From 895e3c5c58a80bb9e4e05d9ac38b4f30e0f97d80 Mon Sep 17 00:00:00 2001 From: majianpeng Date: Tue, 31 Jul 2012 10:05:44 +1000 Subject: md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE. 'sync' writes set both REQ_SYNC and REQ_NOIDLE. O_DIRECT writes set REQ_SYNC but not REQ_NOIDLE. We currently assume that a REQ_SYNC request will not be followed by more requests and so set STRIPE_PREREAD_ACTIVE to expedite the request. This is appropriate for sync requests, but not for O_DIRECT requests. So make the setting of STRIPE_PREREAD_ACTIVE conditional on REQ_NOIDLE rather than REQ_SYNC. This is consistent with the documented meaning of REQ_NOIDLE: __REQ_NOIDLE, /* don't anticipate more IO after this one */ Signed-off-by: Jianpeng Ma Signed-off-by: NeilBrown --- drivers/md/raid5.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 29493982dbf..259f519814c 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -4135,7 +4135,7 @@ static void make_request(struct mddev *mddev, struct bio * bi) finish_wait(&conf->wait_for_overlap, &w); set_bit(STRIPE_HANDLE, &sh->state); clear_bit(STRIPE_DELAYED, &sh->state); - if ((bi->bi_rw & REQ_SYNC) && + if ((bi->bi_rw & REQ_NOIDLE) && !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) atomic_inc(&conf->preread_active_stripes); mddev_check_plugged(mddev); -- cgit v1.2.3