2 * blk-mq scheduling framework
4 * Copyright (C) 2016 Jens Axboe
6 #include <linux/kernel.h>
7 #include <linux/module.h>
8 #include <linux/blk-mq.h>
10 #include <trace/events/block.h>
14 #include "blk-mq-sched.h"
15 #include "blk-mq-tag.h"
18 void blk_mq_sched_free_hctx_data(struct request_queue *q,
19 void (*exit)(struct blk_mq_hw_ctx *))
21 struct blk_mq_hw_ctx *hctx;
24 queue_for_each_hw_ctx(q, hctx, i) {
25 if (exit && hctx->sched_data)
27 kfree(hctx->sched_data);
28 hctx->sched_data = NULL;
31 EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data);
33 int blk_mq_sched_init_hctx_data(struct request_queue *q, size_t size,
34 int (*init)(struct blk_mq_hw_ctx *),
35 void (*exit)(struct blk_mq_hw_ctx *))
37 struct blk_mq_hw_ctx *hctx;
41 queue_for_each_hw_ctx(q, hctx, i) {
42 hctx->sched_data = kmalloc_node(size, GFP_KERNEL, hctx->numa_node);
43 if (!hctx->sched_data) {
52 * We don't want to give exit() a partially
53 * initialized sched_data. init() must clean up
56 kfree(hctx->sched_data);
57 hctx->sched_data = NULL;
65 blk_mq_sched_free_hctx_data(q, exit);
68 EXPORT_SYMBOL_GPL(blk_mq_sched_init_hctx_data);
70 static void __blk_mq_sched_assign_ioc(struct request_queue *q,
73 struct io_context *ioc)
77 spin_lock_irq(q->queue_lock);
78 icq = ioc_lookup_icq(ioc, q);
79 spin_unlock_irq(q->queue_lock);
82 icq = ioc_create_icq(ioc, q, GFP_ATOMIC);
88 if (!blk_mq_sched_get_rq_priv(q, rq, bio)) {
89 rq->rq_flags |= RQF_ELVPRIV;
90 get_io_context(icq->ioc);
97 static void blk_mq_sched_assign_ioc(struct request_queue *q,
98 struct request *rq, struct bio *bio)
100 struct io_context *ioc;
104 __blk_mq_sched_assign_ioc(q, rq, bio, ioc);
107 struct request *blk_mq_sched_get_request(struct request_queue *q,
110 struct blk_mq_alloc_data *data)
112 struct elevator_queue *e = q->elevator;
115 blk_queue_enter_live(q);
117 if (likely(!data->ctx))
118 data->ctx = blk_mq_get_ctx(q);
119 if (likely(!data->hctx))
120 data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
123 data->flags |= BLK_MQ_REQ_INTERNAL;
126 * Flush requests are special and go directly to the
129 if (!op_is_flush(op) && e->type->ops.mq.get_request) {
130 rq = e->type->ops.mq.get_request(q, op, data);
132 rq->rq_flags |= RQF_QUEUED;
134 rq = __blk_mq_alloc_request(data, op);
136 rq = __blk_mq_alloc_request(data, op);
140 if (!op_is_flush(op)) {
142 if (e && e->type->icq_cache)
143 blk_mq_sched_assign_ioc(q, rq, bio);
145 data->hctx->queued++;
153 void blk_mq_sched_put_request(struct request *rq)
155 struct request_queue *q = rq->q;
156 struct elevator_queue *e = q->elevator;
158 if (rq->rq_flags & RQF_ELVPRIV) {
159 blk_mq_sched_put_rq_priv(rq->q, rq);
161 put_io_context(rq->elv.icq->ioc);
166 if ((rq->rq_flags & RQF_QUEUED) && e && e->type->ops.mq.put_request)
167 e->type->ops.mq.put_request(rq);
169 blk_mq_finish_request(rq);
172 void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
174 struct request_queue *q = hctx->queue;
175 struct elevator_queue *e = q->elevator;
176 const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request;
177 bool did_work = false;
180 if (unlikely(blk_mq_hctx_stopped(hctx)))
186 * If we have previous entries on our dispatch list, grab them first for
187 * more fair dispatch.
189 if (!list_empty_careful(&hctx->dispatch)) {
190 spin_lock(&hctx->lock);
191 if (!list_empty(&hctx->dispatch))
192 list_splice_init(&hctx->dispatch, &rq_list);
193 spin_unlock(&hctx->lock);
197 * Only ask the scheduler for requests, if we didn't have residual
198 * requests from the dispatch list. This is to avoid the case where
199 * we only ever dispatch a fraction of the requests available because
200 * of low device queue depth. Once we pull requests out of the IO
201 * scheduler, we can no longer merge or sort them. So it's best to
202 * leave them there for as long as we can. Mark the hw queue as
203 * needing a restart in that case.
205 if (!list_empty(&rq_list)) {
206 blk_mq_sched_mark_restart_hctx(hctx);
207 did_work = blk_mq_dispatch_rq_list(q, &rq_list);
208 } else if (!has_sched_dispatch) {
209 blk_mq_flush_busy_ctxs(hctx, &rq_list);
210 blk_mq_dispatch_rq_list(q, &rq_list);
214 * We want to dispatch from the scheduler if we had no work left
215 * on the dispatch list, OR if we did have work but weren't able
218 if (!did_work && has_sched_dispatch) {
222 rq = e->type->ops.mq.dispatch_request(hctx);
225 list_add(&rq->queuelist, &rq_list);
226 } while (blk_mq_dispatch_rq_list(q, &rq_list));
230 void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx,
231 struct list_head *rq_list,
232 struct request *(*get_rq)(struct blk_mq_hw_ctx *))
241 list_add_tail(&rq->queuelist, rq_list);
244 EXPORT_SYMBOL_GPL(blk_mq_sched_move_to_dispatch);
246 bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
247 struct request **merged_request)
251 switch (elv_merge(q, &rq, bio)) {
252 case ELEVATOR_BACK_MERGE:
253 if (!blk_mq_sched_allow_merge(q, rq, bio))
255 if (!bio_attempt_back_merge(q, rq, bio))
257 *merged_request = attempt_back_merge(q, rq);
258 if (!*merged_request)
259 elv_merged_request(q, rq, ELEVATOR_BACK_MERGE);
261 case ELEVATOR_FRONT_MERGE:
262 if (!blk_mq_sched_allow_merge(q, rq, bio))
264 if (!bio_attempt_front_merge(q, rq, bio))
266 *merged_request = attempt_front_merge(q, rq);
267 if (!*merged_request)
268 elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE);
274 EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
276 bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
278 struct elevator_queue *e = q->elevator;
280 if (e->type->ops.mq.bio_merge) {
281 struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
282 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
285 return e->type->ops.mq.bio_merge(hctx, bio);
291 bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq)
293 return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq);
295 EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge);
297 void blk_mq_sched_request_inserted(struct request *rq)
299 trace_block_rq_insert(rq->q, rq);
301 EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted);
303 static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
307 rq->rq_flags |= RQF_SORTED;
312 * If we already have a real request tag, send directly to
315 spin_lock(&hctx->lock);
316 list_add(&rq->queuelist, &hctx->dispatch);
317 spin_unlock(&hctx->lock);
321 static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
323 if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) {
324 clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
325 if (blk_mq_hctx_has_pending(hctx))
326 blk_mq_run_hw_queue(hctx, true);
330 void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx)
332 struct request_queue *q = hctx->queue;
335 if (test_bit(QUEUE_FLAG_RESTART, &q->queue_flags)) {
336 if (test_and_clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags)) {
337 queue_for_each_hw_ctx(q, hctx, i)
338 blk_mq_sched_restart_hctx(hctx);
341 blk_mq_sched_restart_hctx(hctx);
346 * Add flush/fua to the queue. If we fail getting a driver tag, then
347 * punt to the requeue list. Requeue will re-invoke us from a context
348 * that's safe to block from.
350 static void blk_mq_sched_insert_flush(struct blk_mq_hw_ctx *hctx,
351 struct request *rq, bool can_block)
353 if (blk_mq_get_driver_tag(rq, &hctx, can_block)) {
354 blk_insert_flush(rq);
355 blk_mq_run_hw_queue(hctx, true);
357 blk_mq_add_to_requeue_list(rq, false, true);
360 void blk_mq_sched_insert_request(struct request *rq, bool at_head,
361 bool run_queue, bool async, bool can_block)
363 struct request_queue *q = rq->q;
364 struct elevator_queue *e = q->elevator;
365 struct blk_mq_ctx *ctx = rq->mq_ctx;
366 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
368 if (rq->tag == -1 && op_is_flush(rq->cmd_flags)) {
369 blk_mq_sched_insert_flush(hctx, rq, can_block);
373 if (e && blk_mq_sched_bypass_insert(hctx, rq))
376 if (e && e->type->ops.mq.insert_requests) {
379 list_add(&rq->queuelist, &list);
380 e->type->ops.mq.insert_requests(hctx, &list, at_head);
382 spin_lock(&ctx->lock);
383 __blk_mq_insert_request(hctx, rq, at_head);
384 spin_unlock(&ctx->lock);
389 blk_mq_run_hw_queue(hctx, async);
392 void blk_mq_sched_insert_requests(struct request_queue *q,
393 struct blk_mq_ctx *ctx,
394 struct list_head *list, bool run_queue_async)
396 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
397 struct elevator_queue *e = hctx->queue->elevator;
400 struct request *rq, *next;
403 * We bypass requests that already have a driver tag assigned,
404 * which should only be flushes. Flushes are only ever inserted
405 * as single requests, so we shouldn't ever hit the
406 * WARN_ON_ONCE() below (but let's handle it just in case).
408 list_for_each_entry_safe(rq, next, list, queuelist) {
409 if (WARN_ON_ONCE(rq->tag != -1)) {
410 list_del_init(&rq->queuelist);
411 blk_mq_sched_bypass_insert(hctx, rq);
416 if (e && e->type->ops.mq.insert_requests)
417 e->type->ops.mq.insert_requests(hctx, list, false);
419 blk_mq_insert_requests(hctx, ctx, list);
421 blk_mq_run_hw_queue(hctx, run_queue_async);
424 static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
425 struct blk_mq_hw_ctx *hctx,
426 unsigned int hctx_idx)
428 if (hctx->sched_tags) {
429 blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx);
430 blk_mq_free_rq_map(hctx->sched_tags);
431 hctx->sched_tags = NULL;
435 static int blk_mq_sched_alloc_tags(struct request_queue *q,
436 struct blk_mq_hw_ctx *hctx,
437 unsigned int hctx_idx)
439 struct blk_mq_tag_set *set = q->tag_set;
442 hctx->sched_tags = blk_mq_alloc_rq_map(set, hctx_idx, q->nr_requests,
444 if (!hctx->sched_tags)
447 ret = blk_mq_alloc_rqs(set, hctx->sched_tags, hctx_idx, q->nr_requests);
449 blk_mq_sched_free_tags(set, hctx, hctx_idx);
454 void blk_mq_sched_teardown(struct request_queue *q)
456 struct blk_mq_tag_set *set = q->tag_set;
457 struct blk_mq_hw_ctx *hctx;
460 queue_for_each_hw_ctx(q, hctx, i)
461 blk_mq_sched_free_tags(set, hctx, i);
464 int blk_mq_sched_init_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
465 unsigned int hctx_idx)
467 struct elevator_queue *e = q->elevator;
472 return blk_mq_sched_alloc_tags(q, hctx, hctx_idx);
475 void blk_mq_sched_exit_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
476 unsigned int hctx_idx)
478 struct elevator_queue *e = q->elevator;
483 blk_mq_sched_free_tags(q->tag_set, hctx, hctx_idx);
486 int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
488 struct blk_mq_hw_ctx *hctx;
498 * Default to 256, since we don't split into sync/async like the
499 * old code did. Additionally, this is a per-hw queue depth.
501 q->nr_requests = 2 * BLKDEV_MAX_RQ;
503 queue_for_each_hw_ctx(q, hctx, i) {
504 ret = blk_mq_sched_alloc_tags(q, hctx, i);
509 ret = e->ops.mq.init_sched(q, e);
516 blk_mq_sched_teardown(q);
520 int blk_mq_sched_init(struct request_queue *q)
524 mutex_lock(&q->sysfs_lock);
525 ret = elevator_init(q, NULL);
526 mutex_unlock(&q->sysfs_lock);