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author | Bart Van Assche <bvanassche@acm.org> | 2023-07-21 20:27:30 +0300 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2023-07-25 05:13:12 +0300 |
commit | 65a558f66c308251e256317957b75d1e643c33c3 (patch) | |
tree | 995b5688f46d82885fc4aa6002b814a2206b40ad | |
parent | d42e2e3448a99c41c8489766eeb732d8d741d5be (diff) | |
download | linux-65a558f66c308251e256317957b75d1e643c33c3.tar.xz |
block: Improve performance for BLK_MQ_F_BLOCKING drivers
blk_mq_run_queue() runs the queue asynchronously if BLK_MQ_F_BLOCKING
has been set. This is suboptimal since running the queue asynchronously
is slower than running the queue synchronously. This patch modifies
blk_mq_run_queue() as follows if BLK_MQ_F_BLOCKING has been set:
- Run the queue synchronously if it is allowed to sleep.
- Run the queue asynchronously if it is not allowed to sleep.
Additionally, blk_mq_run_hw_queue(hctx, false) calls are modified into
blk_mq_run_hw_queue(hctx, hctx->flags & BLK_MQ_F_BLOCKING) if the caller
may be invoked from atomic context.
The following caller chains have been reviewed:
blk_mq_run_hw_queue(hctx, false)
blk_mq_get_tag() /* may sleep, hence the functions it calls may also sleep */
blk_execute_rq() /* may sleep */
blk_mq_run_hw_queues(q, async=false)
blk_freeze_queue_start() /* may sleep */
blk_mq_requeue_work() /* may sleep */
scsi_kick_queue()
scsi_requeue_run_queue() /* may sleep */
scsi_run_host_queues()
scsi_ioctl_reset() /* may sleep */
blk_mq_insert_requests(hctx, ctx, list, run_queue_async=false)
blk_mq_dispatch_plug_list(plug, from_sched=false)
blk_mq_flush_plug_list(plug, from_schedule=false)
__blk_flush_plug(plug, from_schedule=false)
blk_add_rq_to_plug()
blk_mq_submit_bio() /* may sleep if REQ_NOWAIT has not been set */
blk_mq_plug_issue_direct()
blk_mq_flush_plug_list() /* see above */
blk_mq_dispatch_plug_list(plug, from_sched=false)
blk_mq_flush_plug_list() /* see above */
blk_mq_try_issue_directly()
blk_mq_submit_bio() /* may sleep if REQ_NOWAIT has not been set */
blk_mq_try_issue_list_directly(hctx, list)
blk_mq_insert_requests() /* see above */
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230721172731.955724-4-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r-- | block/blk-mq.c | 16 | ||||
-rw-r--r-- | drivers/scsi/scsi_lib.c | 3 |
2 files changed, 12 insertions, 7 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index d98654869615..687ec3f4f10d 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1323,7 +1323,7 @@ void blk_execute_rq_nowait(struct request *rq, bool at_head) } blk_mq_insert_request(rq, at_head ? BLK_MQ_INSERT_AT_HEAD : 0); - blk_mq_run_hw_queue(hctx, false); + blk_mq_run_hw_queue(hctx, hctx->flags & BLK_MQ_F_BLOCKING); } EXPORT_SYMBOL_GPL(blk_execute_rq_nowait); @@ -2222,6 +2222,8 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async) */ WARN_ON_ONCE(!async && in_interrupt()); + might_sleep_if(!async && hctx->flags & BLK_MQ_F_BLOCKING); + /* * When queue is quiesced, we may be switching io scheduler, or * updating nr_hw_queues, or other things, and we can't run queue @@ -2237,8 +2239,7 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async) if (!need_run) return; - if (async || (hctx->flags & BLK_MQ_F_BLOCKING) || - !cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask)) { + if (async || !cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask)) { blk_mq_delay_run_hw_queue(hctx, 0); return; } @@ -2373,7 +2374,7 @@ void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx) { clear_bit(BLK_MQ_S_STOPPED, &hctx->state); - blk_mq_run_hw_queue(hctx, false); + blk_mq_run_hw_queue(hctx, hctx->flags & BLK_MQ_F_BLOCKING); } EXPORT_SYMBOL(blk_mq_start_hw_queue); @@ -2403,7 +2404,8 @@ void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async) unsigned long i; queue_for_each_hw_ctx(q, hctx, i) - blk_mq_start_stopped_hw_queue(hctx, async); + blk_mq_start_stopped_hw_queue(hctx, async || + (hctx->flags & BLK_MQ_F_BLOCKING)); } EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues); @@ -2461,6 +2463,8 @@ static void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, list_for_each_entry(rq, list, queuelist) { BUG_ON(rq->mq_ctx != ctx); trace_block_rq_insert(rq); + if (rq->cmd_flags & REQ_NOWAIT) + run_queue_async = true; } spin_lock(&ctx->lock); @@ -2621,7 +2625,7 @@ static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, if ((rq->rq_flags & RQF_USE_SCHED) || !blk_mq_get_budget_and_tag(rq)) { blk_mq_insert_request(rq, 0); - blk_mq_run_hw_queue(hctx, false); + blk_mq_run_hw_queue(hctx, rq->cmd_flags & REQ_NOWAIT); return; } diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index d4c514ab9fe8..59176946ab56 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -335,7 +335,8 @@ static void scsi_single_lun_run(struct scsi_device *current_sdev) * but in most cases, we will be first. Ideally, each LU on the * target would get some limited time or requests on the target. */ - blk_mq_run_hw_queues(current_sdev->request_queue, false); + blk_mq_run_hw_queues(current_sdev->request_queue, + shost->queuecommand_may_block); spin_lock_irqsave(shost->host_lock, flags); if (!starget->starget_sdev_user) |