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| author | Mike Snitzer <snitzer@redhat.com> | 2015-02-24 11:03:22 -0500 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2015-02-24 17:44:47 -0500 |
| commit | 9068f2f15d5fc7a5c9dc6e6963913216ede0c745 (patch) | |
| tree | bf3e127510adc5d46c180e85267ce9042c4df232 | |
| parent | 41e546935a2f8a2a6797bd108b712b1314ea20a2 (diff) | |
| download | linux-dm-9068f2f15d5fc7a5c9dc6e6963913216ede0c745.tar.gz | |
dm: only run the queue on completion if congested or no requests pending
Notice: this object is not reachable from any branch.
On really fast storage it can be beneficial to delay running the
request_queue to allow the elevator more opportunity to merge requests.
Otherwise, it has been observed that requests are being sent to
q->request_fn much quicker than is ideal on IOPS-bound backends.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Notice: this object is not reachable from any branch.
| -rw-r--r-- | drivers/md/dm.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index fc928994028a5..6ffed8004b27c 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1021,10 +1021,13 @@ static void end_clone_bio(struct bio *clone, int error) */ 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 */ - if (!md_in_flight(md)) + nr_requests_pending = md_in_flight(md); + if (!nr_requests_pending) wake_up(&md->wait); /* @@ -1033,8 +1036,11 @@ static void rq_completed(struct mapped_device *md, int rw, bool run_queue) * back into ->request_fn() could deadlock attempting to grab the * queue lock again. */ - if (run_queue) - blk_run_queue_async(md->queue); + if (run_queue) { + if (!nr_requests_pending || + (nr_requests_pending >= md->queue->nr_congestion_on)) + blk_run_queue_async(md->queue); + } /* * dm_put() must be at the end of this function. See the comment above |