blob: 78b2e0db4fb2c0adba7f0b7ec089cf61f0f311c8 [file] [log] [blame]
Paolo Valenteea25da42017-04-19 08:48:24 -06001/*
2 * cgroups support for the BFQ I/O scheduler.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 */
14#include <linux/module.h>
15#include <linux/slab.h>
16#include <linux/blkdev.h>
17#include <linux/cgroup.h>
18#include <linux/elevator.h>
19#include <linux/ktime.h>
20#include <linux/rbtree.h>
21#include <linux/ioprio.h>
22#include <linux/sbitmap.h>
23#include <linux/delay.h>
24
25#include "bfq-iosched.h"
26
27#ifdef CONFIG_BFQ_GROUP_IOSCHED
28
29/* bfqg stats flags */
30enum bfqg_stats_flags {
31 BFQG_stats_waiting = 0,
32 BFQG_stats_idling,
33 BFQG_stats_empty,
34};
35
36#define BFQG_FLAG_FNS(name) \
37static void bfqg_stats_mark_##name(struct bfqg_stats *stats) \
38{ \
39 stats->flags |= (1 << BFQG_stats_##name); \
40} \
41static void bfqg_stats_clear_##name(struct bfqg_stats *stats) \
42{ \
43 stats->flags &= ~(1 << BFQG_stats_##name); \
44} \
45static int bfqg_stats_##name(struct bfqg_stats *stats) \
46{ \
47 return (stats->flags & (1 << BFQG_stats_##name)) != 0; \
48} \
49
50BFQG_FLAG_FNS(waiting)
51BFQG_FLAG_FNS(idling)
52BFQG_FLAG_FNS(empty)
53#undef BFQG_FLAG_FNS
54
Paolo Valente8f9bebc2017-06-05 10:11:15 +020055/* This should be called with the scheduler lock held. */
Paolo Valenteea25da42017-04-19 08:48:24 -060056static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
57{
58 unsigned long long now;
59
60 if (!bfqg_stats_waiting(stats))
61 return;
62
63 now = sched_clock();
64 if (time_after64(now, stats->start_group_wait_time))
65 blkg_stat_add(&stats->group_wait_time,
66 now - stats->start_group_wait_time);
67 bfqg_stats_clear_waiting(stats);
68}
69
Paolo Valente8f9bebc2017-06-05 10:11:15 +020070/* This should be called with the scheduler lock held. */
Paolo Valenteea25da42017-04-19 08:48:24 -060071static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
72 struct bfq_group *curr_bfqg)
73{
74 struct bfqg_stats *stats = &bfqg->stats;
75
76 if (bfqg_stats_waiting(stats))
77 return;
78 if (bfqg == curr_bfqg)
79 return;
80 stats->start_group_wait_time = sched_clock();
81 bfqg_stats_mark_waiting(stats);
82}
83
Paolo Valente8f9bebc2017-06-05 10:11:15 +020084/* This should be called with the scheduler lock held. */
Paolo Valenteea25da42017-04-19 08:48:24 -060085static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
86{
87 unsigned long long now;
88
89 if (!bfqg_stats_empty(stats))
90 return;
91
92 now = sched_clock();
93 if (time_after64(now, stats->start_empty_time))
94 blkg_stat_add(&stats->empty_time,
95 now - stats->start_empty_time);
96 bfqg_stats_clear_empty(stats);
97}
98
99void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
100{
101 blkg_stat_add(&bfqg->stats.dequeue, 1);
102}
103
104void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
105{
106 struct bfqg_stats *stats = &bfqg->stats;
107
108 if (blkg_rwstat_total(&stats->queued))
109 return;
110
111 /*
112 * group is already marked empty. This can happen if bfqq got new
113 * request in parent group and moved to this group while being added
114 * to service tree. Just ignore the event and move on.
115 */
116 if (bfqg_stats_empty(stats))
117 return;
118
119 stats->start_empty_time = sched_clock();
120 bfqg_stats_mark_empty(stats);
121}
122
123void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
124{
125 struct bfqg_stats *stats = &bfqg->stats;
126
127 if (bfqg_stats_idling(stats)) {
128 unsigned long long now = sched_clock();
129
130 if (time_after64(now, stats->start_idle_time))
131 blkg_stat_add(&stats->idle_time,
132 now - stats->start_idle_time);
133 bfqg_stats_clear_idling(stats);
134 }
135}
136
137void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg)
138{
139 struct bfqg_stats *stats = &bfqg->stats;
140
141 stats->start_idle_time = sched_clock();
142 bfqg_stats_mark_idling(stats);
143}
144
145void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
146{
147 struct bfqg_stats *stats = &bfqg->stats;
148
149 blkg_stat_add(&stats->avg_queue_size_sum,
150 blkg_rwstat_total(&stats->queued));
151 blkg_stat_add(&stats->avg_queue_size_samples, 1);
152 bfqg_stats_update_group_wait_time(stats);
153}
154
155/*
156 * blk-cgroup policy-related handlers
157 * The following functions help in converting between blk-cgroup
158 * internal structures and BFQ-specific structures.
159 */
160
161static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd)
162{
163 return pd ? container_of(pd, struct bfq_group, pd) : NULL;
164}
165
166struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg)
167{
168 return pd_to_blkg(&bfqg->pd);
169}
170
171static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg)
172{
173 return pd_to_bfqg(blkg_to_pd(blkg, &blkcg_policy_bfq));
174}
175
176/*
177 * bfq_group handlers
178 * The following functions help in navigating the bfq_group hierarchy
179 * by allowing to find the parent of a bfq_group or the bfq_group
180 * associated to a bfq_queue.
181 */
182
183static struct bfq_group *bfqg_parent(struct bfq_group *bfqg)
184{
185 struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent;
186
187 return pblkg ? blkg_to_bfqg(pblkg) : NULL;
188}
189
190struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
191{
192 struct bfq_entity *group_entity = bfqq->entity.parent;
193
194 return group_entity ? container_of(group_entity, struct bfq_group,
195 entity) :
196 bfqq->bfqd->root_group;
197}
198
199/*
200 * The following two functions handle get and put of a bfq_group by
201 * wrapping the related blk-cgroup hooks.
202 */
203
204static void bfqg_get(struct bfq_group *bfqg)
205{
Paolo Valente8f9bebc2017-06-05 10:11:15 +0200206 bfqg->ref++;
Paolo Valenteea25da42017-04-19 08:48:24 -0600207}
208
209void bfqg_put(struct bfq_group *bfqg)
210{
Paolo Valente8f9bebc2017-06-05 10:11:15 +0200211 bfqg->ref--;
212
213 if (bfqg->ref == 0)
214 kfree(bfqg);
215}
216
217static void bfqg_and_blkg_get(struct bfq_group *bfqg)
218{
219 /* see comments in bfq_bic_update_cgroup for why refcounting bfqg */
220 bfqg_get(bfqg);
221
222 blkg_get(bfqg_to_blkg(bfqg));
223}
224
225void bfqg_and_blkg_put(struct bfq_group *bfqg)
226{
227 bfqg_put(bfqg);
228
229 blkg_put(bfqg_to_blkg(bfqg));
Paolo Valenteea25da42017-04-19 08:48:24 -0600230}
231
232void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
233 unsigned int op)
234{
235 blkg_rwstat_add(&bfqg->stats.queued, op, 1);
236 bfqg_stats_end_empty_time(&bfqg->stats);
237 if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
238 bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
239}
240
241void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op)
242{
243 blkg_rwstat_add(&bfqg->stats.queued, op, -1);
244}
245
246void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op)
247{
248 blkg_rwstat_add(&bfqg->stats.merged, op, 1);
249}
250
251void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time,
252 uint64_t io_start_time, unsigned int op)
253{
254 struct bfqg_stats *stats = &bfqg->stats;
255 unsigned long long now = sched_clock();
256
257 if (time_after64(now, io_start_time))
258 blkg_rwstat_add(&stats->service_time, op,
259 now - io_start_time);
260 if (time_after64(io_start_time, start_time))
261 blkg_rwstat_add(&stats->wait_time, op,
262 io_start_time - start_time);
263}
264
265/* @stats = 0 */
266static void bfqg_stats_reset(struct bfqg_stats *stats)
267{
268 /* queued stats shouldn't be cleared */
269 blkg_rwstat_reset(&stats->merged);
270 blkg_rwstat_reset(&stats->service_time);
271 blkg_rwstat_reset(&stats->wait_time);
272 blkg_stat_reset(&stats->time);
273 blkg_stat_reset(&stats->avg_queue_size_sum);
274 blkg_stat_reset(&stats->avg_queue_size_samples);
275 blkg_stat_reset(&stats->dequeue);
276 blkg_stat_reset(&stats->group_wait_time);
277 blkg_stat_reset(&stats->idle_time);
278 blkg_stat_reset(&stats->empty_time);
279}
280
281/* @to += @from */
282static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
283{
284 if (!to || !from)
285 return;
286
287 /* queued stats shouldn't be cleared */
288 blkg_rwstat_add_aux(&to->merged, &from->merged);
289 blkg_rwstat_add_aux(&to->service_time, &from->service_time);
290 blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
291 blkg_stat_add_aux(&from->time, &from->time);
292 blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
293 blkg_stat_add_aux(&to->avg_queue_size_samples,
294 &from->avg_queue_size_samples);
295 blkg_stat_add_aux(&to->dequeue, &from->dequeue);
296 blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
297 blkg_stat_add_aux(&to->idle_time, &from->idle_time);
298 blkg_stat_add_aux(&to->empty_time, &from->empty_time);
299}
300
301/*
302 * Transfer @bfqg's stats to its parent's aux counts so that the ancestors'
303 * recursive stats can still account for the amount used by this bfqg after
304 * it's gone.
305 */
306static void bfqg_stats_xfer_dead(struct bfq_group *bfqg)
307{
308 struct bfq_group *parent;
309
310 if (!bfqg) /* root_group */
311 return;
312
313 parent = bfqg_parent(bfqg);
314
315 lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock);
316
317 if (unlikely(!parent))
318 return;
319
320 bfqg_stats_add_aux(&parent->stats, &bfqg->stats);
321 bfqg_stats_reset(&bfqg->stats);
322}
323
324void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg)
325{
326 struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
327
328 entity->weight = entity->new_weight;
329 entity->orig_weight = entity->new_weight;
330 if (bfqq) {
331 bfqq->ioprio = bfqq->new_ioprio;
332 bfqq->ioprio_class = bfqq->new_ioprio_class;
Paolo Valente8f9bebc2017-06-05 10:11:15 +0200333 /*
334 * Make sure that bfqg and its associated blkg do not
335 * disappear before entity.
336 */
337 bfqg_and_blkg_get(bfqg);
Paolo Valenteea25da42017-04-19 08:48:24 -0600338 }
339 entity->parent = bfqg->my_entity; /* NULL for root group */
340 entity->sched_data = &bfqg->sched_data;
341}
342
343static void bfqg_stats_exit(struct bfqg_stats *stats)
344{
345 blkg_rwstat_exit(&stats->merged);
346 blkg_rwstat_exit(&stats->service_time);
347 blkg_rwstat_exit(&stats->wait_time);
348 blkg_rwstat_exit(&stats->queued);
349 blkg_stat_exit(&stats->time);
350 blkg_stat_exit(&stats->avg_queue_size_sum);
351 blkg_stat_exit(&stats->avg_queue_size_samples);
352 blkg_stat_exit(&stats->dequeue);
353 blkg_stat_exit(&stats->group_wait_time);
354 blkg_stat_exit(&stats->idle_time);
355 blkg_stat_exit(&stats->empty_time);
356}
357
358static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
359{
360 if (blkg_rwstat_init(&stats->merged, gfp) ||
361 blkg_rwstat_init(&stats->service_time, gfp) ||
362 blkg_rwstat_init(&stats->wait_time, gfp) ||
363 blkg_rwstat_init(&stats->queued, gfp) ||
364 blkg_stat_init(&stats->time, gfp) ||
365 blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
366 blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
367 blkg_stat_init(&stats->dequeue, gfp) ||
368 blkg_stat_init(&stats->group_wait_time, gfp) ||
369 blkg_stat_init(&stats->idle_time, gfp) ||
370 blkg_stat_init(&stats->empty_time, gfp)) {
371 bfqg_stats_exit(stats);
372 return -ENOMEM;
373 }
374
375 return 0;
376}
377
378static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)
379{
380 return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL;
381}
382
383static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg)
384{
385 return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq));
386}
387
388struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
389{
390 struct bfq_group_data *bgd;
391
392 bgd = kzalloc(sizeof(*bgd), gfp);
393 if (!bgd)
394 return NULL;
395 return &bgd->pd;
396}
397
398void bfq_cpd_init(struct blkcg_policy_data *cpd)
399{
400 struct bfq_group_data *d = cpd_to_bfqgd(cpd);
401
402 d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
403 CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL;
404}
405
406void bfq_cpd_free(struct blkcg_policy_data *cpd)
407{
408 kfree(cpd_to_bfqgd(cpd));
409}
410
411struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
412{
413 struct bfq_group *bfqg;
414
415 bfqg = kzalloc_node(sizeof(*bfqg), gfp, node);
416 if (!bfqg)
417 return NULL;
418
419 if (bfqg_stats_init(&bfqg->stats, gfp)) {
420 kfree(bfqg);
421 return NULL;
422 }
423
Paolo Valente8f9bebc2017-06-05 10:11:15 +0200424 /* see comments in bfq_bic_update_cgroup for why refcounting */
425 bfqg_get(bfqg);
Paolo Valenteea25da42017-04-19 08:48:24 -0600426 return &bfqg->pd;
427}
428
429void bfq_pd_init(struct blkg_policy_data *pd)
430{
431 struct blkcg_gq *blkg = pd_to_blkg(pd);
432 struct bfq_group *bfqg = blkg_to_bfqg(blkg);
433 struct bfq_data *bfqd = blkg->q->elevator->elevator_data;
434 struct bfq_entity *entity = &bfqg->entity;
435 struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg);
436
437 entity->orig_weight = entity->weight = entity->new_weight = d->weight;
438 entity->my_sched_data = &bfqg->sched_data;
439 bfqg->my_entity = entity; /*
440 * the root_group's will be set to NULL
441 * in bfq_init_queue()
442 */
443 bfqg->bfqd = bfqd;
444 bfqg->active_entities = 0;
445 bfqg->rq_pos_tree = RB_ROOT;
446}
447
448void bfq_pd_free(struct blkg_policy_data *pd)
449{
450 struct bfq_group *bfqg = pd_to_bfqg(pd);
451
452 bfqg_stats_exit(&bfqg->stats);
Paolo Valente8f9bebc2017-06-05 10:11:15 +0200453 bfqg_put(bfqg);
Paolo Valenteea25da42017-04-19 08:48:24 -0600454}
455
456void bfq_pd_reset_stats(struct blkg_policy_data *pd)
457{
458 struct bfq_group *bfqg = pd_to_bfqg(pd);
459
460 bfqg_stats_reset(&bfqg->stats);
461}
462
463static void bfq_group_set_parent(struct bfq_group *bfqg,
464 struct bfq_group *parent)
465{
466 struct bfq_entity *entity;
467
468 entity = &bfqg->entity;
469 entity->parent = parent->my_entity;
470 entity->sched_data = &parent->sched_data;
471}
472
473static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd,
474 struct blkcg *blkcg)
475{
476 struct blkcg_gq *blkg;
477
478 blkg = blkg_lookup(blkcg, bfqd->queue);
479 if (likely(blkg))
480 return blkg_to_bfqg(blkg);
481 return NULL;
482}
483
484struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
485 struct blkcg *blkcg)
486{
487 struct bfq_group *bfqg, *parent;
488 struct bfq_entity *entity;
489
490 bfqg = bfq_lookup_bfqg(bfqd, blkcg);
491
492 if (unlikely(!bfqg))
493 return NULL;
494
495 /*
496 * Update chain of bfq_groups as we might be handling a leaf group
497 * which, along with some of its relatives, has not been hooked yet
498 * to the private hierarchy of BFQ.
499 */
500 entity = &bfqg->entity;
501 for_each_entity(entity) {
502 bfqg = container_of(entity, struct bfq_group, entity);
503 if (bfqg != bfqd->root_group) {
504 parent = bfqg_parent(bfqg);
505 if (!parent)
506 parent = bfqd->root_group;
507 bfq_group_set_parent(bfqg, parent);
508 }
509 }
510
511 return bfqg;
512}
513
514/**
515 * bfq_bfqq_move - migrate @bfqq to @bfqg.
516 * @bfqd: queue descriptor.
517 * @bfqq: the queue to move.
518 * @bfqg: the group to move to.
519 *
520 * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
521 * it on the new one. Avoid putting the entity on the old group idle tree.
522 *
Paolo Valente8f9bebc2017-06-05 10:11:15 +0200523 * Must be called under the scheduler lock, to make sure that the blkg
524 * owning @bfqg does not disappear (see comments in
525 * bfq_bic_update_cgroup on guaranteeing the consistency of blkg
526 * objects).
Paolo Valenteea25da42017-04-19 08:48:24 -0600527 */
528void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
529 struct bfq_group *bfqg)
530{
531 struct bfq_entity *entity = &bfqq->entity;
532
533 /* If bfqq is empty, then bfq_bfqq_expire also invokes
534 * bfq_del_bfqq_busy, thereby removing bfqq and its entity
535 * from data structures related to current group. Otherwise we
536 * need to remove bfqq explicitly with bfq_deactivate_bfqq, as
537 * we do below.
538 */
539 if (bfqq == bfqd->in_service_queue)
540 bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
541 false, BFQQE_PREEMPTED);
542
543 if (bfq_bfqq_busy(bfqq))
544 bfq_deactivate_bfqq(bfqd, bfqq, false, false);
545 else if (entity->on_st)
546 bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
Paolo Valente8f9bebc2017-06-05 10:11:15 +0200547 bfqg_and_blkg_put(bfqq_group(bfqq));
Paolo Valenteea25da42017-04-19 08:48:24 -0600548
Paolo Valenteea25da42017-04-19 08:48:24 -0600549 entity->parent = bfqg->my_entity;
550 entity->sched_data = &bfqg->sched_data;
Paolo Valente8f9bebc2017-06-05 10:11:15 +0200551 /* pin down bfqg and its associated blkg */
552 bfqg_and_blkg_get(bfqg);
Paolo Valenteea25da42017-04-19 08:48:24 -0600553
554 if (bfq_bfqq_busy(bfqq)) {
555 bfq_pos_tree_add_move(bfqd, bfqq);
556 bfq_activate_bfqq(bfqd, bfqq);
557 }
558
559 if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
560 bfq_schedule_dispatch(bfqd);
561}
562
563/**
564 * __bfq_bic_change_cgroup - move @bic to @cgroup.
565 * @bfqd: the queue descriptor.
566 * @bic: the bic to move.
567 * @blkcg: the blk-cgroup to move to.
568 *
Paolo Valente8f9bebc2017-06-05 10:11:15 +0200569 * Move bic to blkcg, assuming that bfqd->lock is held; which makes
570 * sure that the reference to cgroup is valid across the call (see
571 * comments in bfq_bic_update_cgroup on this issue)
Paolo Valenteea25da42017-04-19 08:48:24 -0600572 *
573 * NOTE: an alternative approach might have been to store the current
574 * cgroup in bfqq and getting a reference to it, reducing the lookup
575 * time here, at the price of slightly more complex code.
576 */
577static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
578 struct bfq_io_cq *bic,
579 struct blkcg *blkcg)
580{
581 struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0);
582 struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1);
583 struct bfq_group *bfqg;
584 struct bfq_entity *entity;
585
586 bfqg = bfq_find_set_group(bfqd, blkcg);
587
588 if (unlikely(!bfqg))
589 bfqg = bfqd->root_group;
590
591 if (async_bfqq) {
592 entity = &async_bfqq->entity;
593
594 if (entity->sched_data != &bfqg->sched_data) {
595 bic_set_bfqq(bic, NULL, 0);
596 bfq_log_bfqq(bfqd, async_bfqq,
597 "bic_change_group: %p %d",
598 async_bfqq, async_bfqq->ref);
599 bfq_put_queue(async_bfqq);
600 }
601 }
602
603 if (sync_bfqq) {
604 entity = &sync_bfqq->entity;
605 if (entity->sched_data != &bfqg->sched_data)
606 bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
607 }
608
609 return bfqg;
610}
611
612void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
613{
614 struct bfq_data *bfqd = bic_to_bfqd(bic);
615 struct bfq_group *bfqg = NULL;
616 uint64_t serial_nr;
617
618 rcu_read_lock();
619 serial_nr = bio_blkcg(bio)->css.serial_nr;
620
621 /*
622 * Check whether blkcg has changed. The condition may trigger
623 * spuriously on a newly created cic but there's no harm.
624 */
625 if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr))
626 goto out;
627
628 bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio));
Paolo Valente8f9bebc2017-06-05 10:11:15 +0200629 /*
630 * Update blkg_path for bfq_log_* functions. We cache this
631 * path, and update it here, for the following
632 * reasons. Operations on blkg objects in blk-cgroup are
633 * protected with the request_queue lock, and not with the
634 * lock that protects the instances of this scheduler
635 * (bfqd->lock). This exposes BFQ to the following sort of
636 * race.
637 *
638 * The blkg_lookup performed in bfq_get_queue, protected
639 * through rcu, may happen to return the address of a copy of
640 * the original blkg. If this is the case, then the
641 * bfqg_and_blkg_get performed in bfq_get_queue, to pin down
642 * the blkg, is useless: it does not prevent blk-cgroup code
643 * from destroying both the original blkg and all objects
644 * directly or indirectly referred by the copy of the
645 * blkg.
646 *
647 * On the bright side, destroy operations on a blkg invoke, as
648 * a first step, hooks of the scheduler associated with the
649 * blkg. And these hooks are executed with bfqd->lock held for
650 * BFQ. As a consequence, for any blkg associated with the
651 * request queue this instance of the scheduler is attached
652 * to, we are guaranteed that such a blkg is not destroyed, and
653 * that all the pointers it contains are consistent, while we
654 * are holding bfqd->lock. A blkg_lookup performed with
655 * bfqd->lock held then returns a fully consistent blkg, which
656 * remains consistent until this lock is held.
657 *
658 * Thanks to the last fact, and to the fact that: (1) bfqg has
659 * been obtained through a blkg_lookup in the above
660 * assignment, and (2) bfqd->lock is being held, here we can
661 * safely use the policy data for the involved blkg (i.e., the
662 * field bfqg->pd) to get to the blkg associated with bfqg,
663 * and then we can safely use any field of blkg. After we
664 * release bfqd->lock, even just getting blkg through this
665 * bfqg may cause dangling references to be traversed, as
666 * bfqg->pd may not exist any more.
667 *
668 * In view of the above facts, here we cache, in the bfqg, any
669 * blkg data we may need for this bic, and for its associated
670 * bfq_queue. As of now, we need to cache only the path of the
671 * blkg, which is used in the bfq_log_* functions.
672 *
673 * Finally, note that bfqg itself needs to be protected from
674 * destruction on the blkg_free of the original blkg (which
675 * invokes bfq_pd_free). We use an additional private
676 * refcounter for bfqg, to let it disappear only after no
677 * bfq_queue refers to it any longer.
678 */
679 blkg_path(bfqg_to_blkg(bfqg), bfqg->blkg_path, sizeof(bfqg->blkg_path));
Paolo Valenteea25da42017-04-19 08:48:24 -0600680 bic->blkcg_serial_nr = serial_nr;
681out:
682 rcu_read_unlock();
683}
684
685/**
686 * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
687 * @st: the service tree being flushed.
688 */
689static void bfq_flush_idle_tree(struct bfq_service_tree *st)
690{
691 struct bfq_entity *entity = st->first_idle;
692
693 for (; entity ; entity = st->first_idle)
694 __bfq_deactivate_entity(entity, false);
695}
696
697/**
698 * bfq_reparent_leaf_entity - move leaf entity to the root_group.
699 * @bfqd: the device data structure with the root group.
700 * @entity: the entity to move.
701 */
702static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
703 struct bfq_entity *entity)
704{
705 struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
706
707 bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
708}
709
710/**
711 * bfq_reparent_active_entities - move to the root group all active
712 * entities.
713 * @bfqd: the device data structure with the root group.
714 * @bfqg: the group to move from.
715 * @st: the service tree with the entities.
Paolo Valenteea25da42017-04-19 08:48:24 -0600716 */
717static void bfq_reparent_active_entities(struct bfq_data *bfqd,
718 struct bfq_group *bfqg,
719 struct bfq_service_tree *st)
720{
721 struct rb_root *active = &st->active;
722 struct bfq_entity *entity = NULL;
723
724 if (!RB_EMPTY_ROOT(&st->active))
725 entity = bfq_entity_of(rb_first(active));
726
727 for (; entity ; entity = bfq_entity_of(rb_first(active)))
728 bfq_reparent_leaf_entity(bfqd, entity);
729
730 if (bfqg->sched_data.in_service_entity)
731 bfq_reparent_leaf_entity(bfqd,
732 bfqg->sched_data.in_service_entity);
733}
734
735/**
736 * bfq_pd_offline - deactivate the entity associated with @pd,
737 * and reparent its children entities.
738 * @pd: descriptor of the policy going offline.
739 *
740 * blkio already grabs the queue_lock for us, so no need to use
741 * RCU-based magic
742 */
743void bfq_pd_offline(struct blkg_policy_data *pd)
744{
745 struct bfq_service_tree *st;
746 struct bfq_group *bfqg = pd_to_bfqg(pd);
747 struct bfq_data *bfqd = bfqg->bfqd;
748 struct bfq_entity *entity = bfqg->my_entity;
749 unsigned long flags;
750 int i;
751
752 if (!entity) /* root group */
753 return;
754
755 spin_lock_irqsave(&bfqd->lock, flags);
756 /*
757 * Empty all service_trees belonging to this group before
758 * deactivating the group itself.
759 */
760 for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
761 st = bfqg->sched_data.service_tree + i;
762
763 /*
764 * The idle tree may still contain bfq_queues belonging
765 * to exited task because they never migrated to a different
Paolo Valente8f9bebc2017-06-05 10:11:15 +0200766 * cgroup from the one being destroyed now.
Paolo Valenteea25da42017-04-19 08:48:24 -0600767 */
768 bfq_flush_idle_tree(st);
769
770 /*
771 * It may happen that some queues are still active
772 * (busy) upon group destruction (if the corresponding
773 * processes have been forced to terminate). We move
774 * all the leaf entities corresponding to these queues
775 * to the root_group.
776 * Also, it may happen that the group has an entity
777 * in service, which is disconnected from the active
778 * tree: it must be moved, too.
779 * There is no need to put the sync queues, as the
780 * scheduler has taken no reference.
781 */
782 bfq_reparent_active_entities(bfqd, bfqg, st);
783 }
784
785 __bfq_deactivate_entity(entity, false);
786 bfq_put_async_queues(bfqd, bfqg);
787
788 spin_unlock_irqrestore(&bfqd->lock, flags);
789 /*
790 * @blkg is going offline and will be ignored by
791 * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
792 * that they don't get lost. If IOs complete after this point, the
793 * stats for them will be lost. Oh well...
794 */
795 bfqg_stats_xfer_dead(bfqg);
796}
797
798void bfq_end_wr_async(struct bfq_data *bfqd)
799{
800 struct blkcg_gq *blkg;
801
802 list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) {
803 struct bfq_group *bfqg = blkg_to_bfqg(blkg);
804
805 bfq_end_wr_async_queues(bfqd, bfqg);
806 }
807 bfq_end_wr_async_queues(bfqd, bfqd->root_group);
808}
809
810static int bfq_io_show_weight(struct seq_file *sf, void *v)
811{
812 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
813 struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
814 unsigned int val = 0;
815
816 if (bfqgd)
817 val = bfqgd->weight;
818
819 seq_printf(sf, "%u\n", val);
820
821 return 0;
822}
823
824static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
825 struct cftype *cftype,
826 u64 val)
827{
828 struct blkcg *blkcg = css_to_blkcg(css);
829 struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
830 struct blkcg_gq *blkg;
831 int ret = -ERANGE;
832
833 if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
834 return ret;
835
836 ret = 0;
837 spin_lock_irq(&blkcg->lock);
838 bfqgd->weight = (unsigned short)val;
839 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
840 struct bfq_group *bfqg = blkg_to_bfqg(blkg);
841
842 if (!bfqg)
843 continue;
844 /*
845 * Setting the prio_changed flag of the entity
846 * to 1 with new_weight == weight would re-set
847 * the value of the weight to its ioprio mapping.
848 * Set the flag only if necessary.
849 */
850 if ((unsigned short)val != bfqg->entity.new_weight) {
851 bfqg->entity.new_weight = (unsigned short)val;
852 /*
853 * Make sure that the above new value has been
854 * stored in bfqg->entity.new_weight before
855 * setting the prio_changed flag. In fact,
856 * this flag may be read asynchronously (in
857 * critical sections protected by a different
858 * lock than that held here), and finding this
859 * flag set may cause the execution of the code
860 * for updating parameters whose value may
861 * depend also on bfqg->entity.new_weight (in
862 * __bfq_entity_update_weight_prio).
863 * This barrier makes sure that the new value
864 * of bfqg->entity.new_weight is correctly
865 * seen in that code.
866 */
867 smp_wmb();
868 bfqg->entity.prio_changed = 1;
869 }
870 }
871 spin_unlock_irq(&blkcg->lock);
872
873 return ret;
874}
875
876static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
877 char *buf, size_t nbytes,
878 loff_t off)
879{
880 u64 weight;
881 /* First unsigned long found in the file is used */
882 int ret = kstrtoull(strim(buf), 0, &weight);
883
884 if (ret)
885 return ret;
886
887 return bfq_io_set_weight_legacy(of_css(of), NULL, weight);
888}
889
890static int bfqg_print_stat(struct seq_file *sf, void *v)
891{
892 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
893 &blkcg_policy_bfq, seq_cft(sf)->private, false);
894 return 0;
895}
896
897static int bfqg_print_rwstat(struct seq_file *sf, void *v)
898{
899 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
900 &blkcg_policy_bfq, seq_cft(sf)->private, true);
901 return 0;
902}
903
904static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
905 struct blkg_policy_data *pd, int off)
906{
907 u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
908 &blkcg_policy_bfq, off);
909 return __blkg_prfill_u64(sf, pd, sum);
910}
911
912static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
913 struct blkg_policy_data *pd, int off)
914{
915 struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
916 &blkcg_policy_bfq,
917 off);
918 return __blkg_prfill_rwstat(sf, pd, &sum);
919}
920
921static int bfqg_print_stat_recursive(struct seq_file *sf, void *v)
922{
923 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
924 bfqg_prfill_stat_recursive, &blkcg_policy_bfq,
925 seq_cft(sf)->private, false);
926 return 0;
927}
928
929static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
930{
931 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
932 bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq,
933 seq_cft(sf)->private, true);
934 return 0;
935}
936
937static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
938 int off)
939{
940 u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
941
942 return __blkg_prfill_u64(sf, pd, sum >> 9);
943}
944
945static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
946{
947 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
948 bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false);
949 return 0;
950}
951
952static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
953 struct blkg_policy_data *pd, int off)
954{
955 struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
956 offsetof(struct blkcg_gq, stat_bytes));
957 u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
958 atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
959
960 return __blkg_prfill_u64(sf, pd, sum >> 9);
961}
962
963static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
964{
965 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
966 bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0,
967 false);
968 return 0;
969}
970
971static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
972 struct blkg_policy_data *pd, int off)
973{
974 struct bfq_group *bfqg = pd_to_bfqg(pd);
975 u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples);
976 u64 v = 0;
977
978 if (samples) {
979 v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum);
980 v = div64_u64(v, samples);
981 }
982 __blkg_prfill_u64(sf, pd, v);
983 return 0;
984}
985
986/* print avg_queue_size */
987static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
988{
989 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
990 bfqg_prfill_avg_queue_size, &blkcg_policy_bfq,
991 0, false);
992 return 0;
993}
994
995struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
996{
997 int ret;
998
999 ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq);
1000 if (ret)
1001 return NULL;
1002
1003 return blkg_to_bfqg(bfqd->queue->root_blkg);
1004}
1005
1006struct blkcg_policy blkcg_policy_bfq = {
1007 .dfl_cftypes = bfq_blkg_files,
1008 .legacy_cftypes = bfq_blkcg_legacy_files,
1009
1010 .cpd_alloc_fn = bfq_cpd_alloc,
1011 .cpd_init_fn = bfq_cpd_init,
1012 .cpd_bind_fn = bfq_cpd_init,
1013 .cpd_free_fn = bfq_cpd_free,
1014
1015 .pd_alloc_fn = bfq_pd_alloc,
1016 .pd_init_fn = bfq_pd_init,
1017 .pd_offline_fn = bfq_pd_offline,
1018 .pd_free_fn = bfq_pd_free,
1019 .pd_reset_stats_fn = bfq_pd_reset_stats,
1020};
1021
1022struct cftype bfq_blkcg_legacy_files[] = {
1023 {
1024 .name = "bfq.weight",
1025 .flags = CFTYPE_NOT_ON_ROOT,
1026 .seq_show = bfq_io_show_weight,
1027 .write_u64 = bfq_io_set_weight_legacy,
1028 },
1029
1030 /* statistics, covers only the tasks in the bfqg */
1031 {
1032 .name = "bfq.time",
1033 .private = offsetof(struct bfq_group, stats.time),
1034 .seq_show = bfqg_print_stat,
1035 },
1036 {
1037 .name = "bfq.sectors",
1038 .seq_show = bfqg_print_stat_sectors,
1039 },
1040 {
1041 .name = "bfq.io_service_bytes",
1042 .private = (unsigned long)&blkcg_policy_bfq,
1043 .seq_show = blkg_print_stat_bytes,
1044 },
1045 {
1046 .name = "bfq.io_serviced",
1047 .private = (unsigned long)&blkcg_policy_bfq,
1048 .seq_show = blkg_print_stat_ios,
1049 },
1050 {
1051 .name = "bfq.io_service_time",
1052 .private = offsetof(struct bfq_group, stats.service_time),
1053 .seq_show = bfqg_print_rwstat,
1054 },
1055 {
1056 .name = "bfq.io_wait_time",
1057 .private = offsetof(struct bfq_group, stats.wait_time),
1058 .seq_show = bfqg_print_rwstat,
1059 },
1060 {
1061 .name = "bfq.io_merged",
1062 .private = offsetof(struct bfq_group, stats.merged),
1063 .seq_show = bfqg_print_rwstat,
1064 },
1065 {
1066 .name = "bfq.io_queued",
1067 .private = offsetof(struct bfq_group, stats.queued),
1068 .seq_show = bfqg_print_rwstat,
1069 },
1070
1071 /* the same statictics which cover the bfqg and its descendants */
1072 {
1073 .name = "bfq.time_recursive",
1074 .private = offsetof(struct bfq_group, stats.time),
1075 .seq_show = bfqg_print_stat_recursive,
1076 },
1077 {
1078 .name = "bfq.sectors_recursive",
1079 .seq_show = bfqg_print_stat_sectors_recursive,
1080 },
1081 {
1082 .name = "bfq.io_service_bytes_recursive",
1083 .private = (unsigned long)&blkcg_policy_bfq,
1084 .seq_show = blkg_print_stat_bytes_recursive,
1085 },
1086 {
1087 .name = "bfq.io_serviced_recursive",
1088 .private = (unsigned long)&blkcg_policy_bfq,
1089 .seq_show = blkg_print_stat_ios_recursive,
1090 },
1091 {
1092 .name = "bfq.io_service_time_recursive",
1093 .private = offsetof(struct bfq_group, stats.service_time),
1094 .seq_show = bfqg_print_rwstat_recursive,
1095 },
1096 {
1097 .name = "bfq.io_wait_time_recursive",
1098 .private = offsetof(struct bfq_group, stats.wait_time),
1099 .seq_show = bfqg_print_rwstat_recursive,
1100 },
1101 {
1102 .name = "bfq.io_merged_recursive",
1103 .private = offsetof(struct bfq_group, stats.merged),
1104 .seq_show = bfqg_print_rwstat_recursive,
1105 },
1106 {
1107 .name = "bfq.io_queued_recursive",
1108 .private = offsetof(struct bfq_group, stats.queued),
1109 .seq_show = bfqg_print_rwstat_recursive,
1110 },
1111 {
1112 .name = "bfq.avg_queue_size",
1113 .seq_show = bfqg_print_avg_queue_size,
1114 },
1115 {
1116 .name = "bfq.group_wait_time",
1117 .private = offsetof(struct bfq_group, stats.group_wait_time),
1118 .seq_show = bfqg_print_stat,
1119 },
1120 {
1121 .name = "bfq.idle_time",
1122 .private = offsetof(struct bfq_group, stats.idle_time),
1123 .seq_show = bfqg_print_stat,
1124 },
1125 {
1126 .name = "bfq.empty_time",
1127 .private = offsetof(struct bfq_group, stats.empty_time),
1128 .seq_show = bfqg_print_stat,
1129 },
1130 {
1131 .name = "bfq.dequeue",
1132 .private = offsetof(struct bfq_group, stats.dequeue),
1133 .seq_show = bfqg_print_stat,
1134 },
1135 { } /* terminate */
1136};
1137
1138struct cftype bfq_blkg_files[] = {
1139 {
1140 .name = "bfq.weight",
1141 .flags = CFTYPE_NOT_ON_ROOT,
1142 .seq_show = bfq_io_show_weight,
1143 .write = bfq_io_set_weight,
1144 },
1145 {} /* terminate */
1146};
1147
1148#else /* CONFIG_BFQ_GROUP_IOSCHED */
1149
1150void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
1151 unsigned int op) { }
1152void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { }
1153void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { }
1154void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time,
1155 uint64_t io_start_time, unsigned int op) { }
1156void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
1157void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
1158void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }
1159void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
1160void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { }
1161
1162void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1163 struct bfq_group *bfqg) {}
1164
1165void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg)
1166{
1167 struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
1168
1169 entity->weight = entity->new_weight;
1170 entity->orig_weight = entity->new_weight;
1171 if (bfqq) {
1172 bfqq->ioprio = bfqq->new_ioprio;
1173 bfqq->ioprio_class = bfqq->new_ioprio_class;
1174 }
1175 entity->sched_data = &bfqg->sched_data;
1176}
1177
1178void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {}
1179
1180void bfq_end_wr_async(struct bfq_data *bfqd)
1181{
1182 bfq_end_wr_async_queues(bfqd, bfqd->root_group);
1183}
1184
1185struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, struct blkcg *blkcg)
1186{
1187 return bfqd->root_group;
1188}
1189
1190struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
1191{
1192 return bfqq->bfqd->root_group;
1193}
1194
1195struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
1196{
1197 struct bfq_group *bfqg;
1198 int i;
1199
1200 bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
1201 if (!bfqg)
1202 return NULL;
1203
1204 for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
1205 bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
1206
1207 return bfqg;
1208}
1209#endif /* CONFIG_BFQ_GROUP_IOSCHED */