X-Git-Url: http://git.monstr.eu/?a=blobdiff_plain;f=block%2Fblk-mq-sched.c;h=0f006cabfd914866a3b328b0c8f4ca31e207c9c5;hb=HEAD;hp=a4f7c101b53b28cbeceb4edac405301bf209e35e;hpb=98586bd6dce3690d8ae8d8561383d9ecc715e3c2;p=linux-2.6-microblaze.git diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index a4f7c101b53b..451a2c1f1f32 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -6,7 +6,6 @@ */ #include #include -#include #include #include @@ -15,12 +14,10 @@ #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. For shared queues, maintain - * a count of how many hardware queues are marked for restart. + * Mark a hardware queue as needing a restart. */ void blk_mq_sched_mark_restart_hctx(struct blk_mq_hw_ctx *hctx) { @@ -82,7 +79,7 @@ dispatch: /* * 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() returns BLK_STS_NO_RESOURCE. + * 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. @@ -210,7 +207,7 @@ static struct blk_mq_ctx *blk_mq_next_ctx(struct blk_mq_hw_ctx *hctx, /* * 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() returns BLK_STS_NO_RESOURCE. + * 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. @@ -272,9 +269,7 @@ static int blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx) 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; + bool need_dispatch = false; LIST_HEAD(rq_list); /* @@ -303,23 +298,22 @@ static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) */ 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); + if (!blk_mq_dispatch_rq_list(hctx, &rq_list, 0)) + return 0; + need_dispatch = true; } else { - blk_mq_flush_busy_ctxs(hctx, &rq_list); - blk_mq_dispatch_rq_list(hctx, &rq_list, 0); + need_dispatch = hctx->dispatch_busy; } - return ret; + if (hctx->queue->elevator) + return blk_mq_do_dispatch_sched(hctx); + + /* dequeue request one by one from sw queue if queue is busy */ + if (need_dispatch) + return blk_mq_do_dispatch_ctx(hctx); + blk_mq_flush_busy_ctxs(hctx, &rq_list); + blk_mq_dispatch_rq_list(hctx, &rq_list, 0); + return 0; } void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) @@ -330,8 +324,6 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) 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. @@ -385,116 +377,6 @@ bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq, } 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) @@ -555,6 +437,7 @@ static int blk_mq_init_sched_shared_tags(struct request_queue *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; @@ -563,13 +446,6 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e) unsigned long i; int ret; - if (!e) { - blk_queue_flag_clear(QUEUE_FLAG_SQ_SCHED, q); - q->elevator = NULL; - q->nr_requests = q->tag_set->queue_depth; - return 0; - } - /* * 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.