From 9bf9f8b09de63b57c39968491ae9301b8114a43d Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 8 Jul 2015 16:08:24 -0400 Subject: [PATCH] Revert "dm: only run the queue on completion if congested or no requests pending" commit 621739b00e16ca2d80411dc9b111cb15b91f3ba9 upstream. This reverts commit 9a0e609e3fd8a95c96629b9fbde6b8c5b9a1456a. (Resolved a conflict during revert due to commit bfebd1cdb4 that came after) This revert is motivated by a couple failure reports on request-based DM multipath testbeds: 1) Netapp reported that their multipath fault injection test under heavy IO load can stall longer than 300 seconds. 2) IBM reported elevated lock contention in their testbed (likely due to increased back pressure due to IO not being dispatched as quickly): https://www.redhat.com/archives/dm-devel/2015-July/msg00057.html Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 2caf492..e8d8456 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1053,13 +1053,10 @@ static struct dm_rq_target_io *tio_from_request(struct request *rq) */ static void rq_completed(struct mapped_device *md, int rw, bool run_queue) { - int nr_requests_pending; - atomic_dec(&md->pending[rw]); /* nudge anyone waiting on suspend queue */ - nr_requests_pending = md_in_flight(md); - if (!nr_requests_pending) + if (!md_in_flight(md)) wake_up(&md->wait); /* @@ -1071,8 +1068,7 @@ static void rq_completed(struct mapped_device *md, int rw, bool run_queue) if (run_queue) { if (md->queue->mq_ops) blk_mq_run_hw_queues(md->queue, true); - else if (!nr_requests_pending || - (nr_requests_pending >= md->queue->nr_congestion_on)) + else blk_run_queue_async(md->queue); } -- 2.7.4