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)
242 ret = elv_merge(q, &rq, bio);
243 if (ret == ELEVATOR_BACK_MERGE) {
244 if (!blk_mq_sched_allow_merge(q, rq, bio))
246 if (bio_attempt_back_merge(q, rq, bio)) {
247 if (!attempt_back_merge(q, rq))
248 elv_merged_request(q, rq, ret);
251 } else if (ret == ELEVATOR_FRONT_MERGE) {
252 if (!blk_mq_sched_allow_merge(q, rq, bio))
254 if (bio_attempt_front_merge(q, rq, bio)) {
255 if (!attempt_front_merge(q, rq))
256 elv_merged_request(q, rq, ret);
263 EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
265 bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
267 struct elevator_queue *e = q->elevator;
269 if (e->type->ops.mq.bio_merge) {
270 struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
271 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
274 return e->type->ops.mq.bio_merge(hctx, bio);
280 bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq)
282 return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq);
284 EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge);
286 void blk_mq_sched_request_inserted(struct request *rq)
288 trace_block_rq_insert(rq->q, rq);
290 EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted);
292 bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx, struct request *rq)
295 rq->rq_flags |= RQF_SORTED;
300 * If we already have a real request tag, send directly to
303 spin_lock(&hctx->lock);
304 list_add(&rq->queuelist, &hctx->dispatch);
305 spin_unlock(&hctx->lock);
308 EXPORT_SYMBOL_GPL(blk_mq_sched_bypass_insert);
310 static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
312 if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) {
313 clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
314 if (blk_mq_hctx_has_pending(hctx))
315 blk_mq_run_hw_queue(hctx, true);
319 void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx)
323 if (!(hctx->flags & BLK_MQ_F_TAG_SHARED))
324 blk_mq_sched_restart_hctx(hctx);
326 struct request_queue *q = hctx->queue;
328 if (!test_bit(QUEUE_FLAG_RESTART, &q->queue_flags))
331 clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags);
333 queue_for_each_hw_ctx(q, hctx, i)
334 blk_mq_sched_restart_hctx(hctx);
339 * Add flush/fua to the queue. If we fail getting a driver tag, then
340 * punt to the requeue list. Requeue will re-invoke us from a context
341 * that's safe to block from.
343 static void blk_mq_sched_insert_flush(struct blk_mq_hw_ctx *hctx,
344 struct request *rq, bool can_block)
346 if (blk_mq_get_driver_tag(rq, &hctx, can_block)) {
347 blk_insert_flush(rq);
348 blk_mq_run_hw_queue(hctx, true);
350 blk_mq_add_to_requeue_list(rq, true, true);
353 void blk_mq_sched_insert_request(struct request *rq, bool at_head,
354 bool run_queue, bool async, bool can_block)
356 struct request_queue *q = rq->q;
357 struct elevator_queue *e = q->elevator;
358 struct blk_mq_ctx *ctx = rq->mq_ctx;
359 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
361 if (rq->tag == -1 && op_is_flush(rq->cmd_flags)) {
362 blk_mq_sched_insert_flush(hctx, rq, can_block);
366 if (e && e->type->ops.mq.insert_requests) {
369 list_add(&rq->queuelist, &list);
370 e->type->ops.mq.insert_requests(hctx, &list, at_head);
372 spin_lock(&ctx->lock);
373 __blk_mq_insert_request(hctx, rq, at_head);
374 spin_unlock(&ctx->lock);
378 blk_mq_run_hw_queue(hctx, async);
381 void blk_mq_sched_insert_requests(struct request_queue *q,
382 struct blk_mq_ctx *ctx,
383 struct list_head *list, bool run_queue_async)
385 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
386 struct elevator_queue *e = hctx->queue->elevator;
388 if (e && e->type->ops.mq.insert_requests)
389 e->type->ops.mq.insert_requests(hctx, list, false);
391 blk_mq_insert_requests(hctx, ctx, list);
393 blk_mq_run_hw_queue(hctx, run_queue_async);
396 static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
397 struct blk_mq_hw_ctx *hctx,
398 unsigned int hctx_idx)
400 if (hctx->sched_tags) {
401 blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx);
402 blk_mq_free_rq_map(hctx->sched_tags);
403 hctx->sched_tags = NULL;
407 int blk_mq_sched_setup(struct request_queue *q)
409 struct blk_mq_tag_set *set = q->tag_set;
410 struct blk_mq_hw_ctx *hctx;
414 * Default to 256, since we don't split into sync/async like the
415 * old code did. Additionally, this is a per-hw queue depth.
417 q->nr_requests = 2 * BLKDEV_MAX_RQ;
420 * We're switching to using an IO scheduler, so setup the hctx
421 * scheduler tags and switch the request map from the regular
422 * tags to scheduler tags. First allocate what we need, so we
423 * can safely fail and fallback, if needed.
426 queue_for_each_hw_ctx(q, hctx, i) {
427 hctx->sched_tags = blk_mq_alloc_rq_map(set, i, q->nr_requests, 0);
428 if (!hctx->sched_tags) {
432 ret = blk_mq_alloc_rqs(set, hctx->sched_tags, i, q->nr_requests);
438 * If we failed, free what we did allocate
441 queue_for_each_hw_ctx(q, hctx, i) {
442 if (!hctx->sched_tags)
444 blk_mq_sched_free_tags(set, hctx, i);
453 void blk_mq_sched_teardown(struct request_queue *q)
455 struct blk_mq_tag_set *set = q->tag_set;
456 struct blk_mq_hw_ctx *hctx;
459 queue_for_each_hw_ctx(q, hctx, i)
460 blk_mq_sched_free_tags(set, hctx, i);
463 int blk_mq_sched_init(struct request_queue *q)
467 #if defined(CONFIG_DEFAULT_SQ_NONE)
468 if (q->nr_hw_queues == 1)
471 #if defined(CONFIG_DEFAULT_MQ_NONE)
472 if (q->nr_hw_queues > 1)
476 mutex_lock(&q->sysfs_lock);
477 ret = elevator_init(q, NULL);
478 mutex_unlock(&q->sysfs_lock);