the idle one of its service_tree) or is in service.
152 */
153 bool on_st_or_in_serv;
154
155 /* B-WF2Q+ start and finish timestamps [sectors/weight] */
156 u64 start, finish;
157
158 /* tree the entity is enqueued into; %NULL if not on a tree */
159 struct rb_root *tree;
160
161 /*
162 * minimum start time of the (active) subtree rooted at this
163 * entity; used for O(log N) lookups into active trees
164 */
165 u64 min_start;
166
167 /* amount of service received during the last service slot */
168 int service;
169
170 /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
171 int budget;
172
173 /* device weight, if non-zero, it overrides the default weight of
174 * bfq_group_data */
175 int dev_weight;
176 /* weight of the queue */
177 int weight;
178 /* next weight if a change is in progress */
179 int new_weight;
180
181 /* original weight, used to implement weight boosting */
182 int orig_weight;
183
184 /* parent entity, for hierarchical scheduling */
185 struct bfq_entity *parent;
186
187 /*
188 * For non-leaf nodes in the hierarchy, the associated
189 * scheduler queue, %NULL on leaf nodes.
190 */
191 struct bfq_sched_data *my_sched_data;
192 /* the scheduler queue this entity belongs to */
193 struct bfq_sched_data *sched_data;
194
195 /* flag, set to request a weight, ioprio or ioprio_class change */
196 int prio_changed;
197
198 /* flag, set if the entity is counted in groups_with_pending_reqs */
199 bool in_groups_with_pending_reqs;
200};
201
202struct bfq_group;
203
204/**
205 * struct bfq_ttime - per process thinktime stats.
206 */
207struct bfq_ttime {
208 /* completion time of the last request */
209 u64 last_end_request;
210
211 /* total process thinktime */
212 u64 ttime_total;
213 /* number of thinktime samples */
214 unsigned long ttime_samples;
215 /* average process thinktime */
216 u64 ttime_mean;
217};
218
219/**
220 * struct bfq_queue - leaf schedulable entity.
221 *
222 * A bfq_queue is a leaf request queue; it can be associated with an
223 * io_context or more, if it is async or shared between cooperating
224 * processes. @cgroup holds a reference to the cgroup, to be sure that it
225 * does not disappear while a bfqq still references it (mostly to avoid
226 * races between request issuing and task migration followed by cgroup
227 * destruction).
228 * All the fields are protected by the queue lock of the containing bfqd.
229 */
230struct bfq_queue {
231 /* reference counter */
232 int ref;
233 /* parent bfq_data */
234 struct bfq_data *bfqd;
235
236 /* current ioprio and ioprio class */
237 unsigned short ioprio, ioprio_class;
238 /* next ioprio and ioprio class if a change is in progress */
239 unsigned short new_ioprio, new_ioprio_class;
240
241 /* last total-service-time sample, see bfq_update_inject_limit() */
242 u64 last_serv_time_ns;
243 /* limit for request injection */
244 unsigned int inject_limit;
245 /* last time the inject limit has been decreased, in jiffies */
246 unsigned long decrease_time_jif;
247
248 /*
249 * Shared bfq_queue if queue is cooperating with one or more
250 * other queues.
251 */
252 struct bfq_queue *new_bfqq;
253 /* request-position tree member (see bfq_group's @rq_pos_tree) */
254 struct rb_node pos_node;
255 /* request-position tree root (see bfq_group's @rq_pos_tree) */
256 struct rb_root *pos_root;
257
258 /* sorted list of pending requests */
259 struct rb_root sort_list;
260 /* if fifo isn't expired, next request to serve */
261 struct request *next_rq;
262 /* number of sync and async requests queued */
263 int queued[2];
264 /* number of requests currently allocated */
265 int allocated;
266 /* number of pending metadata requests */
267 int meta_pending;
268 /* fifo list of requests in sort_list */
269 struct list_head fifo;
270
271 /* entity representing this queue in the scheduler */
272 struct bfq_entity entity;
273
274 /* pointer to the weight counter associated with this entity */
275 struct bfq_weight_counter *weight_counter;
276
277 /* maximum budget allowed from the feedback mechanism */
278 int max_budget;
279 /* budget expiration (in jiffies) */
280 unsigned long budget_timeout;
281
282 /* number of requests on the dispatch list or inside driver */
283 int dispatched;
284
285 /* status flags */
286 unsigned long flags;
287
288 /* node for active/idle bfqq list inside parent bfqd */
289 struct list_head bfqq_list;
290
291 /* associated @bfq_ttime struct */
292 struct bfq_ttime ttime;
293
294 /* bit vector: a 1 for each seeky requests in history */
295 u32 seek_history;
296
297 /* node for the device's burst list */
298 struct hlist_node burst_list_node;
299
300 /* position of the last request enqueued */
301 sector_t last_request_pos;
302
303 /* Number of consecutive pairs of request completion and
304 * arrival, such that the queue becomes idle after the
305 * completion, but the next request arrives within an idle
306 * time slice; used only if the queue's IO_bound flag has been
307 * cleared.
308 */
309 unsigned int requests_within_timer;
310
311 /* pid of the process owning the queue, used for logging purposes */
312 pid_t pid;
313
314 /*
315 * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
316 * if the queue is shared.
317 */
318 struct bfq_io_cq *bic;
319
320 /* current maximum weight-raising time for this queue */
321 unsigned long wr_cur_max_time;
322 /*
323 * Minimum time instant such that, only if a new request is
324 * enqueued after this time instant in an idle @bfq_queue with
325 * no outstanding requests, then the task associated with the
326 * queue it is deemed as soft real-time (see the comments on
327 * the function bfq_bfqq_softrt_next_start())
328 */
329 unsigned long soft_rt_next_start;
330 /*
331 * Start time of the current weight-raising period if
332 * the @bfq-queue is being weight-raised, otherwise
333 * finish time of the last weight-raising period.
334 */
335 unsigned long last_wr_start_finish;
336 /* factor by which the weight of this queue is multiplied */
337 unsigned int wr_coeff;
338 /*
339 * Time of the last transition of the @bfq_queue from idle to
340 * backlogged.
341 */
342 unsigned long last_idle_bklogged;
343 /*
344 * Cumulative service received from the @bfq_queue since the
345 * last transition from idle to backlogged.
346 */
347 unsigned long service_from_backlogged;
348 /*
349 * Cumulative service received from the @bfq_queue since its
350 * last transition to weight-raised state.
351 */
352 unsigned long service_from_wr;
353
354 /*
355 * Value of wr start time when switching to soft rt
356 */
357 unsigned long wr_start_at_switch_to_srt;
358
359 unsigned long split_time; /* time of last split */
360
361 unsigned long first_IO_time; /* time of first I/O for this queue */
362
363 /* max service rate measured so far */
364 u32 max_service_rate;
365
366 /*
367 * Pointer to the waker queue for this queue, i.e., to the
368 * queue Q such that this queue happens to get new I/O right
369 * after some I/O request of Q is completed. For details, see
370 * the comments on the choice of the queue for injection in
371 * bfq_select_queue().
372 */
373 struct bfq_queue *waker_bfqq;
374 /* node for woken_list, see below */
375 struct hlist_node woken_list_node;
376 /*
377 * Head of the list of the woken queues for this queue, i.e.,
378 * of the list of the queues for which this queue is a waker
379 * queue. This list is used to reset the waker_bfqq pointer in
380 * the woken queues when this queue exits.
381 */
382 struct hlist_head woken_list;
383};
384
385/**
386 * struct bfq_io_cq - per (request_queue, io_context) structure.
387 */
388struct bfq_io_cq {
389 /* associated io_cq structure */
390 struct io_cq icq; /* must be the first member */
391 /* array of two process queues, the sync and the async */
392 struct bfq_queue *bfqq[2];
393 /* per (request_queue, blkcg) ioprio */
394 int ioprio;
395#ifdef CONFIG_BFQ_GROUP_IOSCHED
396 uint64_t blkcg_serial_nr; /* the current blkcg serial */
397#endif
398 /*
399 * Snapshot of the has_short_time flag before merging; taken
400 * to remember its value while the queue is merged, so as to
401 * be able to restore it in case of split.
402 */
403 bool saved_has_short_ttime;
404 /*
405 * Same purpose as the previous two fields for the I/O bound
406 * classification of a queue.
407 */
408 bool saved_IO_bound;
409
410 /*
411 * Same purpose as the previous fields for the value of the
412 * field keeping the queue's belonging to a large burst
413 */
414 bool saved_in_large_burst;
415 /*
416 * True if the queue belonged to a burst list before its merge
417 * with another cooperating queue.
418 */
419 bool was_in_burst_list;
420
421 /*
422 * Save the weight when a merge occurs, to be able
423 * to restore it in case of split. If the weight is not
424 * correctly resumed when the queue is recycled,
425 * then the weight of the recycled queue could differ
426 * from the weight of the original queue.
427 */
428 unsigned int saved_weight;
429
430 /*
431 * Similar to previous fields: save wr information.
432 */
433 unsigned long saved_wr_coeff;
434 unsigned long saved_last_wr_start_finish;
435 unsigned long saved_wr_start_at_switch_to_srt;
436 unsigned int saved_wr_cur_max_time;
437 struct bfq_ttime saved_ttime;
438};
439
440/**
441 * struct bfq_data - per-device data structure.
442 *
443 * All the fields are protected by @lock.
444 */
445struct bfq_data {
446 /* device request queue */
447 struct request_queue *queue;
448 /* dispatch queue */
449 struct list_head dispatch;
450
451 /* root bfq_group for the device */
452 struct bfq_group *root_group;
453
454 /*
455 * rbtree of weight counters of @bfq_queues, sorted by
456 * weight. Used to keep track of whether all @bfq_queues have
457 * the same weight. The tree contains one counter for each
458 * distinct weight associated to some active and not
459 * weight-raised @bfq_queue (see the comments to the functions
460 * bfq_weights_tree_[add|remove] for further details).
461 */
462 struct rb_root_cached queue_weights_tree;
463
464 /*
465 * Number of groups with at least one descendant process that
466 * has at least one request waiting for completion. Note that
467 * this accounts for also requests already dispatched, but not
468 * yet completed. Therefore this number of groups may differ
469 * (be larger) than the number of active groups, as a group is
470 * considered active only if its corresponding entity has
471 * descendant queues with at least one request queued. This
472 * number is used to decide whether a scenario is symmetric.
473 * For a detailed explanation see comments on the computation
474 * of the variable asymmetric_scenario in the function
475 * bfq_better_to_idle().
476 *
477 * However, it is hard to compute this number exactly, for
478 * groups with multiple descendant processes. Consider a group
479 * that is inactive, i.e., that has no descendant process with
480 * pending I/O inside BFQ queues. Then suppose that
481 * num_groups_with_pending_reqs is still accounting for this
482 * group, because the group has descendant processes with some
483 * I/O request still in flight. num_groups_with_pending_reqs
484 * should be decremented when the in-flight request of the
485 * last descendant process is finally completed (assuming that
486 * nothing else has changed for the group in the meantime, in
487 * terms of composition of the group and active/inactive state of child
488 * groups and processes). To accomplish this, an additional
489 * pending-request counter must be added to entities, and must
490 * be updated correctly. To avoid this additional field and operations,
491 * we resort to the following tradeoff between simplicity and
492 * accuracy: for an inactive group that is still counted in
493 * num_groups_with_pending_reqs, we decrement
494 * num_groups_with_pending_reqs when the first descendant
495 * process of the group remains with no request waiting for
496 * completion.
497 *
498 * Even this simpler decrement strategy requires a little
499 * carefulness: to avoid multiple decrements, we flag a group,
500 * more precisely an entity representing a group, as still
501 * counted in num_groups_with_pending_reqs when it becomes
502 * inactive. Then, when the first descendant queue of the
503 * entity remains with no request waiting for completion,
504 * num_groups_with_pending_reqs is decremented, and this flag
505 * is reset. After this flag is reset for the entity,
506 * num_groups_with_pending_reqs won't be decremented any
507 * longer in case a new descendant queue of the entity remains
508 * with no request waiting for completion.
509 */
510 unsigned int num_groups_with_pending_reqs;
511
512 /*
513 * Per-class (RT, BE, IDLE) number of bfq_queues containing
514 * requests (including the queue in service, even if it is
515 * idling).
516 */
517 unsigned int busy_queues[3];
518 /* number of weight-raised busy @bfq_queues */
519 int wr_busy_queues;
520 /* number of queued requests */
521 int queued;
522 /* number of requests dispatched and waiting for completion */
523 int rq_in_driver;
524
525 /* true if the device is non rotational and performs queueing */
526 bool nonrot_with_queueing;
527
528 /*
529 * Maximum number of requests in driver in the last
530 * @hw_tag_samples completed requests.
531 */
532 int max_rq_in_driver;
533 /* number of samples used to calculate hw_tag */
534 int hw_tag_samples;
535 /* flag set to one if the driver is showing a queueing behavior */
536 int hw_tag;
537
538 /* number of budgets assigned */
539 int budgets_assigned;
540
541 /*
542 * Timer set when idling (waiting) for the next request from
543 * the queue in service.
544 */
545 struct hrtimer idle_slice_timer;
546
547 /* bfq_queue in service */
548 struct bfq_queue *in_service_queue;
549
550 /* on-disk position of the last served request */
551 sector_t last_position;
552
553 /* position of the last served request for the in-service queue */
554 sector_t in_serv_last_pos;
555
556 /* time of last request completion (ns) */
557 u64 last_completion;
558
559 /* bfqq owning the last completed rq */
560 struct bfq_queue *last_completed_rq_bfqq;
561
562 /* time of last transition from empty to non-empty (ns) */
563 u64 last_empty_occupied_ns;
564
565 /*
566 * Flag set to activate the sampling of the total service time
567 * of a just-arrived first I/O request (see
568 * bfq_update_inject_limit()). This will cause the setting of
569 * waited_rq when the request is finally dispatched.
570 */
571 bool wait_dispatch;
572 /*
573 * If set, then bfq_update_inject_limit() is invoked when
574 * waited_rq is eventually completed.
575 */
576 struct request *waited_rq;
577 /*
578 * True if some request has been injected during the last service hole.
579 */
580 bool rqs_injected;
581
582 /* time of first rq dispatch in current observation interval (ns) */
583 u64 first_dispatch;
584 /* time of last rq dispatch in current observation interval (ns) */
585 u64 last_dispatch;
586
587 /* beginning of the last budget */
588 ktime_t last_budget_start;
589 /* beginning of the last idle slice */
590 ktime_t last_idling_start;
591 unsigned long last_idling_start_jiffies;
592
593 /* number of samples in current observation interval */
594 int peak_rate_samples;
595 /* num of samples of seq dispatches in current observation interval */
596 u32 sequential_samples;
597 /* total num of sectors transferred in current observation interval */
598 u64 tot_sectors_dispatched;
599 /* max rq size seen during current observation interval (sectors) */
600 u32 last_rq_max_size;
601 /* time elapsed from first dispatch in current observ. interval (us) */
602 u64 delta_from_first;
603 /*
604 * Current estimate of the device peak rate, measured in
605 * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by
606 * BFQ_RATE_SHIFT is performed to increase precision in
607 * fixed-point calculations.
608 */
609 u32 peak_rate;
610
611 /* maximum budget allotted to a bfq_queue before rescheduling */
612 int bfq_max_budget;
613
614 /* list of all the bfq_queues active on the device */
615 struct list_head active_list;
616 /* list of all the bfq_queues idle on the device */
617 struct list_head idle_list;
618
619 /*
620 * Timeout for async/sync requests; when it fires, requests
621 * are served in fifo order.
622 */
623 u64 bfq_fifo_expire[2];
624 /* weight of backward seeks wrt forward ones */
625 unsigned int bfq_back_penalty;
626 /* maximum allowed backward seek */
627 unsigned int bfq_back_max;
628 /* maximum idling time */
629 u32 bfq_slice_idle;
630
631 /* user-configured max budget value (0 for auto-tuning) */
632 int bfq_user_max_budget;
633 /*
634 * Timeout for bfq_queues to consume their budget; used to
635 * prevent seeky queues from imposing long latencies to
636 * sequential or quasi-sequential ones (this also implies that
637 * seeky queues cannot receive guarantees in the service
638 * domain; after a timeout they are charged for the time they
639 * have been in service, to preserve fairness among them, but
640 * without service-domain guarantees).
641 */
642 unsigned int bfq_timeout;
643
644 /*
645 * Number of consecutive requests that must be issued within
646 * the idle time slice to set again idling to a queue which
647 * was marked as non-I/O-bound (see the definition of the
648 * IO_bound flag for further details).
649 */
650 unsigned int bfq_requests_within_timer;
651
652 /*
653 * Force device idling whenever needed to provide accurate
654 * service guarantees, without caring about throughput
655 * issues. CAVEAT: this may even increase latencies, in case
656 * of useless idling for processes that did stop doing I/O.
657 */
658 bool strict_guarantees;
659
660 /*
661 * Last time at which a queue entered the current burst of
662 * queues being activated shortly after each other; for more
663 * details about this and the following parameters related to
664 * a burst of activations, see the comments on the function
665 * bfq_handle_burst.
666 */
667 unsigned long last_ins_in_burst;
668 /*
669 * Reference time interval used to decide whether a queue has
670 * been activated shortly after @last_ins_in_burst.
671 */
672 unsigned long bfq_burst_interval;
673 /* number of queues in the current burst of queue activations */
674 int burst_size;
675
676 /* common parent entity for the queues in the burst */
677 struct bfq_entity *burst_parent_entity;
678 /* Maximum burst size above which the current queue-activation
679 * burst is deemed as 'large'.
680 */
681 unsigned long bfq_large_burst_thresh;
682 /* true if a large queue-activation burst is in progress */
683 bool large_burst;
684 /*
685 * Head of the burst list (as for the above fields, more
686 * details in the comments on the function bfq_handle_burst).
687 */
688 struct hlist_head burst_list;
689
690 /* if set to true, low-latency heuristics are enabled */
691 bool low_latency;
692 /*
693 * Maximum factor by which the weight of a weight-raised queue
694 * is multiplied.
695 */
696 unsigned int bfq_wr_coeff;
697 /* maximum duration of a weight-raising period (jiffies) */
698 unsigned int bfq_wr_max_time;
699
700 /* Maximum weight-raising duration for soft real-time processes */
701 unsigned int bfq_wr_rt_max_time;
702 /*
703 * Minimum idle period after which weight-raising may be
704 * reactivated for a queue (in jiffies).
705 */
706 unsigned int bfq_wr_min_idle_time;
707 /*
708 * Minimum period between request arrivals after which
709 * weight-raising may be reactivated for an already busy async
710 * queue (in jiffies).
711 */
712 unsigned long bfq_wr_min_inter_arr_async;
713
714 /* Max service-rate for a soft real-time queue, in sectors/sec */
715 unsigned int bfq_wr_max_softrt_rate;
716 /*
717 * Cached value of the product ref_rate*ref_wr_duration, used
718 * for computing the maximum duration of weight raising
719 * automatically.
720 */
721 u64 rate_dur_prod;
722
723 /* fallback dummy bfqq for extreme OOM conditions */
724 struct bfq_queue oom_bfqq;
725
726 spinlock_t lock;
727
728 /*
729 * bic associated with the task issuing current bio for
730 * merging. This and the next field are used as a support to
731 * be able to perform the bic lookup, needed by bio-merge
732 * functions, before the scheduler lock is taken, and thus
733 * avoid taking the request-queue lock while the scheduler
734 * lock is being held.
735 */
736 struct bfq_io_cq *bio_bic;
737 /* bfqq associated with the task issuing current bio for merging */
738 struct bfq_queue *bio_bfqq;
739
740 /*
741 * Depth limits used in bfq_limit_depth (see comments on the
742 * function)
743 */
744 unsigned int word_depths[2][2];
745};
746
747enum bfqq_state_flags {
748 BFQQF_just_created = 0, /* queue just allocated */
749 BFQQF_busy, /* has requests or is in service */
750 BFQQF_wait_request, /* waiting for a request */
751 BFQQF_non_blocking_wait_rq, /*
752 * waiting for a request
753 * without idling the device
754 */
755 BFQQF_fifo_expire, /* FIFO checked in this slice */
756 BFQQF_has_short_ttime, /* queue has a short think time */
757 BFQQF_sync, /* synchronous queue */
758 BFQQF_IO_bound, /*
759 * bfqq has timed-out at least once
760 * having consumed at most 2/10 of
761 * its budget
762 */
763 BFQQF_in_large_burst, /*
764 * bfqq activated in a large burst,
765 * see comments to bfq_handle_burst.
766 */
767 BFQQF_softrt_update, /*
768 * may need softrt-next-start
769 * update
770 */
771 BFQQF_coop, /* bfqq is shared */
772 BFQQF_split_coop, /* shared bfqq will be split */
773 BFQQF_has_waker /* bfqq has a waker queue */
774};
775
776#define BFQ_BFQQ_FNS(name) \
777void bfq_mark_bfqq_##name(struct bfq_queue *bfqq); \
778void bfq_clear_bfqq_##name(struct bfq_queue *bfqq); \
779int bfq_bfqq_##name(const struct bfq_queue *bfqq);
780
781BFQ_BFQQ_FNS(just_created);
782BFQ_BFQQ_FNS(busy);
783BFQ_BFQQ_FNS(wait_request);
784BFQ_BFQQ_FNS(non_blocking_wait_rq);
785BFQ_BFQQ_FNS(fifo_expire);
786BFQ_BFQQ_FNS(has_short_ttime);
787BFQ_BFQQ_FNS(sync);
788BFQ_BFQQ_FNS(IO_bound);
789BFQ_BFQQ_FNS(in_large_burst);
790BFQ_BFQQ_FNS(coop);
791BFQ_BFQQ_FNS(split_coop);
792BFQ_BFQQ_FNS(softrt_update);
793BFQ_BFQQ_FNS(has_waker);
794#undef BFQ_BFQQ_FNS
795
796/* Expiration reasons. */
797enum bfqq_expiration {
798 BFQQE_TOO_IDLE = 0, /*
799 * queue has been idling for
800 * too long
801 */
802 BFQQE_BUDGET_TIMEOUT, /* budget took too long to be used */
803 BFQQE_BUDGET_EXHAUSTED, /* budget consumed */
804 BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */
805 BFQQE_PREEMPTED /* preemption in progress */
806};
807
808struct bfq_stat {
809 struct percpu_counter cpu_cnt;
810 atomic64_t aux_cnt;
811};
812
813struct bfqg_stats {
814 /* basic stats */
815 struct blkg_rwstat bytes;
816 struct blkg_rwstat ios;
817#ifdef CONFIG_BFQ_CGROUP_DEBUG
818 /* number of ios merged */
819 struct blkg_rwstat merged;
820 /* total time spent on device in ns, may not be accurate w/ queueing */
821 struct blkg_rwstat service_time;
822 /* total time spent waiting in scheduler queue in ns */
823 struct blkg_rwstat wait_time;
824 /* number of IOs queued up */
825 struct blkg_rwstat queued;
826 /* total disk time and nr sectors dispatched by this group */
827 struct bfq_stat time;
828 /* sum of number of ios queued across all samples */
829 struct bfq_stat avg_queue_size_sum;
830 /* count of samples taken for average */
831 struct bfq_stat avg_queue_size_samples;
832 /* how many times this group has been removed from service tree */
833 struct bfq_stat dequeue;
834 /* total time spent waiting for it to be assigned a timeslice. */
835 struct bfq_stat group_wait_time;
836 /* time spent idling for this blkcg_gq */
837 struct bfq_stat idle_time;
838 /* total time with empty current active q with other requests queued */
839 struct bfq_stat empty_time;
840 /* fields after this shouldn't be cleared on stat reset */
841 u64 start_group_wait_time;
842 u64 start_idle_time;
843 u64 start_empty_time;
844 uint16_t flags;
845#endif /* CONFIG_BFQ_CGROUP_DEBUG */
846};
847
848#ifdef CONFIG_BFQ_GROUP_IOSCHED
849
850/*
851 * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
852 *
853 * @ps: @blkcg_policy_storage that this structure inherits
854 * @weight: weight of the bfq_group
855 */
856struct bfq_group_data {
857 /* must be the first member */
858 struct blkcg_policy_data pd;
859
860 unsigned int weight;
861};
862
863/**
864 * struct bfq_group - per (device, cgroup) data structure.
865 * @entity: schedulable entity to insert into the parent group sched_data.
866 * @sched_data: own sched_data, to contain child entities (they may be
867 * both bfq_queues and bfq_groups).
868 * @bfqd: the bfq_data for the device this group acts upon.
869 * @async_bfqq: array of async queues for all the tasks belonging to
870 * the group, one queue per ioprio value per ioprio_class,
871 * except for the idle class that has only one queue.
872 * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
873 * @my_entity: pointer to @entity, %NULL for the toplevel group; used
874 * to avoid too many special cases during group creation/
875 * migration.
876 * @stats: stats for this bfqg.
877 * @active_entities: number of active entities belonging to the group;
878 * unused for the root group. Used to know whether there
879 * are groups with more than one active @bfq_entity
880 * (see the comments to the function
881 * bfq_bfqq_may_idle()).
882 * @rq_pos_tree: rbtree sorted by next_request position, used when
883 * determining if two or more queues have interleaving
884 * requests (see bfq_find_close_cooperator()).
885 *
886 * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
887 * there is a set of bfq_groups, each one collecting the lower-level
888 * entities belonging to the group that are acting on the same device.
889 *
890 * Locking works as follows:
891 * o @bfqd is protected by the queue lock, RCU is used to access it
892 * from the readers.
893 * o All the other fields are protected by the @bfqd queue lock.
894 */
895struct bfq_group {
896 /* must be the first member */
897 struct blkg_policy_data pd;
898
899 /* cached path for this blkg (see comments in bfq_bic_update_cgroup) */
900 char blkg_path[128];
901
902 /* reference counter (see comments in bfq_bic_update_cgroup) */
903 int ref;
904
905 struct bfq_entity entity;
906 struct bfq_sched_data sched_data;
907
908 void *bfqd;
909
910 struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
911 struct bfq_queue *async_idle_bfqq;
912
913 struct bfq_entity *my_entity;
914
915 int active_entities;
916
917 struct rb_root rq_pos_tree;
918
919 struct bfqg_stats stats;
920};
921
922#else
923struct bfq_group {
924 struct bfq_entity entity;
925 struct bfq_sched_data sched_data;
926
927 struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
928 struct bfq_queue *async_idle_bfqq;
929
930 struct rb_root rq_pos_tree;
931};
932#endif
933
934struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
935
936/* --------------- main algorithm interface ----------------- */
937
938#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \
939 { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
940
941extern const int bfq_timeout;
942
943struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync);
944void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync);
945struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);
946void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
947void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq,
948 struct rb_root_cached *root);
949void __bfq_weights_tree_remove(struct bfq_data *bfqd,
950 struct bfq_queue *bfqq,
951 struct rb_root_cached *root);
952void bfq_weights_tree_remove(struct bfq_data *bfqd,
953 struct bfq_queue *bfqq);
954void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq,
955 bool compensate, enum bfqq_expiration reason);
956void bfq_put_queue(struct bfq_queue *bfqq);
957void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
958void bfq_release_process_ref(struct bfq_data *bfqd, struct bfq_queue *bfqq);
959void bfq_schedule_dispatch(struct bfq_data *bfqd);
960void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
961
962/* ------------ end of main algorithm interface -------------- */
963
964/* ---------------- cgroups-support interface ---------------- */
965
966void bfqg_stats_update_legacy_io(struct request_queue *q, struct request *rq);
967void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
968 unsigned int op);
969void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op);
970void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op);
971void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
972 u64 io_start_time_ns, unsigned int op);
973void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
974void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
975void bfqg_stats_update_idle_time(struct bfq_group *bfqg);
976void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg);
977void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg);
978void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
979 struct bfq_group *bfqg);
980
981void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg);
982void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio);
983void bfq_end_wr_async(struct bfq_data *bfqd);
984struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
985 struct blkcg *blkcg);
986struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
987struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
988struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node);
989void bfqg_and_blkg_put(struct bfq_group *bfqg);
990
991#ifdef CONFIG_BFQ_GROUP_IOSCHED
992extern struct cftype bfq_blkcg_legacy_files[];
993extern struct cftype bfq_blkg_files[];
994extern struct blkcg_policy blkcg_policy_bfq;
995#endif
996
997/* ------------- end of cgroups-support interface ------------- */
998
999/* - interface of the internal hierarchical B-WF2Q+ scheduler - */
1000
1001#ifdef CONFIG_BFQ_GROUP_IOSCHED
1002/* both next loops stop at one of the child entities of the root group */
1003#define for_each_entity(entity) \
1004 for (; entity ; entity = entity->parent)
1005
1006/*
1007 * For each iteration, compute parent in advance, so as to be safe if
1008 * entity is deallocated during the iteration. Such a deallocation may
1009 * happen as a consequence of a bfq_put_queue that frees the bfq_queue
1010 * containing entity.
1011 */
1012#define for_each_entity_safe(entity, parent) \
1013 for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
1014
1015#else /* CONFIG_BFQ_GROUP_IOSCHED */
1016/*
1017 * Next two macros are fake loops when cgroups support is not
1018 * enabled. I fact, in such a case, there is only one level to go up
1019 * (to reach the root group).
1020 */
1021#define for_each_entity(entity) \
1022 for (; entity ; entity = NULL)
1023
1024#define for_each_entity_safe(entity, parent) \
1025 for (parent = NULL; entity ; entity = parent)
1026#endif /* CONFIG_BFQ_GROUP_IOSCHED */
1027
1028struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq);
1029struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
1030unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd);
1031struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);
1032struct bfq_entity *bfq_entity_of(struct rb_node *node);
1033unsigned short bfq_ioprio_to_weight(int ioprio);
1034void bfq_put_idle_entity(struct bfq_service_tree *st,
1035 struct bfq_entity *entity);
1036struct bfq_service_tree *
1037__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
1038 struct bfq_entity *entity,
1039 bool update_class_too);
1040void bfq_bfqq_served(struct bfq_queue *bfqq, int served);
1041void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1042 unsigned long time_ms);
1043bool __bfq_deactivate_entity(struct bfq_entity *entity,
1044 bool ins_into_idle_tree);
1045bool next_queue_may_preempt(struct bfq_data *bfqd);
1046struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd);
1047bool __bfq_bfqd_reset_in_service(struct bfq_data *bfqd);
1048void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1049 bool ins_into_idle_tree, bool expiration);
1050void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
1051void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1052 bool expiration);
1053void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1054 bool expiration);
1055void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq);
1056
1057/* --------------- end of interface of B-WF2Q+ ---------------- */
1058
1059/* Logging facilities. */
1060static inline void bfq_pid_to_str(int pid, char *str, int len)
1061{
1062 if (pid != -1)
1063 snprintf(str, len, "%d", pid);
1064 else
1065 snprintf(str, len, "SHARED-");
1066}
1067
1068#ifdef CONFIG_BFQ_GROUP_IOSCHED
1069struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
1070
1071#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
1072 char pid_str[MAX_PID_STR_LENGTH]; \
1073 if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \
1074 break; \
1075 bfq_pid_to_str((bfqq)->pid, pid_str, MAX_PID_STR_LENGTH); \
1076 blk_add_cgroup_trace_msg((bfqd)->queue, \
1077 bfqg_to_blkg(bfqq_group(bfqq))->blkcg, \
1078 "bfq%s%c " fmt, pid_str, \
1079 bfq_bfqq_sync((bfqq)) ? 'S' : 'A', ##args); \
1080} while (0)
1081
1082#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \
1083 blk_add_cgroup_trace_msg((bfqd)->queue, \
1084 bfqg_to_blkg(bfqg)->blkcg, fmt, ##args); \
1085} while (0)
1086
1087#else /* CONFIG_BFQ_GROUP_IOSCHED */
1088
1089#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
1090 char pid_str[MAX_PID_STR_LENGTH]; \
1091 if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \
1092 break; \
1093 bfq_pid_to_str((bfqq)->pid, pid_str, MAX_PID_STR_LENGTH); \
1094 blk_add_trace_msg((bfqd)->queue, "bfq%s%c " fmt, pid_str, \
1095 bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \
1096 ##args); \
1097} while (0)
1098#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0)
1099
1100#endif /* CONFIG_BFQ_GROUP_IOSCHED */
1101
1102#define bfq_log(bfqd, fmt, args...) \
1103 blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
1104
1105#endif /* _BFQ_H */