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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 /* last child queue of entity created (for non-leaf entities) */
202 struct bfq_queue *last_bfqq_created;
203};
204
205struct bfq_group;
206
207/**
208 * struct bfq_ttime - per process thinktime stats.
209 */
210struct bfq_ttime {
211 /* completion time of the last request */
212 u64 last_end_request;
213
214 /* total process thinktime */
215 u64 ttime_total;
216 /* number of thinktime samples */
217 unsigned long ttime_samples;
218 /* average process thinktime */
219 u64 ttime_mean;
220};
221
222/**
223 * struct bfq_queue - leaf schedulable entity.
224 *
225 * A bfq_queue is a leaf request queue; it can be associated with an
226 * io_context or more, if it is async or shared between cooperating
227 * processes. @cgroup holds a reference to the cgroup, to be sure that it
228 * does not disappear while a bfqq still references it (mostly to avoid
229 * races between request issuing and task migration followed by cgroup
230 * destruction).
231 * All the fields are protected by the queue lock of the containing bfqd.
232 */
233struct bfq_queue {
234 /* reference counter */
235 int ref;
236 /* counter of references from other queues for delayed stable merge */
237 int stable_ref;
238 /* parent bfq_data */
239 struct bfq_data *bfqd;
240
241 /* current ioprio and ioprio class */
242 unsigned short ioprio, ioprio_class;
243 /* next ioprio and ioprio class if a change is in progress */
244 unsigned short new_ioprio, new_ioprio_class;
245
246 /* last total-service-time sample, see bfq_update_inject_limit() */
247 u64 last_serv_time_ns;
248 /* limit for request injection */
249 unsigned int inject_limit;
250 /* last time the inject limit has been decreased, in jiffies */
251 unsigned long decrease_time_jif;
252
253 /*
254 * Shared bfq_queue if queue is cooperating with one or more
255 * other queues.
256 */
257 struct bfq_queue *new_bfqq;
258 /* request-position tree member (see bfq_group's @rq_pos_tree) */
259 struct rb_node pos_node;
260 /* request-position tree root (see bfq_group's @rq_pos_tree) */
261 struct rb_root *pos_root;
262
263 /* sorted list of pending requests */
264 struct rb_root sort_list;
265 /* if fifo isn't expired, next request to serve */
266 struct request *next_rq;
267 /* number of sync and async requests queued */
268 int queued[2];
269 /* number of requests currently allocated */
270 int allocated;
271 /* number of pending metadata requests */
272 int meta_pending;
273 /* fifo list of requests in sort_list */
274 struct list_head fifo;
275
276 /* entity representing this queue in the scheduler */
277 struct bfq_entity entity;
278
279 /* pointer to the weight counter associated with this entity */
280 struct bfq_weight_counter *weight_counter;
281
282 /* maximum budget allowed from the feedback mechanism */
283 int max_budget;
284 /* budget expiration (in jiffies) */
285 unsigned long budget_timeout;
286
287 /* number of requests on the dispatch list or inside driver */
288 int dispatched;
289
290 /* status flags */
291 unsigned long flags;
292
293 /* node for active/idle bfqq list inside parent bfqd */
294 struct list_head bfqq_list;
295
296 /* associated @bfq_ttime struct */
297 struct bfq_ttime ttime;
298
299 /* when bfqq started to do I/O within the last observation window */
300 u64 io_start_time;
301 /* how long bfqq has remained empty during the last observ. window */
302 u64 tot_idle_time;
303
304 /* bit vector: a 1 for each seeky requests in history */
305 u32 seek_history;
306
307 /* node for the device's burst list */
308 struct hlist_node burst_list_node;
309
310 /* position of the last request enqueued */
311 sector_t last_request_pos;
312
313 /* Number of consecutive pairs of request completion and
314 * arrival, such that the queue becomes idle after the
315 * completion, but the next request arrives within an idle
316 * time slice; used only if the queue's IO_bound flag has been
317 * cleared.
318 */
319 unsigned int requests_within_timer;
320
321 /* pid of the process owning the queue, used for logging purposes */
322 pid_t pid;
323
324 /*
325 * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
326 * if the queue is shared.
327 */
328 struct bfq_io_cq *bic;
329
330 /* current maximum weight-raising time for this queue */
331 unsigned long wr_cur_max_time;
332 /*
333 * Minimum time instant such that, only if a new request is
334 * enqueued after this time instant in an idle @bfq_queue with
335 * no outstanding requests, then the task associated with the
336 * queue it is deemed as soft real-time (see the comments on
337 * the function bfq_bfqq_softrt_next_start())
338 */
339 unsigned long soft_rt_next_start;
340 /*
341 * Start time of the current weight-raising period if
342 * the @bfq-queue is being weight-raised, otherwise
343 * finish time of the last weight-raising period.
344 */
345 unsigned long last_wr_start_finish;
346 /* factor by which the weight of this queue is multiplied */
347 unsigned int wr_coeff;
348 /*
349 * Time of the last transition of the @bfq_queue from idle to
350 * backlogged.
351 */
352 unsigned long last_idle_bklogged;
353 /*
354 * Cumulative service received from the @bfq_queue since the
355 * last transition from idle to backlogged.
356 */
357 unsigned long service_from_backlogged;
358 /*
359 * Cumulative service received from the @bfq_queue since its
360 * last transition to weight-raised state.
361 */
362 unsigned long service_from_wr;
363
364 /*
365 * Value of wr start time when switching to soft rt
366 */
367 unsigned long wr_start_at_switch_to_srt;
368
369 unsigned long split_time; /* time of last split */
370
371 unsigned long first_IO_time; /* time of first I/O for this queue */
372
373 unsigned long creation_time; /* when this queue is created */
374
375 /* max service rate measured so far */
376 u32 max_service_rate;
377
378 /*
379 * Pointer to the waker queue for this queue, i.e., to the
380 * queue Q such that this queue happens to get new I/O right
381 * after some I/O request of Q is completed. For details, see
382 * the comments on the choice of the queue for injection in
383 * bfq_select_queue().
384 */
385 struct bfq_queue *waker_bfqq;
386 /* pointer to the curr. tentative waker queue, see bfq_check_waker() */
387 struct bfq_queue *tentative_waker_bfqq;
388 /* number of times the same tentative waker has been detected */
389 unsigned int num_waker_detections;
390
391 /* node for woken_list, see below */
392 struct hlist_node woken_list_node;
393 /*
394 * Head of the list of the woken queues for this queue, i.e.,
395 * of the list of the queues for which this queue is a waker
396 * queue. This list is used to reset the waker_bfqq pointer in
397 * the woken queues when this queue exits.
398 */
399 struct hlist_head woken_list;
400};
401
402/**
403 * struct bfq_io_cq - per (request_queue, io_context) structure.
404 */
405struct bfq_io_cq {
406 /* associated io_cq structure */
407 struct io_cq icq; /* must be the first member */
408 /* array of two process queues, the sync and the async */
409 struct bfq_queue *bfqq[2];
410 /* per (request_queue, blkcg) ioprio */
411 int ioprio;
412#ifdef CONFIG_BFQ_GROUP_IOSCHED
413 uint64_t blkcg_serial_nr; /* the current blkcg serial */
414#endif
415 /*
416 * Snapshot of the has_short_time flag before merging; taken
417 * to remember its value while the queue is merged, so as to
418 * be able to restore it in case of split.
419 */
420 bool saved_has_short_ttime;
421 /*
422 * Same purpose as the previous two fields for the I/O bound
423 * classification of a queue.
424 */
425 bool saved_IO_bound;
426
427 u64 saved_io_start_time;
428 u64 saved_tot_idle_time;
429
430 /*
431 * Same purpose as the previous fields for the value of the
432 * field keeping the queue's belonging to a large burst
433 */
434 bool saved_in_large_burst;
435 /*
436 * True if the queue belonged to a burst list before its merge
437 * with another cooperating queue.
438 */
439 bool was_in_burst_list;
440
441 /*
442 * Save the weight when a merge occurs, to be able
443 * to restore it in case of split. If the weight is not
444 * correctly resumed when the queue is recycled,
445 * then the weight of the recycled queue could differ
446 * from the weight of the original queue.
447 */
448 unsigned int saved_weight;
449
450 /*
451 * Similar to previous fields: save wr information.
452 */
453 unsigned long saved_wr_coeff;
454 unsigned long saved_last_wr_start_finish;
455 unsigned long saved_service_from_wr;
456 unsigned long saved_wr_start_at_switch_to_srt;
457 unsigned int saved_wr_cur_max_time;
458 struct bfq_ttime saved_ttime;
459
460 /* Save also injection state */
461 u64 saved_last_serv_time_ns;
462 unsigned int saved_inject_limit;
463 unsigned long saved_decrease_time_jif;
464
465 /* candidate queue for a stable merge (due to close creation time) */
466 struct bfq_queue *stable_merge_bfqq;
467
468 bool stably_merged; /* non splittable if true */
469};
470
471/**
472 * struct bfq_data - per-device data structure.
473 *
474 * All the fields are protected by @lock.
475 */
476struct bfq_data {
477 /* device request queue */
478 struct request_queue *queue;
479 /* dispatch queue */
480 struct list_head dispatch;
481
482 /* root bfq_group for the device */
483 struct bfq_group *root_group;
484
485 /*
486 * rbtree of weight counters of @bfq_queues, sorted by
487 * weight. Used to keep track of whether all @bfq_queues have
488 * the same weight. The tree contains one counter for each
489 * distinct weight associated to some active and not
490 * weight-raised @bfq_queue (see the comments to the functions
491 * bfq_weights_tree_[add|remove] for further details).
492 */
493 struct rb_root_cached queue_weights_tree;
494
495 /*
496 * Number of groups with at least one descendant process that
497 * has at least one request waiting for completion. Note that
498 * this accounts for also requests already dispatched, but not
499 * yet completed. Therefore this number of groups may differ
500 * (be larger) than the number of active groups, as a group is
501 * considered active only if its corresponding entity has
502 * descendant queues with at least one request queued. This
503 * number is used to decide whether a scenario is symmetric.
504 * For a detailed explanation see comments on the computation
505 * of the variable asymmetric_scenario in the function
506 * bfq_better_to_idle().
507 *
508 * However, it is hard to compute this number exactly, for
509 * groups with multiple descendant processes. Consider a group
510 * that is inactive, i.e., that has no descendant process with
511 * pending I/O inside BFQ queues. Then suppose that
512 * num_groups_with_pending_reqs is still accounting for this
513 * group, because the group has descendant processes with some
514 * I/O request still in flight. num_groups_with_pending_reqs
515 * should be decremented when the in-flight request of the
516 * last descendant process is finally completed (assuming that
517 * nothing else has changed for the group in the meantime, in
518 * terms of composition of the group and active/inactive state of child
519 * groups and processes). To accomplish this, an additional
520 * pending-request counter must be added to entities, and must
521 * be updated correctly. To avoid this additional field and operations,
522 * we resort to the following tradeoff between simplicity and
523 * accuracy: for an inactive group that is still counted in
524 * num_groups_with_pending_reqs, we decrement
525 * num_groups_with_pending_reqs when the first descendant
526 * process of the group remains with no request waiting for
527 * completion.
528 *
529 * Even this simpler decrement strategy requires a little
530 * carefulness: to avoid multiple decrements, we flag a group,
531 * more precisely an entity representing a group, as still
532 * counted in num_groups_with_pending_reqs when it becomes
533 * inactive. Then, when the first descendant queue of the
534 * entity remains with no request waiting for completion,
535 * num_groups_with_pending_reqs is decremented, and this flag
536 * is reset. After this flag is reset for the entity,
537 * num_groups_with_pending_reqs won't be decremented any
538 * longer in case a new descendant queue of the entity remains
539 * with no request waiting for completion.
540 */
541 unsigned int num_groups_with_pending_reqs;
542
543 /*
544 * Per-class (RT, BE, IDLE) number of bfq_queues containing
545 * requests (including the queue in service, even if it is
546 * idling).
547 */
548 unsigned int busy_queues[3];
549 /* number of weight-raised busy @bfq_queues */
550 int wr_busy_queues;
551 /* number of queued requests */
552 int queued;
553 /* number of requests dispatched and waiting for completion */
554 int rq_in_driver;
555
556 /* true if the device is non rotational and performs queueing */
557 bool nonrot_with_queueing;
558
559 /*
560 * Maximum number of requests in driver in the last
561 * @hw_tag_samples completed requests.
562 */
563 int max_rq_in_driver;
564 /* number of samples used to calculate hw_tag */
565 int hw_tag_samples;
566 /* flag set to one if the driver is showing a queueing behavior */
567 int hw_tag;
568
569 /* number of budgets assigned */
570 int budgets_assigned;
571
572 /*
573 * Timer set when idling (waiting) for the next request from
574 * the queue in service.
575 */
576 struct hrtimer idle_slice_timer;
577
578 /* bfq_queue in service */
579 struct bfq_queue *in_service_queue;
580
581 /* on-disk position of the last served request */
582 sector_t last_position;
583
584 /* position of the last served request for the in-service queue */
585 sector_t in_serv_last_pos;
586
587 /* time of last request completion (ns) */
588 u64 last_completion;
589
590 /* bfqq owning the last completed rq */
591 struct bfq_queue *last_completed_rq_bfqq;
592
593 /* last bfqq created, among those in the root group */
594 struct bfq_queue *last_bfqq_created;
595
596 /* time of last transition from empty to non-empty (ns) */
597 u64 last_empty_occupied_ns;
598
599 /*
600 * Flag set to activate the sampling of the total service time
601 * of a just-arrived first I/O request (see
602 * bfq_update_inject_limit()). This will cause the setting of
603 * waited_rq when the request is finally dispatched.
604 */
605 bool wait_dispatch;
606 /*
607 * If set, then bfq_update_inject_limit() is invoked when
608 * waited_rq is eventually completed.
609 */
610 struct request *waited_rq;
611 /*
612 * True if some request has been injected during the last service hole.
613 */
614 bool rqs_injected;
615
616 /* time of first rq dispatch in current observation interval (ns) */
617 u64 first_dispatch;
618 /* time of last rq dispatch in current observation interval (ns) */
619 u64 last_dispatch;
620
621 /* beginning of the last budget */
622 ktime_t last_budget_start;
623 /* beginning of the last idle slice */
624 ktime_t last_idling_start;
625 unsigned long last_idling_start_jiffies;
626
627 /* number of samples in current observation interval */
628 int peak_rate_samples;
629 /* num of samples of seq dispatches in current observation interval */
630 u32 sequential_samples;
631 /* total num of sectors transferred in current observation interval */
632 u64 tot_sectors_dispatched;
633 /* max rq size seen during current observation interval (sectors) */
634 u32 last_rq_max_size;
635 /* time elapsed from first dispatch in current observ. interval (us) */
636 u64 delta_from_first;
637 /*
638 * Current estimate of the device peak rate, measured in
639 * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by
640 * BFQ_RATE_SHIFT is performed to increase precision in
641 * fixed-point calculations.
642 */
643 u32 peak_rate;
644
645 /* maximum budget allotted to a bfq_queue before rescheduling */
646 int bfq_max_budget;
647
648 /* list of all the bfq_queues active on the device */
649 struct list_head active_list;
650 /* list of all the bfq_queues idle on the device */
651 struct list_head idle_list;
652
653 /*
654 * Timeout for async/sync requests; when it fires, requests
655 * are served in fifo order.
656 */
657 u64 bfq_fifo_expire[2];
658 /* weight of backward seeks wrt forward ones */
659 unsigned int bfq_back_penalty;
660 /* maximum allowed backward seek */
661 unsigned int bfq_back_max;
662 /* maximum idling time */
663 u32 bfq_slice_idle;
664
665 /* user-configured max budget value (0 for auto-tuning) */
666 int bfq_user_max_budget;
667 /*
668 * Timeout for bfq_queues to consume their budget; used to
669 * prevent seeky queues from imposing long latencies to
670 * sequential or quasi-sequential ones (this also implies that
671 * seeky queues cannot receive guarantees in the service
672 * domain; after a timeout they are charged for the time they
673 * have been in service, to preserve fairness among them, but
674 * without service-domain guarantees).
675 */
676 unsigned int bfq_timeout;
677
678 /*
679 * Force device idling whenever needed to provide accurate
680 * service guarantees, without caring about throughput
681 * issues. CAVEAT: this may even increase latencies, in case
682 * of useless idling for processes that did stop doing I/O.
683 */
684 bool strict_guarantees;
685
686 /*
687 * Last time at which a queue entered the current burst of
688 * queues being activated shortly after each other; for more
689 * details about this and the following parameters related to
690 * a burst of activations, see the comments on the function
691 * bfq_handle_burst.
692 */
693 unsigned long last_ins_in_burst;
694 /*
695 * Reference time interval used to decide whether a queue has
696 * been activated shortly after @last_ins_in_burst.
697 */
698 unsigned long bfq_burst_interval;
699 /* number of queues in the current burst of queue activations */
700 int burst_size;
701
702 /* common parent entity for the queues in the burst */
703 struct bfq_entity *burst_parent_entity;
704 /* Maximum burst size above which the current queue-activation
705 * burst is deemed as 'large'.
706 */
707 unsigned long bfq_large_burst_thresh;
708 /* true if a large queue-activation burst is in progress */
709 bool large_burst;
710 /*
711 * Head of the burst list (as for the above fields, more
712 * details in the comments on the function bfq_handle_burst).
713 */
714 struct hlist_head burst_list;
715
716 /* if set to true, low-latency heuristics are enabled */
717 bool low_latency;
718 /*
719 * Maximum factor by which the weight of a weight-raised queue
720 * is multiplied.
721 */
722 unsigned int bfq_wr_coeff;
723 /* maximum duration of a weight-raising period (jiffies) */
724 unsigned int bfq_wr_max_time;
725
726 /* Maximum weight-raising duration for soft real-time processes */
727 unsigned int bfq_wr_rt_max_time;
728 /*
729 * Minimum idle period after which weight-raising may be
730 * reactivated for a queue (in jiffies).
731 */
732 unsigned int bfq_wr_min_idle_time;
733 /*
734 * Minimum period between request arrivals after which
735 * weight-raising may be reactivated for an already busy async
736 * queue (in jiffies).
737 */
738 unsigned long bfq_wr_min_inter_arr_async;
739
740 /* Max service-rate for a soft real-time queue, in sectors/sec */
741 unsigned int bfq_wr_max_softrt_rate;
742 /*
743 * Cached value of the product ref_rate*ref_wr_duration, used
744 * for computing the maximum duration of weight raising
745 * automatically.
746 */
747 u64 rate_dur_prod;
748
749 /* fallback dummy bfqq for extreme OOM conditions */
750 struct bfq_queue oom_bfqq;
751
752 spinlock_t lock;
753
754 /*
755 * bic associated with the task issuing current bio for
756 * merging. This and the next field are used as a support to
757 * be able to perform the bic lookup, needed by bio-merge
758 * functions, before the scheduler lock is taken, and thus
759 * avoid taking the request-queue lock while the scheduler
760 * lock is being held.
761 */
762 struct bfq_io_cq *bio_bic;
763 /* bfqq associated with the task issuing current bio for merging */
764 struct bfq_queue *bio_bfqq;
765
766 /*
767 * Depth limits used in bfq_limit_depth (see comments on the
768 * function)
769 */
770 unsigned int word_depths[2][2];
771};
772
773enum bfqq_state_flags {
774 BFQQF_just_created = 0, /* queue just allocated */
775 BFQQF_busy, /* has requests or is in service */
776 BFQQF_wait_request, /* waiting for a request */
777 BFQQF_non_blocking_wait_rq, /*
778 * waiting for a request
779 * without idling the device
780 */
781 BFQQF_fifo_expire, /* FIFO checked in this slice */
782 BFQQF_has_short_ttime, /* queue has a short think time */
783 BFQQF_sync, /* synchronous queue */
784 BFQQF_IO_bound, /*
785 * bfqq has timed-out at least once
786 * having consumed at most 2/10 of
787 * its budget
788 */
789 BFQQF_in_large_burst, /*
790 * bfqq activated in a large burst,
791 * see comments to bfq_handle_burst.
792 */
793 BFQQF_softrt_update, /*
794 * may need softrt-next-start
795 * update
796 */
797 BFQQF_coop, /* bfqq is shared */
798 BFQQF_split_coop, /* shared bfqq will be split */
799};
800
801#define BFQ_BFQQ_FNS(name) \
802void bfq_mark_bfqq_##name(struct bfq_queue *bfqq); \
803void bfq_clear_bfqq_##name(struct bfq_queue *bfqq); \
804int bfq_bfqq_##name(const struct bfq_queue *bfqq);
805
806BFQ_BFQQ_FNS(just_created);
807BFQ_BFQQ_FNS(busy);
808BFQ_BFQQ_FNS(wait_request);
809BFQ_BFQQ_FNS(non_blocking_wait_rq);
810BFQ_BFQQ_FNS(fifo_expire);
811BFQ_BFQQ_FNS(has_short_ttime);
812BFQ_BFQQ_FNS(sync);
813BFQ_BFQQ_FNS(IO_bound);
814BFQ_BFQQ_FNS(in_large_burst);
815BFQ_BFQQ_FNS(coop);
816BFQ_BFQQ_FNS(split_coop);
817BFQ_BFQQ_FNS(softrt_update);
818#undef BFQ_BFQQ_FNS
819
820/* Expiration reasons. */
821enum bfqq_expiration {
822 BFQQE_TOO_IDLE = 0, /*
823 * queue has been idling for
824 * too long
825 */
826 BFQQE_BUDGET_TIMEOUT, /* budget took too long to be used */
827 BFQQE_BUDGET_EXHAUSTED, /* budget consumed */
828 BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */
829 BFQQE_PREEMPTED /* preemption in progress */
830};
831
832struct bfq_stat {
833 struct percpu_counter cpu_cnt;
834 atomic64_t aux_cnt;
835};
836
837struct bfqg_stats {
838 /* basic stats */
839 struct blkg_rwstat bytes;
840 struct blkg_rwstat ios;
841#ifdef CONFIG_BFQ_CGROUP_DEBUG
842 /* number of ios merged */
843 struct blkg_rwstat merged;
844 /* total time spent on device in ns, may not be accurate w/ queueing */
845 struct blkg_rwstat service_time;
846 /* total time spent waiting in scheduler queue in ns */
847 struct blkg_rwstat wait_time;
848 /* number of IOs queued up */
849 struct blkg_rwstat queued;
850 /* total disk time and nr sectors dispatched by this group */
851 struct bfq_stat time;
852 /* sum of number of ios queued across all samples */
853 struct bfq_stat avg_queue_size_sum;
854 /* count of samples taken for average */
855 struct bfq_stat avg_queue_size_samples;
856 /* how many times this group has been removed from service tree */
857 struct bfq_stat dequeue;
858 /* total time spent waiting for it to be assigned a timeslice. */
859 struct bfq_stat group_wait_time;
860 /* time spent idling for this blkcg_gq */
861 struct bfq_stat idle_time;
862 /* total time with empty current active q with other requests queued */
863 struct bfq_stat empty_time;
864 /* fields after this shouldn't be cleared on stat reset */
865 u64 start_group_wait_time;
866 u64 start_idle_time;
867 u64 start_empty_time;
868 uint16_t flags;
869#endif /* CONFIG_BFQ_CGROUP_DEBUG */
870};
871
872#ifdef CONFIG_BFQ_GROUP_IOSCHED
873
874/*
875 * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
876 *
877 * @ps: @blkcg_policy_storage that this structure inherits
878 * @weight: weight of the bfq_group
879 */
880struct bfq_group_data {
881 /* must be the first member */
882 struct blkcg_policy_data pd;
883
884 unsigned int weight;
885};
886
887/**
888 * struct bfq_group - per (device, cgroup) data structure.
889 * @entity: schedulable entity to insert into the parent group sched_data.
890 * @sched_data: own sched_data, to contain child entities (they may be
891 * both bfq_queues and bfq_groups).
892 * @bfqd: the bfq_data for the device this group acts upon.
893 * @async_bfqq: array of async queues for all the tasks belonging to
894 * the group, one queue per ioprio value per ioprio_class,
895 * except for the idle class that has only one queue.
896 * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
897 * @my_entity: pointer to @entity, %NULL for the toplevel group; used
898 * to avoid too many special cases during group creation/
899 * migration.
900 * @stats: stats for this bfqg.
901 * @active_entities: number of active entities belonging to the group;
902 * unused for the root group. Used to know whether there
903 * are groups with more than one active @bfq_entity
904 * (see the comments to the function
905 * bfq_bfqq_may_idle()).
906 * @rq_pos_tree: rbtree sorted by next_request position, used when
907 * determining if two or more queues have interleaving
908 * requests (see bfq_find_close_cooperator()).
909 *
910 * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
911 * there is a set of bfq_groups, each one collecting the lower-level
912 * entities belonging to the group that are acting on the same device.
913 *
914 * Locking works as follows:
915 * o @bfqd is protected by the queue lock, RCU is used to access it
916 * from the readers.
917 * o All the other fields are protected by the @bfqd queue lock.
918 */
919struct bfq_group {
920 /* must be the first member */
921 struct blkg_policy_data pd;
922
923 /* cached path for this blkg (see comments in bfq_bic_update_cgroup) */
924 char blkg_path[128];
925
926 /* reference counter (see comments in bfq_bic_update_cgroup) */
927 int ref;
928
929 struct bfq_entity entity;
930 struct bfq_sched_data sched_data;
931
932 void *bfqd;
933
934 struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
935 struct bfq_queue *async_idle_bfqq;
936
937 struct bfq_entity *my_entity;
938
939 int active_entities;
940
941 struct rb_root rq_pos_tree;
942
943 struct bfqg_stats stats;
944};
945
946#else
947struct bfq_group {
948 struct bfq_entity entity;
949 struct bfq_sched_data sched_data;
950
951 struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
952 struct bfq_queue *async_idle_bfqq;
953
954 struct rb_root rq_pos_tree;
955};
956#endif
957
958struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
959
960/* --------------- main algorithm interface ----------------- */
961
962#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \
963 { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
964
965extern const int bfq_timeout;
966
967struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync);
968void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync);
969struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);
970void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
971void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq,
972 struct rb_root_cached *root);
973void __bfq_weights_tree_remove(struct bfq_data *bfqd,
974 struct bfq_queue *bfqq,
975 struct rb_root_cached *root);
976void bfq_weights_tree_remove(struct bfq_data *bfqd,
977 struct bfq_queue *bfqq);
978void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq,
979 bool compensate, enum bfqq_expiration reason);
980void bfq_put_queue(struct bfq_queue *bfqq);
981void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
982void bfq_release_process_ref(struct bfq_data *bfqd, struct bfq_queue *bfqq);
983void bfq_schedule_dispatch(struct bfq_data *bfqd);
984void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
985
986/* ------------ end of main algorithm interface -------------- */
987
988/* ---------------- cgroups-support interface ---------------- */
989
990void bfqg_stats_update_legacy_io(struct request_queue *q, struct request *rq);
991void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
992 unsigned int op);
993void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op);
994void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op);
995void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
996 u64 io_start_time_ns, unsigned int op);
997void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
998void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
999void bfqg_stats_update_idle_time(struct bfq_group *bfqg);
1000void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg);
1001void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg);
1002void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1003 struct bfq_group *bfqg);
1004
1005void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg);
1006void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio);
1007void bfq_end_wr_async(struct bfq_data *bfqd);
1008struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
1009 struct blkcg *blkcg);
1010struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
1011struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
1012struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node);
1013void bfqg_and_blkg_put(struct bfq_group *bfqg);
1014
1015#ifdef CONFIG_BFQ_GROUP_IOSCHED
1016extern struct cftype bfq_blkcg_legacy_files[];
1017extern struct cftype bfq_blkg_files[];
1018extern struct blkcg_policy blkcg_policy_bfq;
1019#endif
1020
1021/* ------------- end of cgroups-support interface ------------- */
1022
1023/* - interface of the internal hierarchical B-WF2Q+ scheduler - */
1024
1025#ifdef CONFIG_BFQ_GROUP_IOSCHED
1026/* both next loops stop at one of the child entities of the root group */
1027#define for_each_entity(entity) \
1028 for (; entity ; entity = entity->parent)
1029
1030/*
1031 * For each iteration, compute parent in advance, so as to be safe if
1032 * entity is deallocated during the iteration. Such a deallocation may
1033 * happen as a consequence of a bfq_put_queue that frees the bfq_queue
1034 * containing entity.
1035 */
1036#define for_each_entity_safe(entity, parent) \
1037 for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
1038
1039#else /* CONFIG_BFQ_GROUP_IOSCHED */
1040/*
1041 * Next two macros are fake loops when cgroups support is not
1042 * enabled. I fact, in such a case, there is only one level to go up
1043 * (to reach the root group).
1044 */
1045#define for_each_entity(entity) \
1046 for (; entity ; entity = NULL)
1047
1048#define for_each_entity_safe(entity, parent) \
1049 for (parent = NULL; entity ; entity = parent)
1050#endif /* CONFIG_BFQ_GROUP_IOSCHED */
1051
1052struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq);
1053struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
1054unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd);
1055struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);
1056struct bfq_entity *bfq_entity_of(struct rb_node *node);
1057unsigned short bfq_ioprio_to_weight(int ioprio);
1058void bfq_put_idle_entity(struct bfq_service_tree *st,
1059 struct bfq_entity *entity);
1060struct bfq_service_tree *
1061__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
1062 struct bfq_entity *entity,
1063 bool update_class_too);
1064void bfq_bfqq_served(struct bfq_queue *bfqq, int served);
1065void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1066 unsigned long time_ms);
1067bool __bfq_deactivate_entity(struct bfq_entity *entity,
1068 bool ins_into_idle_tree);
1069bool next_queue_may_preempt(struct bfq_data *bfqd);
1070struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd);
1071bool __bfq_bfqd_reset_in_service(struct bfq_data *bfqd);
1072void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1073 bool ins_into_idle_tree, bool expiration);
1074void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
1075void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1076 bool expiration);
1077void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1078 bool expiration);
1079void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq);
1080
1081/* --------------- end of interface of B-WF2Q+ ---------------- */
1082
1083/* Logging facilities. */
1084static inline void bfq_pid_to_str(int pid, char *str, int len)
1085{
1086 if (pid != -1)
1087 snprintf(str, len, "%d", pid);
1088 else
1089 snprintf(str, len, "SHARED-");
1090}
1091
1092#ifdef CONFIG_BFQ_GROUP_IOSCHED
1093struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
1094
1095#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
1096 char pid_str[MAX_PID_STR_LENGTH]; \
1097 if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \
1098 break; \
1099 bfq_pid_to_str((bfqq)->pid, pid_str, MAX_PID_STR_LENGTH); \
1100 blk_add_cgroup_trace_msg((bfqd)->queue, \
1101 bfqg_to_blkg(bfqq_group(bfqq))->blkcg, \
1102 "bfq%s%c " fmt, pid_str, \
1103 bfq_bfqq_sync((bfqq)) ? 'S' : 'A', ##args); \
1104} while (0)
1105
1106#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \
1107 blk_add_cgroup_trace_msg((bfqd)->queue, \
1108 bfqg_to_blkg(bfqg)->blkcg, fmt, ##args); \
1109} while (0)
1110
1111#else /* CONFIG_BFQ_GROUP_IOSCHED */
1112
1113#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
1114 char pid_str[MAX_PID_STR_LENGTH]; \
1115 if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \
1116 break; \
1117 bfq_pid_to_str((bfqq)->pid, pid_str, MAX_PID_STR_LENGTH); \
1118 blk_add_trace_msg((bfqd)->queue, "bfq%s%c " fmt, pid_str, \
1119 bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \
1120 ##args); \
1121} while (0)
1122#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0)
1123
1124#endif /* CONFIG_BFQ_GROUP_IOSCHED */
1125
1126#define bfq_log(bfqd, fmt, args...) \
1127 blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
1128
1129#endif /* _BFQ_H */