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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
12#include "blk-cgroup-rwstat.h"
13
14#define BFQ_IOPRIO_CLASSES 3
15#define BFQ_CL_IDLE_TIMEOUT (HZ/5)
16
17#define BFQ_MIN_WEIGHT 1
18#define BFQ_MAX_WEIGHT 1000
19#define BFQ_WEIGHT_CONVERSION_COEFF 10
20
21#define BFQ_DEFAULT_QUEUE_IOPRIO 4
22
23#define BFQ_DEFAULT_GRP_IOPRIO 0
24#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE
25
26#define MAX_BFQQ_NAME_LENGTH 16
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
35/*
36 * Maximum number of actuators supported. This constant is used simply
37 * to define the size of the static array that will contain
38 * per-actuator data. The current value is hopefully a good upper
39 * bound to the possible number of actuators of any actual drive.
40 */
41#define BFQ_MAX_ACTUATORS 8
42
43struct bfq_entity;
44
45/**
46 * struct bfq_service_tree - per ioprio_class service tree.
47 *
48 * Each service tree represents a B-WF2Q+ scheduler on its own. Each
49 * ioprio_class has its own independent scheduler, and so its own
50 * bfq_service_tree. All the fields are protected by the queue lock
51 * of the containing bfqd.
52 */
53struct bfq_service_tree {
54 /* tree for active entities (i.e., those backlogged) */
55 struct rb_root active;
56 /* tree for idle entities (i.e., not backlogged, with V < F_i)*/
57 struct rb_root idle;
58
59 /* idle entity with minimum F_i */
60 struct bfq_entity *first_idle;
61 /* idle entity with maximum F_i */
62 struct bfq_entity *last_idle;
63
64 /* scheduler virtual time */
65 u64 vtime;
66 /* scheduler weight sum; active and idle entities contribute to it */
67 unsigned long wsum;
68};
69
70/**
71 * struct bfq_sched_data - multi-class scheduler.
72 *
73 * bfq_sched_data is the basic scheduler queue. It supports three
74 * ioprio_classes, and can be used either as a toplevel queue or as an
75 * intermediate queue in a hierarchical setup.
76 *
77 * The supported ioprio_classes are the same as in CFQ, in descending
78 * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
79 * Requests from higher priority queues are served before all the
80 * requests from lower priority queues; among requests of the same
81 * queue requests are served according to B-WF2Q+.
82 *
83 * The schedule is implemented by the service trees, plus the field
84 * @next_in_service, which points to the entity on the active trees
85 * that will be served next, if 1) no changes in the schedule occurs
86 * before the current in-service entity is expired, 2) the in-service
87 * queue becomes idle when it expires, and 3) if the entity pointed by
88 * in_service_entity is not a queue, then the in-service child entity
89 * of the entity pointed by in_service_entity becomes idle on
90 * expiration. This peculiar definition allows for the following
91 * optimization, not yet exploited: while a given entity is still in
92 * service, we already know which is the best candidate for next
93 * service among the other active entities in the same parent
94 * entity. We can then quickly compare the timestamps of the
95 * in-service entity with those of such best candidate.
96 *
97 * All fields are protected by the lock of the containing bfqd.
98 */
99struct bfq_sched_data {
100 /* entity in service */
101 struct bfq_entity *in_service_entity;
102 /* head-of-line entity (see comments above) */
103 struct bfq_entity *next_in_service;
104 /* array of service trees, one per ioprio_class */
105 struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
106 /* last time CLASS_IDLE was served */
107 unsigned long bfq_class_idle_last_service;
108
109};
110
111/**
112 * struct bfq_weight_counter - counter of the number of all active queues
113 * with a given weight.
114 */
115struct bfq_weight_counter {
116 unsigned int weight; /* weight of the queues this counter refers to */
117 unsigned int num_active; /* nr of active queues with this weight */
118 /*
119 * Weights tree member (see bfq_data's @queue_weights_tree)
120 */
121 struct rb_node weights_node;
122};
123
124/**
125 * struct bfq_entity - schedulable entity.
126 *
127 * A bfq_entity is used to represent either a bfq_queue (leaf node in the
128 * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each
129 * entity belongs to the sched_data of the parent group in the cgroup
130 * hierarchy. Non-leaf entities have also their own sched_data, stored
131 * in @my_sched_data.
132 *
133 * Each entity stores independently its priority values; this would
134 * allow different weights on different devices, but this
135 * functionality is not exported to userspace by now. Priorities and
136 * weights are updated lazily, first storing the new values into the
137 * new_* fields, then setting the @prio_changed flag. As soon as
138 * there is a transition in the entity state that allows the priority
139 * update to take place the effective and the requested priority
140 * values are synchronized.
141 *
142 * Unless cgroups are used, the weight value is calculated from the
143 * ioprio to export the same interface as CFQ. When dealing with
144 * "well-behaved" queues (i.e., queues that do not spend too much
145 * time to consume their budget and have true sequential behavior, and
146 * when there are no external factors breaking anticipation) the
147 * relative weights at each level of the cgroups hierarchy should be
148 * guaranteed. All the fields are protected by the queue lock of the
149 * containing bfqd.
150 */
151struct bfq_entity {
152 /* service_tree member */
153 struct rb_node rb_node;
154
155 /*
156 * Flag, true if the entity is on a tree (either the active or
157 * the idle one of its service_tree) or is in service.
158 */
159 bool on_st_or_in_serv;
160
161 /* B-WF2Q+ start and finish timestamps [sectors/weight] */
162 u64 start, finish;
163
164 /* tree the entity is enqueued into; %NULL if not on a tree */
165 struct rb_root *tree;
166
167 /*
168 * minimum start time of the (active) subtree rooted at this
169 * entity; used for O(log N) lookups into active trees
170 */
171 u64 min_start;
172
173 /* amount of service received during the last service slot */
174 int service;
175
176 /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
177 int budget;
178
179 /* Number of requests allocated in the subtree of this entity */
180 int allocated;
181
182 /* device weight, if non-zero, it overrides the default weight of
183 * bfq_group_data */
184 int dev_weight;
185 /* weight of the queue */
186 int weight;
187 /* next weight if a change is in progress */
188 int new_weight;
189
190 /* original weight, used to implement weight boosting */
191 int orig_weight;
192
193 /* parent entity, for hierarchical scheduling */
194 struct bfq_entity *parent;
195
196 /*
197 * For non-leaf nodes in the hierarchy, the associated
198 * scheduler queue, %NULL on leaf nodes.
199 */
200 struct bfq_sched_data *my_sched_data;
201 /* the scheduler queue this entity belongs to */
202 struct bfq_sched_data *sched_data;
203
204 /* flag, set to request a weight, ioprio or ioprio_class change */
205 int prio_changed;
206
207#ifdef CONFIG_BFQ_GROUP_IOSCHED
208 /* flag, set if the entity is counted in groups_with_pending_reqs */
209 bool in_groups_with_pending_reqs;
210#endif
211
212 /* last child queue of entity created (for non-leaf entities) */
213 struct bfq_queue *last_bfqq_created;
214};
215
216struct bfq_group;
217
218/**
219 * struct bfq_ttime - per process thinktime stats.
220 */
221struct bfq_ttime {
222 /* completion time of the last request */
223 u64 last_end_request;
224
225 /* total process thinktime */
226 u64 ttime_total;
227 /* number of thinktime samples */
228 unsigned long ttime_samples;
229 /* average process thinktime */
230 u64 ttime_mean;
231};
232
233/**
234 * struct bfq_queue - leaf schedulable entity.
235 *
236 * A bfq_queue is a leaf request queue; it can be associated with an
237 * io_context or more, if it is async or shared between cooperating
238 * processes. Besides, it contains I/O requests for only one actuator
239 * (an io_context is associated with a different bfq_queue for each
240 * actuator it generates I/O for). @cgroup holds a reference to the
241 * cgroup, to be sure that it does not disappear while a bfqq still
242 * references it (mostly to avoid races between request issuing and
243 * task migration followed by cgroup destruction). All the fields are
244 * protected by the queue lock of the containing bfqd.
245 */
246struct bfq_queue {
247 /* reference counter */
248 int ref;
249 /* counter of references from other queues for delayed stable merge */
250 int stable_ref;
251 /* parent bfq_data */
252 struct bfq_data *bfqd;
253
254 /* current ioprio and ioprio class */
255 unsigned short ioprio, ioprio_class;
256 /* next ioprio and ioprio class if a change is in progress */
257 unsigned short new_ioprio, new_ioprio_class;
258
259 /* last total-service-time sample, see bfq_update_inject_limit() */
260 u64 last_serv_time_ns;
261 /* limit for request injection */
262 unsigned int inject_limit;
263 /* last time the inject limit has been decreased, in jiffies */
264 unsigned long decrease_time_jif;
265
266 /*
267 * Shared bfq_queue if queue is cooperating with one or more
268 * other queues.
269 */
270 struct bfq_queue *new_bfqq;
271 /* request-position tree member (see bfq_group's @rq_pos_tree) */
272 struct rb_node pos_node;
273 /* request-position tree root (see bfq_group's @rq_pos_tree) */
274 struct rb_root *pos_root;
275
276 /* sorted list of pending requests */
277 struct rb_root sort_list;
278 /* if fifo isn't expired, next request to serve */
279 struct request *next_rq;
280 /* number of sync and async requests queued */
281 int queued[2];
282 /* number of pending metadata requests */
283 int meta_pending;
284 /* fifo list of requests in sort_list */
285 struct list_head fifo;
286
287 /* entity representing this queue in the scheduler */
288 struct bfq_entity entity;
289
290 /* pointer to the weight counter associated with this entity */
291 struct bfq_weight_counter *weight_counter;
292
293 /* maximum budget allowed from the feedback mechanism */
294 int max_budget;
295 /* budget expiration (in jiffies) */
296 unsigned long budget_timeout;
297
298 /* number of requests on the dispatch list or inside driver */
299 int dispatched;
300
301 /* status flags */
302 unsigned long flags;
303
304 /* node for active/idle bfqq list inside parent bfqd */
305 struct list_head bfqq_list;
306
307 /* associated @bfq_ttime struct */
308 struct bfq_ttime ttime;
309
310 /* when bfqq started to do I/O within the last observation window */
311 u64 io_start_time;
312 /* how long bfqq has remained empty during the last observ. window */
313 u64 tot_idle_time;
314
315 /* bit vector: a 1 for each seeky requests in history */
316 u32 seek_history;
317
318 /* node for the device's burst list */
319 struct hlist_node burst_list_node;
320
321 /* position of the last request enqueued */
322 sector_t last_request_pos;
323
324 /* Number of consecutive pairs of request completion and
325 * arrival, such that the queue becomes idle after the
326 * completion, but the next request arrives within an idle
327 * time slice; used only if the queue's IO_bound flag has been
328 * cleared.
329 */
330 unsigned int requests_within_timer;
331
332 /* pid of the process owning the queue, used for logging purposes */
333 pid_t pid;
334
335 /*
336 * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
337 * if the queue is shared.
338 */
339 struct bfq_io_cq *bic;
340
341 /* current maximum weight-raising time for this queue */
342 unsigned long wr_cur_max_time;
343 /*
344 * Minimum time instant such that, only if a new request is
345 * enqueued after this time instant in an idle @bfq_queue with
346 * no outstanding requests, then the task associated with the
347 * queue it is deemed as soft real-time (see the comments on
348 * the function bfq_bfqq_softrt_next_start())
349 */
350 unsigned long soft_rt_next_start;
351 /*
352 * Start time of the current weight-raising period if
353 * the @bfq-queue is being weight-raised, otherwise
354 * finish time of the last weight-raising period.
355 */
356 unsigned long last_wr_start_finish;
357 /* factor by which the weight of this queue is multiplied */
358 unsigned int wr_coeff;
359 /*
360 * Time of the last transition of the @bfq_queue from idle to
361 * backlogged.
362 */
363 unsigned long last_idle_bklogged;
364 /*
365 * Cumulative service received from the @bfq_queue since the
366 * last transition from idle to backlogged.
367 */
368 unsigned long service_from_backlogged;
369 /*
370 * Cumulative service received from the @bfq_queue since its
371 * last transition to weight-raised state.
372 */
373 unsigned long service_from_wr;
374
375 /*
376 * Value of wr start time when switching to soft rt
377 */
378 unsigned long wr_start_at_switch_to_srt;
379
380 unsigned long split_time; /* time of last split */
381
382 unsigned long first_IO_time; /* time of first I/O for this queue */
383 unsigned long creation_time; /* when this queue is created */
384
385 /*
386 * Pointer to the waker queue for this queue, i.e., to the
387 * queue Q such that this queue happens to get new I/O right
388 * after some I/O request of Q is completed. For details, see
389 * the comments on the choice of the queue for injection in
390 * bfq_select_queue().
391 */
392 struct bfq_queue *waker_bfqq;
393 /* pointer to the curr. tentative waker queue, see bfq_check_waker() */
394 struct bfq_queue *tentative_waker_bfqq;
395 /* number of times the same tentative waker has been detected */
396 unsigned int num_waker_detections;
397 /* time when we started considering this waker */
398 u64 waker_detection_started;
399
400 /* node for woken_list, see below */
401 struct hlist_node woken_list_node;
402 /*
403 * Head of the list of the woken queues for this queue, i.e.,
404 * of the list of the queues for which this queue is a waker
405 * queue. This list is used to reset the waker_bfqq pointer in
406 * the woken queues when this queue exits.
407 */
408 struct hlist_head woken_list;
409
410 /* index of the actuator this queue is associated with */
411 unsigned int actuator_idx;
412};
413
414/**
415* struct bfq_data - bfqq data unique and persistent for associated bfq_io_cq
416*/
417struct bfq_iocq_bfqq_data {
418 /*
419 * Snapshot of the has_short_time flag before merging; taken
420 * to remember its values while the queue is merged, so as to
421 * be able to restore it in case of split.
422 */
423 bool saved_has_short_ttime;
424 /*
425 * Same purpose as the previous two fields for the I/O bound
426 * classification of a queue.
427 */
428 bool saved_IO_bound;
429
430 u64 saved_io_start_time;
431 u64 saved_tot_idle_time;
432
433 /*
434 * Same purpose as the previous fields for the values of the
435 * field keeping the queue's belonging to a large burst
436 */
437 bool saved_in_large_burst;
438 /*
439 * True if the queue belonged to a burst list before its merge
440 * with another cooperating queue.
441 */
442 bool was_in_burst_list;
443
444 /*
445 * Save the weight when a merge occurs, to be able
446 * to restore it in case of split. If the weight is not
447 * correctly resumed when the queue is recycled,
448 * then the weight of the recycled queue could differ
449 * from the weight of the original queue.
450 */
451 unsigned int saved_weight;
452
453 /*
454 * Similar to previous fields: save wr information.
455 */
456 unsigned long saved_wr_coeff;
457 unsigned long saved_last_wr_start_finish;
458 unsigned long saved_service_from_wr;
459 unsigned long saved_wr_start_at_switch_to_srt;
460 unsigned int saved_wr_cur_max_time;
461 struct bfq_ttime saved_ttime;
462
463 /* Save also injection state */
464 u64 saved_last_serv_time_ns;
465 unsigned int saved_inject_limit;
466 unsigned long saved_decrease_time_jif;
467
468 /* candidate queue for a stable merge (due to close creation time) */
469 struct bfq_queue *stable_merge_bfqq;
470
471 bool stably_merged; /* non splittable if true */
472};
473
474/**
475 * struct bfq_io_cq - per (request_queue, io_context) structure.
476 */
477struct bfq_io_cq {
478 /* associated io_cq structure */
479 struct io_cq icq; /* must be the first member */
480 /*
481 * Matrix of associated process queues: first row for async
482 * queues, second row sync queues. Each row contains one
483 * column for each actuator. An I/O request generated by the
484 * process is inserted into the queue pointed by bfqq[i][j] if
485 * the request is to be served by the j-th actuator of the
486 * drive, where i==0 or i==1, depending on whether the request
487 * is async or sync. So there is a distinct queue for each
488 * actuator.
489 */
490 struct bfq_queue *bfqq[2][BFQ_MAX_ACTUATORS];
491 /* per (request_queue, blkcg) ioprio */
492 int ioprio;
493#ifdef CONFIG_BFQ_GROUP_IOSCHED
494 uint64_t blkcg_serial_nr; /* the current blkcg serial */
495#endif
496
497 /*
498 * Persistent data for associated synchronous process queues
499 * (one queue per actuator, see field bfqq above). In
500 * particular, each of these queues may undergo a merge.
501 */
502 struct bfq_iocq_bfqq_data bfqq_data[BFQ_MAX_ACTUATORS];
503
504 unsigned int requests; /* Number of requests this process has in flight */
505};
506
507/**
508 * struct bfq_data - per-device data structure.
509 *
510 * All the fields are protected by @lock.
511 */
512struct bfq_data {
513 /* device request queue */
514 struct request_queue *queue;
515 /* dispatch queue */
516 struct list_head dispatch;
517
518 /* root bfq_group for the device */
519 struct bfq_group *root_group;
520
521 /*
522 * rbtree of weight counters of @bfq_queues, sorted by
523 * weight. Used to keep track of whether all @bfq_queues have
524 * the same weight. The tree contains one counter for each
525 * distinct weight associated to some active and not
526 * weight-raised @bfq_queue (see the comments to the functions
527 * bfq_weights_tree_[add|remove] for further details).
528 */
529 struct rb_root_cached queue_weights_tree;
530
531#ifdef CONFIG_BFQ_GROUP_IOSCHED
532 /*
533 * Number of groups with at least one process that
534 * has at least one request waiting for completion. Note that
535 * this accounts for also requests already dispatched, but not
536 * yet completed. Therefore this number of groups may differ
537 * (be larger) than the number of active groups, as a group is
538 * considered active only if its corresponding entity has
539 * queues with at least one request queued. This
540 * number is used to decide whether a scenario is symmetric.
541 * For a detailed explanation see comments on the computation
542 * of the variable asymmetric_scenario in the function
543 * bfq_better_to_idle().
544 *
545 * However, it is hard to compute this number exactly, for
546 * groups with multiple processes. Consider a group
547 * that is inactive, i.e., that has no process with
548 * pending I/O inside BFQ queues. Then suppose that
549 * num_groups_with_pending_reqs is still accounting for this
550 * group, because the group has processes with some
551 * I/O request still in flight. num_groups_with_pending_reqs
552 * should be decremented when the in-flight request of the
553 * last process is finally completed (assuming that
554 * nothing else has changed for the group in the meantime, in
555 * terms of composition of the group and active/inactive state of child
556 * groups and processes). To accomplish this, an additional
557 * pending-request counter must be added to entities, and must
558 * be updated correctly. To avoid this additional field and operations,
559 * we resort to the following tradeoff between simplicity and
560 * accuracy: for an inactive group that is still counted in
561 * num_groups_with_pending_reqs, we decrement
562 * num_groups_with_pending_reqs when the first
563 * process of the group remains with no request waiting for
564 * completion.
565 *
566 * Even this simpler decrement strategy requires a little
567 * carefulness: to avoid multiple decrements, we flag a group,
568 * more precisely an entity representing a group, as still
569 * counted in num_groups_with_pending_reqs when it becomes
570 * inactive. Then, when the first queue of the
571 * entity remains with no request waiting for completion,
572 * num_groups_with_pending_reqs is decremented, and this flag
573 * is reset. After this flag is reset for the entity,
574 * num_groups_with_pending_reqs won't be decremented any
575 * longer in case a new queue of the entity remains
576 * with no request waiting for completion.
577 */
578 unsigned int num_groups_with_pending_reqs;
579#endif
580
581 /*
582 * Per-class (RT, BE, IDLE) number of bfq_queues containing
583 * requests (including the queue in service, even if it is
584 * idling).
585 */
586 unsigned int busy_queues[3];
587 /* number of weight-raised busy @bfq_queues */
588 int wr_busy_queues;
589 /* number of queued requests */
590 int queued;
591 /* number of requests dispatched and waiting for completion */
592 int tot_rq_in_driver;
593 /*
594 * number of requests dispatched and waiting for completion
595 * for each actuator
596 */
597 int rq_in_driver[BFQ_MAX_ACTUATORS];
598
599 /* true if the device is non rotational and performs queueing */
600 bool nonrot_with_queueing;
601
602 /*
603 * Maximum number of requests in driver in the last
604 * @hw_tag_samples completed requests.
605 */
606 int max_rq_in_driver;
607 /* number of samples used to calculate hw_tag */
608 int hw_tag_samples;
609 /* flag set to one if the driver is showing a queueing behavior */
610 int hw_tag;
611
612 /* number of budgets assigned */
613 int budgets_assigned;
614
615 /*
616 * Timer set when idling (waiting) for the next request from
617 * the queue in service.
618 */
619 struct hrtimer idle_slice_timer;
620
621 /* bfq_queue in service */
622 struct bfq_queue *in_service_queue;
623
624 /* on-disk position of the last served request */
625 sector_t last_position;
626
627 /* position of the last served request for the in-service queue */
628 sector_t in_serv_last_pos;
629
630 /* time of last request completion (ns) */
631 u64 last_completion;
632
633 /* bfqq owning the last completed rq */
634 struct bfq_queue *last_completed_rq_bfqq;
635
636 /* last bfqq created, among those in the root group */
637 struct bfq_queue *last_bfqq_created;
638
639 /* time of last transition from empty to non-empty (ns) */
640 u64 last_empty_occupied_ns;
641
642 /*
643 * Flag set to activate the sampling of the total service time
644 * of a just-arrived first I/O request (see
645 * bfq_update_inject_limit()). This will cause the setting of
646 * waited_rq when the request is finally dispatched.
647 */
648 bool wait_dispatch;
649 /*
650 * If set, then bfq_update_inject_limit() is invoked when
651 * waited_rq is eventually completed.
652 */
653 struct request *waited_rq;
654 /*
655 * True if some request has been injected during the last service hole.
656 */
657 bool rqs_injected;
658
659 /* time of first rq dispatch in current observation interval (ns) */
660 u64 first_dispatch;
661 /* time of last rq dispatch in current observation interval (ns) */
662 u64 last_dispatch;
663
664 /* beginning of the last budget */
665 ktime_t last_budget_start;
666 /* beginning of the last idle slice */
667 ktime_t last_idling_start;
668 unsigned long last_idling_start_jiffies;
669
670 /* number of samples in current observation interval */
671 int peak_rate_samples;
672 /* num of samples of seq dispatches in current observation interval */
673 u32 sequential_samples;
674 /* total num of sectors transferred in current observation interval */
675 u64 tot_sectors_dispatched;
676 /* max rq size seen during current observation interval (sectors) */
677 u32 last_rq_max_size;
678 /* time elapsed from first dispatch in current observ. interval (us) */
679 u64 delta_from_first;
680 /*
681 * Current estimate of the device peak rate, measured in
682 * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by
683 * BFQ_RATE_SHIFT is performed to increase precision in
684 * fixed-point calculations.
685 */
686 u32 peak_rate;
687
688 /* maximum budget allotted to a bfq_queue before rescheduling */
689 int bfq_max_budget;
690
691 /*
692 * List of all the bfq_queues active for a specific actuator
693 * on the device. Keeping active queues separate on a
694 * per-actuator basis helps implementing per-actuator
695 * injection more efficiently.
696 */
697 struct list_head active_list[BFQ_MAX_ACTUATORS];
698 /* list of all the bfq_queues idle on the device */
699 struct list_head idle_list;
700
701 /*
702 * Timeout for async/sync requests; when it fires, requests
703 * are served in fifo order.
704 */
705 u64 bfq_fifo_expire[2];
706 /* weight of backward seeks wrt forward ones */
707 unsigned int bfq_back_penalty;
708 /* maximum allowed backward seek */
709 unsigned int bfq_back_max;
710 /* maximum idling time */
711 u32 bfq_slice_idle;
712
713 /* user-configured max budget value (0 for auto-tuning) */
714 int bfq_user_max_budget;
715 /*
716 * Timeout for bfq_queues to consume their budget; used to
717 * prevent seeky queues from imposing long latencies to
718 * sequential or quasi-sequential ones (this also implies that
719 * seeky queues cannot receive guarantees in the service
720 * domain; after a timeout they are charged for the time they
721 * have been in service, to preserve fairness among them, but
722 * without service-domain guarantees).
723 */
724 unsigned int bfq_timeout;
725
726 /*
727 * Force device idling whenever needed to provide accurate
728 * service guarantees, without caring about throughput
729 * issues. CAVEAT: this may even increase latencies, in case
730 * of useless idling for processes that did stop doing I/O.
731 */
732 bool strict_guarantees;
733
734 /*
735 * Last time at which a queue entered the current burst of
736 * queues being activated shortly after each other; for more
737 * details about this and the following parameters related to
738 * a burst of activations, see the comments on the function
739 * bfq_handle_burst.
740 */
741 unsigned long last_ins_in_burst;
742 /*
743 * Reference time interval used to decide whether a queue has
744 * been activated shortly after @last_ins_in_burst.
745 */
746 unsigned long bfq_burst_interval;
747 /* number of queues in the current burst of queue activations */
748 int burst_size;
749
750 /* common parent entity for the queues in the burst */
751 struct bfq_entity *burst_parent_entity;
752 /* Maximum burst size above which the current queue-activation
753 * burst is deemed as 'large'.
754 */
755 unsigned long bfq_large_burst_thresh;
756 /* true if a large queue-activation burst is in progress */
757 bool large_burst;
758 /*
759 * Head of the burst list (as for the above fields, more
760 * details in the comments on the function bfq_handle_burst).
761 */
762 struct hlist_head burst_list;
763
764 /* if set to true, low-latency heuristics are enabled */
765 bool low_latency;
766 /*
767 * Maximum factor by which the weight of a weight-raised queue
768 * is multiplied.
769 */
770 unsigned int bfq_wr_coeff;
771
772 /* Maximum weight-raising duration for soft real-time processes */
773 unsigned int bfq_wr_rt_max_time;
774 /*
775 * Minimum idle period after which weight-raising may be
776 * reactivated for a queue (in jiffies).
777 */
778 unsigned int bfq_wr_min_idle_time;
779 /*
780 * Minimum period between request arrivals after which
781 * weight-raising may be reactivated for an already busy async
782 * queue (in jiffies).
783 */
784 unsigned long bfq_wr_min_inter_arr_async;
785
786 /* Max service-rate for a soft real-time queue, in sectors/sec */
787 unsigned int bfq_wr_max_softrt_rate;
788 /*
789 * Cached value of the product ref_rate*ref_wr_duration, used
790 * for computing the maximum duration of weight raising
791 * automatically.
792 */
793 u64 rate_dur_prod;
794
795 /* fallback dummy bfqq for extreme OOM conditions */
796 struct bfq_queue oom_bfqq;
797
798 spinlock_t lock;
799
800 /*
801 * bic associated with the task issuing current bio for
802 * merging. This and the next field are used as a support to
803 * be able to perform the bic lookup, needed by bio-merge
804 * functions, before the scheduler lock is taken, and thus
805 * avoid taking the request-queue lock while the scheduler
806 * lock is being held.
807 */
808 struct bfq_io_cq *bio_bic;
809 /* bfqq associated with the task issuing current bio for merging */
810 struct bfq_queue *bio_bfqq;
811
812 /*
813 * Depth limits used in bfq_limit_depth (see comments on the
814 * function)
815 */
816 unsigned int word_depths[2][2];
817 unsigned int full_depth_shift;
818
819 /*
820 * Number of independent actuators. This is equal to 1 in
821 * case of single-actuator drives.
822 */
823 unsigned int num_actuators;
824 /*
825 * Disk independent access ranges for each actuator
826 * in this device.
827 */
828 sector_t sector[BFQ_MAX_ACTUATORS];
829 sector_t nr_sectors[BFQ_MAX_ACTUATORS];
830 struct blk_independent_access_range ia_ranges[BFQ_MAX_ACTUATORS];
831
832 /*
833 * If the number of I/O requests queued in the device for a
834 * given actuator is below next threshold, then the actuator
835 * is deemed as underutilized. If this condition is found to
836 * hold for some actuator upon a dispatch, but (i) the
837 * in-service queue does not contain I/O for that actuator,
838 * while (ii) some other queue does contain I/O for that
839 * actuator, then the head I/O request of the latter queue is
840 * returned (injected), instead of the head request of the
841 * currently in-service queue.
842 *
843 * We set the threshold, empirically, to the minimum possible
844 * value for which an actuator is fully utilized, or close to
845 * be fully utilized. By doing so, injected I/O 'steals' as
846 * few drive-queue slots as possibile to the in-service
847 * queue. This reduces as much as possible the probability
848 * that the service of I/O from the in-service bfq_queue gets
849 * delayed because of slot exhaustion, i.e., because all the
850 * slots of the drive queue are filled with I/O injected from
851 * other queues (NCQ provides for 32 slots).
852 */
853 unsigned int actuator_load_threshold;
854};
855
856enum bfqq_state_flags {
857 BFQQF_just_created = 0, /* queue just allocated */
858 BFQQF_busy, /* has requests or is in service */
859 BFQQF_wait_request, /* waiting for a request */
860 BFQQF_non_blocking_wait_rq, /*
861 * waiting for a request
862 * without idling the device
863 */
864 BFQQF_fifo_expire, /* FIFO checked in this slice */
865 BFQQF_has_short_ttime, /* queue has a short think time */
866 BFQQF_sync, /* synchronous queue */
867 BFQQF_IO_bound, /*
868 * bfqq has timed-out at least once
869 * having consumed at most 2/10 of
870 * its budget
871 */
872 BFQQF_in_large_burst, /*
873 * bfqq activated in a large burst,
874 * see comments to bfq_handle_burst.
875 */
876 BFQQF_softrt_update, /*
877 * may need softrt-next-start
878 * update
879 */
880 BFQQF_coop, /* bfqq is shared */
881 BFQQF_split_coop, /* shared bfqq will be split */
882};
883
884#define BFQ_BFQQ_FNS(name) \
885void bfq_mark_bfqq_##name(struct bfq_queue *bfqq); \
886void bfq_clear_bfqq_##name(struct bfq_queue *bfqq); \
887int bfq_bfqq_##name(const struct bfq_queue *bfqq);
888
889BFQ_BFQQ_FNS(just_created);
890BFQ_BFQQ_FNS(busy);
891BFQ_BFQQ_FNS(wait_request);
892BFQ_BFQQ_FNS(non_blocking_wait_rq);
893BFQ_BFQQ_FNS(fifo_expire);
894BFQ_BFQQ_FNS(has_short_ttime);
895BFQ_BFQQ_FNS(sync);
896BFQ_BFQQ_FNS(IO_bound);
897BFQ_BFQQ_FNS(in_large_burst);
898BFQ_BFQQ_FNS(coop);
899BFQ_BFQQ_FNS(split_coop);
900BFQ_BFQQ_FNS(softrt_update);
901#undef BFQ_BFQQ_FNS
902
903/* Expiration reasons. */
904enum bfqq_expiration {
905 BFQQE_TOO_IDLE = 0, /*
906 * queue has been idling for
907 * too long
908 */
909 BFQQE_BUDGET_TIMEOUT, /* budget took too long to be used */
910 BFQQE_BUDGET_EXHAUSTED, /* budget consumed */
911 BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */
912 BFQQE_PREEMPTED /* preemption in progress */
913};
914
915struct bfq_stat {
916 struct percpu_counter cpu_cnt;
917 atomic64_t aux_cnt;
918};
919
920struct bfqg_stats {
921 /* basic stats */
922 struct blkg_rwstat bytes;
923 struct blkg_rwstat ios;
924#ifdef CONFIG_BFQ_CGROUP_DEBUG
925 /* number of ios merged */
926 struct blkg_rwstat merged;
927 /* total time spent on device in ns, may not be accurate w/ queueing */
928 struct blkg_rwstat service_time;
929 /* total time spent waiting in scheduler queue in ns */
930 struct blkg_rwstat wait_time;
931 /* number of IOs queued up */
932 struct blkg_rwstat queued;
933 /* total disk time and nr sectors dispatched by this group */
934 struct bfq_stat time;
935 /* sum of number of ios queued across all samples */
936 struct bfq_stat avg_queue_size_sum;
937 /* count of samples taken for average */
938 struct bfq_stat avg_queue_size_samples;
939 /* how many times this group has been removed from service tree */
940 struct bfq_stat dequeue;
941 /* total time spent waiting for it to be assigned a timeslice. */
942 struct bfq_stat group_wait_time;
943 /* time spent idling for this blkcg_gq */
944 struct bfq_stat idle_time;
945 /* total time with empty current active q with other requests queued */
946 struct bfq_stat empty_time;
947 /* fields after this shouldn't be cleared on stat reset */
948 u64 start_group_wait_time;
949 u64 start_idle_time;
950 u64 start_empty_time;
951 uint16_t flags;
952#endif /* CONFIG_BFQ_CGROUP_DEBUG */
953};
954
955#ifdef CONFIG_BFQ_GROUP_IOSCHED
956
957/*
958 * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
959 *
960 * @ps: @blkcg_policy_storage that this structure inherits
961 * @weight: weight of the bfq_group
962 */
963struct bfq_group_data {
964 /* must be the first member */
965 struct blkcg_policy_data pd;
966
967 unsigned int weight;
968};
969
970/**
971 * struct bfq_group - per (device, cgroup) data structure.
972 * @entity: schedulable entity to insert into the parent group sched_data.
973 * @sched_data: own sched_data, to contain child entities (they may be
974 * both bfq_queues and bfq_groups).
975 * @bfqd: the bfq_data for the device this group acts upon.
976 * @async_bfqq: array of async queues for all the tasks belonging to
977 * the group, one queue per ioprio value per ioprio_class,
978 * except for the idle class that has only one queue.
979 * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
980 * @my_entity: pointer to @entity, %NULL for the toplevel group; used
981 * to avoid too many special cases during group creation/
982 * migration.
983 * @stats: stats for this bfqg.
984 * @active_entities: number of active entities belonging to the group;
985 * unused for the root group. Used to know whether there
986 * are groups with more than one active @bfq_entity
987 * (see the comments to the function
988 * bfq_bfqq_may_idle()).
989 * @rq_pos_tree: rbtree sorted by next_request position, used when
990 * determining if two or more queues have interleaving
991 * requests (see bfq_find_close_cooperator()).
992 *
993 * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
994 * there is a set of bfq_groups, each one collecting the lower-level
995 * entities belonging to the group that are acting on the same device.
996 *
997 * Locking works as follows:
998 * o @bfqd is protected by the queue lock, RCU is used to access it
999 * from the readers.
1000 * o All the other fields are protected by the @bfqd queue lock.
1001 */
1002struct bfq_group {
1003 /* must be the first member */
1004 struct blkg_policy_data pd;
1005
1006 /* reference counter (see comments in bfq_bic_update_cgroup) */
1007 refcount_t ref;
1008
1009 struct bfq_entity entity;
1010 struct bfq_sched_data sched_data;
1011
1012 struct bfq_data *bfqd;
1013
1014 struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS][BFQ_MAX_ACTUATORS];
1015 struct bfq_queue *async_idle_bfqq[BFQ_MAX_ACTUATORS];
1016
1017 struct bfq_entity *my_entity;
1018
1019 int active_entities;
1020 int num_queues_with_pending_reqs;
1021
1022 struct rb_root rq_pos_tree;
1023
1024 struct bfqg_stats stats;
1025};
1026
1027#else
1028struct bfq_group {
1029 struct bfq_entity entity;
1030 struct bfq_sched_data sched_data;
1031
1032 struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS][BFQ_MAX_ACTUATORS];
1033 struct bfq_queue *async_idle_bfqq[BFQ_MAX_ACTUATORS];
1034
1035 struct rb_root rq_pos_tree;
1036};
1037#endif
1038
1039/* --------------- main algorithm interface ----------------- */
1040
1041#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \
1042 { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
1043
1044extern const int bfq_timeout;
1045
1046struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync,
1047 unsigned int actuator_idx);
1048void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync,
1049 unsigned int actuator_idx);
1050struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);
1051void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
1052void bfq_weights_tree_add(struct bfq_queue *bfqq);
1053void bfq_weights_tree_remove(struct bfq_queue *bfqq);
1054void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1055 bool compensate, enum bfqq_expiration reason);
1056void bfq_put_queue(struct bfq_queue *bfqq);
1057void bfq_put_cooperator(struct bfq_queue *bfqq);
1058void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
1059void bfq_release_process_ref(struct bfq_data *bfqd, struct bfq_queue *bfqq);
1060void bfq_schedule_dispatch(struct bfq_data *bfqd);
1061void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
1062
1063/* ------------ end of main algorithm interface -------------- */
1064
1065/* ---------------- cgroups-support interface ---------------- */
1066
1067void bfqg_stats_update_legacy_io(struct request_queue *q, struct request *rq);
1068void bfqg_stats_update_io_remove(struct bfq_group *bfqg, blk_opf_t opf);
1069void bfqg_stats_update_io_merged(struct bfq_group *bfqg, blk_opf_t opf);
1070void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
1071 u64 io_start_time_ns, blk_opf_t opf);
1072void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
1073void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg);
1074void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1075 struct bfq_group *bfqg);
1076
1077#ifdef CONFIG_BFQ_CGROUP_DEBUG
1078void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
1079 blk_opf_t opf);
1080void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
1081void bfqg_stats_update_idle_time(struct bfq_group *bfqg);
1082void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg);
1083#endif
1084
1085void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg);
1086void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio);
1087void bfq_end_wr_async(struct bfq_data *bfqd);
1088struct bfq_group *bfq_bio_bfqg(struct bfq_data *bfqd, struct bio *bio);
1089struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
1090struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
1091struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node);
1092void bfqg_and_blkg_put(struct bfq_group *bfqg);
1093
1094#ifdef CONFIG_BFQ_GROUP_IOSCHED
1095extern struct cftype bfq_blkcg_legacy_files[];
1096extern struct cftype bfq_blkg_files[];
1097extern struct blkcg_policy blkcg_policy_bfq;
1098#endif
1099
1100/* ------------- end of cgroups-support interface ------------- */
1101
1102/* - interface of the internal hierarchical B-WF2Q+ scheduler - */
1103
1104#ifdef CONFIG_BFQ_GROUP_IOSCHED
1105/* both next loops stop at one of the child entities of the root group */
1106#define for_each_entity(entity) \
1107 for (; entity ; entity = entity->parent)
1108
1109/*
1110 * For each iteration, compute parent in advance, so as to be safe if
1111 * entity is deallocated during the iteration. Such a deallocation may
1112 * happen as a consequence of a bfq_put_queue that frees the bfq_queue
1113 * containing entity.
1114 */
1115#define for_each_entity_safe(entity, parent) \
1116 for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
1117
1118#else /* CONFIG_BFQ_GROUP_IOSCHED */
1119/*
1120 * Next two macros are fake loops when cgroups support is not
1121 * enabled. I fact, in such a case, there is only one level to go up
1122 * (to reach the root group).
1123 */
1124#define for_each_entity(entity) \
1125 for (; entity ; entity = NULL)
1126
1127#define for_each_entity_safe(entity, parent) \
1128 for (parent = NULL; entity ; entity = parent)
1129#endif /* CONFIG_BFQ_GROUP_IOSCHED */
1130
1131struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
1132unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd);
1133struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);
1134struct bfq_entity *bfq_entity_of(struct rb_node *node);
1135unsigned short bfq_ioprio_to_weight(int ioprio);
1136void bfq_put_idle_entity(struct bfq_service_tree *st,
1137 struct bfq_entity *entity);
1138struct bfq_service_tree *
1139__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
1140 struct bfq_entity *entity,
1141 bool update_class_too);
1142void bfq_bfqq_served(struct bfq_queue *bfqq, int served);
1143void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1144 unsigned long time_ms);
1145bool __bfq_deactivate_entity(struct bfq_entity *entity,
1146 bool ins_into_idle_tree);
1147bool next_queue_may_preempt(struct bfq_data *bfqd);
1148struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd);
1149bool __bfq_bfqd_reset_in_service(struct bfq_data *bfqd);
1150void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1151 bool ins_into_idle_tree, bool expiration);
1152void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
1153void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1154 bool expiration);
1155void bfq_del_bfqq_busy(struct bfq_queue *bfqq, bool expiration);
1156void bfq_add_bfqq_busy(struct bfq_queue *bfqq);
1157void bfq_add_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq);
1158void bfq_del_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq);
1159void bfq_reassign_last_bfqq(struct bfq_queue *cur_bfqq,
1160 struct bfq_queue *new_bfqq);
1161
1162/* --------------- end of interface of B-WF2Q+ ---------------- */
1163
1164/* Logging facilities. */
1165static inline void bfq_bfqq_name(struct bfq_queue *bfqq, char *str, int len)
1166{
1167 char type = bfq_bfqq_sync(bfqq) ? 'S' : 'A';
1168
1169 if (bfqq->pid != -1)
1170 snprintf(str, len, "bfq%d%c", bfqq->pid, type);
1171 else
1172 snprintf(str, len, "bfqSHARED-%c", type);
1173}
1174
1175#ifdef CONFIG_BFQ_GROUP_IOSCHED
1176struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
1177
1178#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
1179 char pid_str[MAX_BFQQ_NAME_LENGTH]; \
1180 if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \
1181 break; \
1182 bfq_bfqq_name((bfqq), pid_str, MAX_BFQQ_NAME_LENGTH); \
1183 blk_add_cgroup_trace_msg((bfqd)->queue, \
1184 &bfqg_to_blkg(bfqq_group(bfqq))->blkcg->css, \
1185 "%s " fmt, pid_str, ##args); \
1186} while (0)
1187
1188#else /* CONFIG_BFQ_GROUP_IOSCHED */
1189
1190#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
1191 char pid_str[MAX_BFQQ_NAME_LENGTH]; \
1192 if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \
1193 break; \
1194 bfq_bfqq_name((bfqq), pid_str, MAX_BFQQ_NAME_LENGTH); \
1195 blk_add_trace_msg((bfqd)->queue, "%s " fmt, pid_str, ##args); \
1196} while (0)
1197
1198#endif /* CONFIG_BFQ_GROUP_IOSCHED */
1199
1200#define bfq_log(bfqd, fmt, args...) \
1201 blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
1202
1203#endif /* _BFQ_H */