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,
71 struct request *rq, struct io_context *ioc)
75 spin_lock_irq(q->queue_lock);
76 icq = ioc_lookup_icq(ioc, q);
77 spin_unlock_irq(q->queue_lock);
80 icq = ioc_create_icq(ioc, q, GFP_ATOMIC);
86 if (!blk_mq_sched_get_rq_priv(q, rq)) {
87 rq->rq_flags |= RQF_ELVPRIV;
88 get_io_context(icq->ioc);
95 static void blk_mq_sched_assign_ioc(struct request_queue *q,
96 struct request *rq, struct bio *bio)
98 struct io_context *ioc;
102 __blk_mq_sched_assign_ioc(q, rq, ioc);
105 struct request *blk_mq_sched_get_request(struct request_queue *q,
108 struct blk_mq_alloc_data *data)
110 struct elevator_queue *e = q->elevator;
111 struct blk_mq_hw_ctx *hctx;
112 struct blk_mq_ctx *ctx;
115 blk_queue_enter_live(q);
116 ctx = blk_mq_get_ctx(q);
117 hctx = blk_mq_map_queue(q, ctx->cpu);
119 blk_mq_set_alloc_data(data, q, data->flags, ctx, hctx);
122 data->flags |= BLK_MQ_REQ_INTERNAL;
125 * Flush requests are special and go directly to the
128 if (!op_is_flush(op) && e->type->ops.mq.get_request) {
129 rq = e->type->ops.mq.get_request(q, op, data);
131 rq->rq_flags |= RQF_QUEUED;
133 rq = __blk_mq_alloc_request(data, op);
135 rq = __blk_mq_alloc_request(data, op);
137 data->hctx->tags->rqs[rq->tag] = rq;
141 if (!op_is_flush(op)) {
143 if (e && e->type->icq_cache)
144 blk_mq_sched_assign_ioc(q, rq, bio);
146 data->hctx->queued++;
154 void blk_mq_sched_put_request(struct request *rq)
156 struct request_queue *q = rq->q;
157 struct elevator_queue *e = q->elevator;
159 if (rq->rq_flags & RQF_ELVPRIV) {
160 blk_mq_sched_put_rq_priv(rq->q, rq);
162 put_io_context(rq->elv.icq->ioc);
167 if ((rq->rq_flags & RQF_QUEUED) && e && e->type->ops.mq.put_request)
168 e->type->ops.mq.put_request(rq);
170 blk_mq_finish_request(rq);
173 void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
175 struct elevator_queue *e = hctx->queue->elevator;
178 if (unlikely(blk_mq_hctx_stopped(hctx)))
184 * If we have previous entries on our dispatch list, grab them first for
185 * more fair dispatch.
187 if (!list_empty_careful(&hctx->dispatch)) {
188 spin_lock(&hctx->lock);
189 if (!list_empty(&hctx->dispatch))
190 list_splice_init(&hctx->dispatch, &rq_list);
191 spin_unlock(&hctx->lock);
195 * Only ask the scheduler for requests, if we didn't have residual
196 * requests from the dispatch list. This is to avoid the case where
197 * we only ever dispatch a fraction of the requests available because
198 * of low device queue depth. Once we pull requests out of the IO
199 * scheduler, we can no longer merge or sort them. So it's best to
200 * leave them there for as long as we can. Mark the hw queue as
201 * needing a restart in that case.
203 if (!list_empty(&rq_list)) {
204 blk_mq_sched_mark_restart(hctx);
205 blk_mq_dispatch_rq_list(hctx, &rq_list);
206 } else if (!e || !e->type->ops.mq.dispatch_request) {
207 blk_mq_flush_busy_ctxs(hctx, &rq_list);
208 blk_mq_dispatch_rq_list(hctx, &rq_list);
213 rq = e->type->ops.mq.dispatch_request(hctx);
216 list_add(&rq->queuelist, &rq_list);
217 } while (blk_mq_dispatch_rq_list(hctx, &rq_list));
221 void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx,
222 struct list_head *rq_list,
223 struct request *(*get_rq)(struct blk_mq_hw_ctx *))
232 list_add_tail(&rq->queuelist, rq_list);
235 EXPORT_SYMBOL_GPL(blk_mq_sched_move_to_dispatch);
237 bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
238 struct request **merged_request)
242 switch (elv_merge(q, &rq, bio)) {
243 case ELEVATOR_BACK_MERGE:
244 if (!blk_mq_sched_allow_merge(q, rq, bio))
246 if (!bio_attempt_back_merge(q, rq, bio))
248 *merged_request = attempt_back_merge(q, rq);
249 if (!*merged_request)
250 elv_merged_request(q, rq, ELEVATOR_BACK_MERGE);
252 case ELEVATOR_FRONT_MERGE:
253 if (!blk_mq_sched_allow_merge(q, rq, bio))
255 if (!bio_attempt_front_merge(q, rq, bio))
257 *merged_request = attempt_front_merge(q, rq);
258 if (!*merged_request)
259 elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE);
265 EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
267 bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
269 struct elevator_queue *e = q->elevator;
271 if (e->type->ops.mq.bio_merge) {
272 struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
273 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
276 return e->type->ops.mq.bio_merge(hctx, bio);
282 bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq)
284 return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq);
286 EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge);
288 void blk_mq_sched_request_inserted(struct request *rq)
290 trace_block_rq_insert(rq->q, rq);
292 EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted);
294 static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
298 rq->rq_flags |= RQF_SORTED;
303 * If we already have a real request tag, send directly to
306 spin_lock(&hctx->lock);
307 list_add(&rq->queuelist, &hctx->dispatch);
308 spin_unlock(&hctx->lock);
312 static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
314 if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) {
315 clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
316 if (blk_mq_hctx_has_pending(hctx))
317 blk_mq_run_hw_queue(hctx, true);
321 void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx)
325 if (!(hctx->flags & BLK_MQ_F_TAG_SHARED))
326 blk_mq_sched_restart_hctx(hctx);
328 struct request_queue *q = hctx->queue;
330 if (!test_bit(QUEUE_FLAG_RESTART, &q->queue_flags))
333 clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags);
335 queue_for_each_hw_ctx(q, hctx, i)
336 blk_mq_sched_restart_hctx(hctx);
341 * Add flush/fua to the queue. If we fail getting a driver tag, then
342 * punt to the requeue list. Requeue will re-invoke us from a context
343 * that's safe to block from.
345 static void blk_mq_sched_insert_flush(struct blk_mq_hw_ctx *hctx,
346 struct request *rq, bool can_block)
348 if (blk_mq_get_driver_tag(rq, &hctx, can_block)) {
349 blk_insert_flush(rq);
350 blk_mq_run_hw_queue(hctx, true);
352 blk_mq_add_to_requeue_list(rq, true, true);
355 void blk_mq_sched_insert_request(struct request *rq, bool at_head,
356 bool run_queue, bool async, bool can_block)
358 struct request_queue *q = rq->q;
359 struct elevator_queue *e = q->elevator;
360 struct blk_mq_ctx *ctx = rq->mq_ctx;
361 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
363 if (rq->tag == -1 && op_is_flush(rq->cmd_flags)) {
364 blk_mq_sched_insert_flush(hctx, rq, can_block);
368 if (e && blk_mq_sched_bypass_insert(hctx, rq))
371 if (e && e->type->ops.mq.insert_requests) {
374 list_add(&rq->queuelist, &list);
375 e->type->ops.mq.insert_requests(hctx, &list, at_head);
377 spin_lock(&ctx->lock);
378 __blk_mq_insert_request(hctx, rq, at_head);
379 spin_unlock(&ctx->lock);
384 blk_mq_run_hw_queue(hctx, async);
387 void blk_mq_sched_insert_requests(struct request_queue *q,
388 struct blk_mq_ctx *ctx,
389 struct list_head *list, bool run_queue_async)
391 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
392 struct elevator_queue *e = hctx->queue->elevator;
395 struct request *rq, *next;
398 * We bypass requests that already have a driver tag assigned,
399 * which should only be flushes. Flushes are only ever inserted
400 * as single requests, so we shouldn't ever hit the
401 * WARN_ON_ONCE() below (but let's handle it just in case).
403 list_for_each_entry_safe(rq, next, list, queuelist) {
404 if (WARN_ON_ONCE(rq->tag != -1)) {
405 list_del_init(&rq->queuelist);
406 blk_mq_sched_bypass_insert(hctx, rq);
411 if (e && e->type->ops.mq.insert_requests)
412 e->type->ops.mq.insert_requests(hctx, list, false);
414 blk_mq_insert_requests(hctx, ctx, list);
416 blk_mq_run_hw_queue(hctx, run_queue_async);
419 static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
420 struct blk_mq_hw_ctx *hctx,
421 unsigned int hctx_idx)
423 if (hctx->sched_tags) {
424 blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx);
425 blk_mq_free_rq_map(hctx->sched_tags);
426 hctx->sched_tags = NULL;
430 int blk_mq_sched_setup(struct request_queue *q)
432 struct blk_mq_tag_set *set = q->tag_set;
433 struct blk_mq_hw_ctx *hctx;
437 * Default to 256, since we don't split into sync/async like the
438 * old code did. Additionally, this is a per-hw queue depth.
440 q->nr_requests = 2 * BLKDEV_MAX_RQ;
443 * We're switching to using an IO scheduler, so setup the hctx
444 * scheduler tags and switch the request map from the regular
445 * tags to scheduler tags. First allocate what we need, so we
446 * can safely fail and fallback, if needed.
449 queue_for_each_hw_ctx(q, hctx, i) {
450 hctx->sched_tags = blk_mq_alloc_rq_map(set, i, q->nr_requests, 0);
451 if (!hctx->sched_tags) {
455 ret = blk_mq_alloc_rqs(set, hctx->sched_tags, i, q->nr_requests);
461 * If we failed, free what we did allocate
464 queue_for_each_hw_ctx(q, hctx, i) {
465 if (!hctx->sched_tags)
467 blk_mq_sched_free_tags(set, hctx, i);
476 void blk_mq_sched_teardown(struct request_queue *q)
478 struct blk_mq_tag_set *set = q->tag_set;
479 struct blk_mq_hw_ctx *hctx;
482 queue_for_each_hw_ctx(q, hctx, i)
483 blk_mq_sched_free_tags(set, hctx, i);
486 int blk_mq_sched_init(struct request_queue *q)
490 #if defined(CONFIG_DEFAULT_SQ_NONE)
491 if (q->nr_hw_queues == 1)
494 #if defined(CONFIG_DEFAULT_MQ_NONE)
495 if (q->nr_hw_queues > 1)
499 mutex_lock(&q->sysfs_lock);
500 ret = elevator_init(q, NULL);
501 mutex_unlock(&q->sysfs_lock);