summaryrefslogtreecommitdiff
path: root/block/blk-mq.c
diff options
context:
space:
mode:
authorBart Van Assche <bvanassche@acm.org>2023-07-21 10:27:30 -0700
committerJens Axboe <axboe@kernel.dk>2023-07-24 20:13:12 -0600
commit65a558f66c308251e256317957b75d1e643c33c3 (patch)
tree995b5688f46d82885fc4aa6002b814a2206b40ad /block/blk-mq.c
parentd42e2e3448a99c41c8489766eeb732d8d741d5be (diff)
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>
Diffstat (limited to 'block/blk-mq.c')
-rw-r--r--block/blk-mq.c16
1 files changed, 10 insertions, 6 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;
}