Author | Tokens | Token Proportion | Commits | Commit Proportion |
---|---|---|---|---|
Ming Lei | 835 | 33.74% | 31 | 23.85% |
Jens Axboe | 759 | 30.67% | 34 | 26.15% |
Omar Sandoval | 273 | 11.03% | 11 | 8.46% |
John Garry | 194 | 7.84% | 7 | 5.38% |
Salman Qazi | 122 | 4.93% | 1 | 0.77% |
Arnaldo Carvalho de Melo | 50 | 2.02% | 2 | 1.54% |
Shin'ichiro Kawasaki | 35 | 1.41% | 1 | 0.77% |
Bart Van Assche | 33 | 1.33% | 4 | 3.08% |
Jan Kara | 22 | 0.89% | 3 | 2.31% |
Doug Anderson | 21 | 0.85% | 1 | 0.77% |
Tejun Heo | 19 | 0.77% | 5 | 3.85% |
Baolin Wang | 18 | 0.73% | 2 | 1.54% |
Christoph Hellwig | 17 | 0.69% | 4 | 3.08% |
Damien Le Moal | 12 | 0.48% | 2 | 1.54% |
Luis R. Rodriguez | 8 | 0.32% | 1 | 0.77% |
Waiman Long | 8 | 0.32% | 1 | 0.77% |
Mike Snitzer | 8 | 0.32% | 1 | 0.77% |
Lei Ming | 7 | 0.28% | 1 | 0.77% |
Linus Torvalds (pre-git) | 7 | 0.28% | 3 | 2.31% |
Neil Brown | 5 | 0.20% | 1 | 0.77% |
Divyesh Shah | 4 | 0.16% | 1 | 0.77% |
Andrew Morton | 4 | 0.16% | 2 | 1.54% |
KeMeng Shi | 3 | 0.12% | 2 | 1.54% |
Sami Tolvanen | 2 | 0.08% | 1 | 0.77% |
Sagi Grimberg | 2 | 0.08% | 1 | 0.77% |
Pavel Begunkov | 2 | 0.08% | 2 | 1.54% |
Jinlong Chen | 1 | 0.04% | 1 | 0.77% |
Al Viro | 1 | 0.04% | 1 | 0.77% |
zhengbin | 1 | 0.04% | 1 | 0.77% |
Li Zefan | 1 | 0.04% | 1 | 0.77% |
Xianting Tian | 1 | 0.04% | 1 | 0.77% |
Total | 2475 | 130 |
// SPDX-License-Identifier: GPL-2.0 /* * blk-mq scheduling framework * * Copyright (C) 2016 Jens Axboe */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/blk-mq.h> #include <linux/list_sort.h> #include <trace/events/block.h> #include "blk.h" #include "blk-mq.h" #include "blk-mq-debugfs.h" #include "blk-mq-sched.h" #include "blk-mq-tag.h" #include "blk-wbt.h" /* * Mark a hardware queue as needing a restart. */ void blk_mq_sched_mark_restart_hctx(struct blk_mq_hw_ctx *hctx) { if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) return; set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state); } EXPORT_SYMBOL_GPL(blk_mq_sched_mark_restart_hctx); void __blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx) { clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state); /* * Order clearing SCHED_RESTART and list_empty_careful(&hctx->dispatch) * in blk_mq_run_hw_queue(). Its pair is the barrier in * blk_mq_dispatch_rq_list(). So dispatch code won't see SCHED_RESTART, * meantime new request added to hctx->dispatch is missed to check in * blk_mq_run_hw_queue(). */ smp_mb(); blk_mq_run_hw_queue(hctx, true); } static int sched_rq_cmp(void *priv, const struct list_head *a, const struct list_head *b) { struct request *rqa = container_of(a, struct request, queuelist); struct request *rqb = container_of(b, struct request, queuelist); return rqa->mq_hctx > rqb->mq_hctx; } static bool blk_mq_dispatch_hctx_list(struct list_head *rq_list) { struct blk_mq_hw_ctx *hctx = list_first_entry(rq_list, struct request, queuelist)->mq_hctx; struct request *rq; LIST_HEAD(hctx_list); unsigned int count = 0; list_for_each_entry(rq, rq_list, queuelist) { if (rq->mq_hctx != hctx) { list_cut_before(&hctx_list, rq_list, &rq->queuelist); goto dispatch; } count++; } list_splice_tail_init(rq_list, &hctx_list); dispatch: return blk_mq_dispatch_rq_list(hctx, &hctx_list, count); } #define BLK_MQ_BUDGET_DELAY 3 /* ms units */ /* * Only SCSI implements .get_budget and .put_budget, and SCSI restarts * its queue by itself in its completion handler, so we don't need to * restart queue if .get_budget() fails to get the budget. * * Returns -EAGAIN if hctx->dispatch was found non-empty and run_work has to * be run again. This is necessary to avoid starving flushes. */ static int __blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx) { struct request_queue *q = hctx->queue; struct elevator_queue *e = q->elevator; bool multi_hctxs = false, run_queue = false; bool dispatched = false, busy = false; unsigned int max_dispatch; LIST_HEAD(rq_list); int count = 0; if (hctx->dispatch_busy) max_dispatch = 1; else max_dispatch = hctx->queue->nr_requests; do { struct request *rq; int budget_token; if (e->type->ops.has_work && !e->type->ops.has_work(hctx)) break; if (!list_empty_careful(&hctx->dispatch)) { busy = true; break; } budget_token = blk_mq_get_dispatch_budget(q); if (budget_token < 0) break; rq = e->type->ops.dispatch_request(hctx); if (!rq) { blk_mq_put_dispatch_budget(q, budget_token); /* * We're releasing without dispatching. Holding the * budget could have blocked any "hctx"s with the * same queue and if we didn't dispatch then there's * no guarantee anyone will kick the queue. Kick it * ourselves. */ run_queue = true; break; } blk_mq_set_rq_budget_token(rq, budget_token); /* * Now this rq owns the budget which has to be released * if this rq won't be queued to driver via .queue_rq() * in blk_mq_dispatch_rq_list(). */ list_add_tail(&rq->queuelist, &rq_list); count++; if (rq->mq_hctx != hctx) multi_hctxs = true; /* * If we cannot get tag for the request, stop dequeueing * requests from the IO scheduler. We are unlikely to be able * to submit them anyway and it creates false impression for * scheduling heuristics that the device can take more IO. */ if (!blk_mq_get_driver_tag(rq)) break; } while (count < max_dispatch); if (!count) { if (run_queue) blk_mq_delay_run_hw_queues(q, BLK_MQ_BUDGET_DELAY); } else if (multi_hctxs) { /* * Requests from different hctx may be dequeued from some * schedulers, such as bfq and deadline. * * Sort the requests in the list according to their hctx, * dispatch batching requests from same hctx at a time. */ list_sort(NULL, &rq_list, sched_rq_cmp); do { dispatched |= blk_mq_dispatch_hctx_list(&rq_list); } while (!list_empty(&rq_list)); } else { dispatched = blk_mq_dispatch_rq_list(hctx, &rq_list, count); } if (busy) return -EAGAIN; return !!dispatched; } static int blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx) { unsigned long end = jiffies + HZ; int ret; do { ret = __blk_mq_do_dispatch_sched(hctx); if (ret != 1) break; if (need_resched() || time_is_before_jiffies(end)) { blk_mq_delay_run_hw_queue(hctx, 0); break; } } while (1); return ret; } static struct blk_mq_ctx *blk_mq_next_ctx(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx) { unsigned short idx = ctx->index_hw[hctx->type]; if (++idx == hctx->nr_ctx) idx = 0; return hctx->ctxs[idx]; } /* * Only SCSI implements .get_budget and .put_budget, and SCSI restarts * its queue by itself in its completion handler, so we don't need to * restart queue if .get_budget() fails to get the budget. * * Returns -EAGAIN if hctx->dispatch was found non-empty and run_work has to * be run again. This is necessary to avoid starving flushes. */ static int blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx) { struct request_queue *q = hctx->queue; LIST_HEAD(rq_list); struct blk_mq_ctx *ctx = READ_ONCE(hctx->dispatch_from); int ret = 0; struct request *rq; do { int budget_token; if (!list_empty_careful(&hctx->dispatch)) { ret = -EAGAIN; break; } if (!sbitmap_any_bit_set(&hctx->ctx_map)) break; budget_token = blk_mq_get_dispatch_budget(q); if (budget_token < 0) break; rq = blk_mq_dequeue_from_ctx(hctx, ctx); if (!rq) { blk_mq_put_dispatch_budget(q, budget_token); /* * We're releasing without dispatching. Holding the * budget could have blocked any "hctx"s with the * same queue and if we didn't dispatch then there's * no guarantee anyone will kick the queue. Kick it * ourselves. */ blk_mq_delay_run_hw_queues(q, BLK_MQ_BUDGET_DELAY); break; } blk_mq_set_rq_budget_token(rq, budget_token); /* * Now this rq owns the budget which has to be released * if this rq won't be queued to driver via .queue_rq() * in blk_mq_dispatch_rq_list(). */ list_add(&rq->queuelist, &rq_list); /* round robin for fair dispatch */ ctx = blk_mq_next_ctx(hctx, rq->mq_ctx); } while (blk_mq_dispatch_rq_list(rq->mq_hctx, &rq_list, 1)); WRITE_ONCE(hctx->dispatch_from, ctx); return ret; } static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) { struct request_queue *q = hctx->queue; const bool has_sched = q->elevator; int ret = 0; LIST_HEAD(rq_list); /* * If we have previous entries on our dispatch list, grab them first for * more fair dispatch. */ if (!list_empty_careful(&hctx->dispatch)) { spin_lock(&hctx->lock); if (!list_empty(&hctx->dispatch)) list_splice_init(&hctx->dispatch, &rq_list); spin_unlock(&hctx->lock); } /* * Only ask the scheduler for requests, if we didn't have residual * requests from the dispatch list. This is to avoid the case where * we only ever dispatch a fraction of the requests available because * of low device queue depth. Once we pull requests out of the IO * scheduler, we can no longer merge or sort them. So it's best to * leave them there for as long as we can. Mark the hw queue as * needing a restart in that case. * * We want to dispatch from the scheduler if there was nothing * on the dispatch list or we were able to dispatch from the * dispatch list. */ if (!list_empty(&rq_list)) { blk_mq_sched_mark_restart_hctx(hctx); if (blk_mq_dispatch_rq_list(hctx, &rq_list, 0)) { if (has_sched) ret = blk_mq_do_dispatch_sched(hctx); else ret = blk_mq_do_dispatch_ctx(hctx); } } else if (has_sched) { ret = blk_mq_do_dispatch_sched(hctx); } else if (hctx->dispatch_busy) { /* dequeue request one by one from sw queue if queue is busy */ ret = blk_mq_do_dispatch_ctx(hctx); } else { blk_mq_flush_busy_ctxs(hctx, &rq_list); blk_mq_dispatch_rq_list(hctx, &rq_list, 0); } return ret; } void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) { struct request_queue *q = hctx->queue; /* RCU or SRCU read lock is needed before checking quiesced flag */ if (unlikely(blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q))) return; hctx->run++; /* * A return of -EAGAIN is an indication that hctx->dispatch is not * empty and we must run again in order to avoid starving flushes. */ if (__blk_mq_sched_dispatch_requests(hctx) == -EAGAIN) { if (__blk_mq_sched_dispatch_requests(hctx) == -EAGAIN) blk_mq_run_hw_queue(hctx, true); } } bool blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio, unsigned int nr_segs) { struct elevator_queue *e = q->elevator; struct blk_mq_ctx *ctx; struct blk_mq_hw_ctx *hctx; bool ret = false; enum hctx_type type; if (e && e->type->ops.bio_merge) { ret = e->type->ops.bio_merge(q, bio, nr_segs); goto out_put; } ctx = blk_mq_get_ctx(q); hctx = blk_mq_map_queue(q, bio->bi_opf, ctx); type = hctx->type; if (!(hctx->flags & BLK_MQ_F_SHOULD_MERGE) || list_empty_careful(&ctx->rq_lists[type])) goto out_put; /* default per sw-queue merge */ spin_lock(&ctx->lock); /* * Reverse check our software queue for entries that we could * potentially merge with. Currently includes a hand-wavy stop * count of 8, to not spend too much time checking for merges. */ if (blk_bio_list_merge(q, &ctx->rq_lists[type], bio, nr_segs)) ret = true; spin_unlock(&ctx->lock); out_put: return ret; } bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq, struct list_head *free) { return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq, free); } EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge); static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx, struct request *rq) { /* * dispatch flush and passthrough rq directly * * passthrough request has to be added to hctx->dispatch directly. * For some reason, device may be in one situation which can't * handle FS request, so STS_RESOURCE is always returned and the * FS request will be added to hctx->dispatch. However passthrough * request may be required at that time for fixing the problem. If * passthrough request is added to scheduler queue, there isn't any * chance to dispatch it given we prioritize requests in hctx->dispatch. */ if ((rq->rq_flags & RQF_FLUSH_SEQ) || blk_rq_is_passthrough(rq)) return true; return false; } void blk_mq_sched_insert_request(struct request *rq, bool at_head, bool run_queue, bool async) { struct request_queue *q = rq->q; struct elevator_queue *e = q->elevator; struct blk_mq_ctx *ctx = rq->mq_ctx; struct blk_mq_hw_ctx *hctx = rq->mq_hctx; WARN_ON(e && (rq->tag != BLK_MQ_NO_TAG)); if (blk_mq_sched_bypass_insert(hctx, rq)) { /* * Firstly normal IO request is inserted to scheduler queue or * sw queue, meantime we add flush request to dispatch queue( * hctx->dispatch) directly and there is at most one in-flight * flush request for each hw queue, so it doesn't matter to add * flush request to tail or front of the dispatch queue. * * Secondly in case of NCQ, flush request belongs to non-NCQ * command, and queueing it will fail when there is any * in-flight normal IO request(NCQ command). When adding flush * rq to the front of hctx->dispatch, it is easier to introduce * extra time to flush rq's latency because of S_SCHED_RESTART * compared with adding to the tail of dispatch queue, then * chance of flush merge is increased, and less flush requests * will be issued to controller. It is observed that ~10% time * is saved in blktests block/004 on disk attached to AHCI/NCQ * drive when adding flush rq to the front of hctx->dispatch. * * Simply queue flush rq to the front of hctx->dispatch so that * intensive flush workloads can benefit in case of NCQ HW. */ at_head = (rq->rq_flags & RQF_FLUSH_SEQ) ? true : at_head; blk_mq_request_bypass_insert(rq, at_head, false); goto run; } if (e) { LIST_HEAD(list); list_add(&rq->queuelist, &list); e->type->ops.insert_requests(hctx, &list, at_head); } else { spin_lock(&ctx->lock); __blk_mq_insert_request(hctx, rq, at_head); spin_unlock(&ctx->lock); } run: if (run_queue) blk_mq_run_hw_queue(hctx, async); } void blk_mq_sched_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx, struct list_head *list, bool run_queue_async) { struct elevator_queue *e; struct request_queue *q = hctx->queue; /* * blk_mq_sched_insert_requests() is called from flush plug * context only, and hold one usage counter to prevent queue * from being released. */ percpu_ref_get(&q->q_usage_counter); e = hctx->queue->elevator; if (e) { e->type->ops.insert_requests(hctx, list, false); } else { /* * try to issue requests directly if the hw queue isn't * busy in case of 'none' scheduler, and this way may save * us one extra enqueue & dequeue to sw queue. */ if (!hctx->dispatch_busy && !run_queue_async) { blk_mq_run_dispatch_ops(hctx->queue, blk_mq_try_issue_list_directly(hctx, list)); if (list_empty(list)) goto out; } blk_mq_insert_requests(hctx, ctx, list); } blk_mq_run_hw_queue(hctx, run_queue_async); out: percpu_ref_put(&q->q_usage_counter); } static int blk_mq_sched_alloc_map_and_rqs(struct request_queue *q, struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx) { if (blk_mq_is_shared_tags(q->tag_set->flags)) { hctx->sched_tags = q->sched_shared_tags; return 0; } hctx->sched_tags = blk_mq_alloc_map_and_rqs(q->tag_set, hctx_idx, q->nr_requests); if (!hctx->sched_tags) return -ENOMEM; return 0; } static void blk_mq_exit_sched_shared_tags(struct request_queue *queue) { blk_mq_free_rq_map(queue->sched_shared_tags); queue->sched_shared_tags = NULL; } /* called in queue's release handler, tagset has gone away */ static void blk_mq_sched_tags_teardown(struct request_queue *q, unsigned int flags) { struct blk_mq_hw_ctx *hctx; unsigned long i; queue_for_each_hw_ctx(q, hctx, i) { if (hctx->sched_tags) { if (!blk_mq_is_shared_tags(flags)) blk_mq_free_rq_map(hctx->sched_tags); hctx->sched_tags = NULL; } } if (blk_mq_is_shared_tags(flags)) blk_mq_exit_sched_shared_tags(q); } static int blk_mq_init_sched_shared_tags(struct request_queue *queue) { struct blk_mq_tag_set *set = queue->tag_set; /* * Set initial depth at max so that we don't need to reallocate for * updating nr_requests. */ queue->sched_shared_tags = blk_mq_alloc_map_and_rqs(set, BLK_MQ_NO_HCTX_IDX, MAX_SCHED_RQ); if (!queue->sched_shared_tags) return -ENOMEM; blk_mq_tag_update_sched_shared_tags(queue); return 0; } /* caller must have a reference to @e, will grab another one if successful */ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e) { unsigned int flags = q->tag_set->flags; struct blk_mq_hw_ctx *hctx; struct elevator_queue *eq; unsigned long i; int ret; /* * Default to double of smaller one between hw queue_depth and 128, * since we don't split into sync/async like the old code did. * Additionally, this is a per-hw queue depth. */ q->nr_requests = 2 * min_t(unsigned int, q->tag_set->queue_depth, BLKDEV_DEFAULT_RQ); if (blk_mq_is_shared_tags(flags)) { ret = blk_mq_init_sched_shared_tags(q); if (ret) return ret; } queue_for_each_hw_ctx(q, hctx, i) { ret = blk_mq_sched_alloc_map_and_rqs(q, hctx, i); if (ret) goto err_free_map_and_rqs; } ret = e->ops.init_sched(q, e); if (ret) goto err_free_map_and_rqs; mutex_lock(&q->debugfs_mutex); blk_mq_debugfs_register_sched(q); mutex_unlock(&q->debugfs_mutex); queue_for_each_hw_ctx(q, hctx, i) { if (e->ops.init_hctx) { ret = e->ops.init_hctx(hctx, i); if (ret) { eq = q->elevator; blk_mq_sched_free_rqs(q); blk_mq_exit_sched(q, eq); kobject_put(&eq->kobj); return ret; } } mutex_lock(&q->debugfs_mutex); blk_mq_debugfs_register_sched_hctx(q, hctx); mutex_unlock(&q->debugfs_mutex); } return 0; err_free_map_and_rqs: blk_mq_sched_free_rqs(q); blk_mq_sched_tags_teardown(q, flags); q->elevator = NULL; return ret; } /* * called in either blk_queue_cleanup or elevator_switch, tagset * is required for freeing requests */ void blk_mq_sched_free_rqs(struct request_queue *q) { struct blk_mq_hw_ctx *hctx; unsigned long i; if (blk_mq_is_shared_tags(q->tag_set->flags)) { blk_mq_free_rqs(q->tag_set, q->sched_shared_tags, BLK_MQ_NO_HCTX_IDX); } else { queue_for_each_hw_ctx(q, hctx, i) { if (hctx->sched_tags) blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i); } } } void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e) { struct blk_mq_hw_ctx *hctx; unsigned long i; unsigned int flags = 0; queue_for_each_hw_ctx(q, hctx, i) { mutex_lock(&q->debugfs_mutex); blk_mq_debugfs_unregister_sched_hctx(hctx); mutex_unlock(&q->debugfs_mutex); if (e->type->ops.exit_hctx && hctx->sched_data) { e->type->ops.exit_hctx(hctx, i); hctx->sched_data = NULL; } flags = hctx->flags; } mutex_lock(&q->debugfs_mutex); blk_mq_debugfs_unregister_sched(q); mutex_unlock(&q->debugfs_mutex); if (e->type->ops.exit_sched) e->type->ops.exit_sched(e); blk_mq_sched_tags_teardown(q, flags); q->elevator = NULL; }
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