From 83c38830b04d4e369b9a41acbc562c0422f2f2f2 Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Tue, 3 Nov 2009 02:22:06 +0100 Subject: [PATCH] drbd: performance - don't lose unplug events Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg --- drivers/block/drbd/drbd_req.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c index 3678d3d66c6c..d09aac4a84ec 100644 --- a/drivers/block/drbd/drbd_req.c +++ b/drivers/block/drbd/drbd_req.c @@ -505,7 +505,7 @@ void __req_mod(struct drbd_request *req, enum drbd_req_event what, * corresponding hlist_del is in _req_may_be_done() */ hlist_add_head(&req->colision, ar_hash_slot(mdev, req->sector)); - set_bit(UNPLUG_REMOTE, &mdev->flags); /* why? */ + set_bit(UNPLUG_REMOTE, &mdev->flags); D_ASSERT(req->rq_state & RQ_NET_PENDING); req->rq_state |= RQ_NET_QUEUED; @@ -536,6 +536,11 @@ void __req_mod(struct drbd_request *req, enum drbd_req_event what, * * Add req to the (now) current epoch (barrier). */ + /* otherwise we may lose an unplug, which may cause some remote + * io-scheduler timeout to expire, increasing maximum latency, + * hurting performance. */ + set_bit(UNPLUG_REMOTE, &mdev->flags); + /* see drbd_make_request_common, * just after it grabs the req_lock */ D_ASSERT(test_bit(CREATE_BARRIER, &mdev->flags) == 0); -- 2.30.2