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