From aeb6fafb8fa53266d70ca7474fcda2bdaf96524a Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 6 Apr 2009 14:48:07 +0200 Subject: block: Add flag for telling the IO schedulers NOT to anticipate more IO By default, CFQ will anticipate more IO from a given io context if the previously completed IO was sync. This used to be fine, since the only sync IO was reads and O_DIRECT writes. But with more "normal" sync writes being used now, we don't want to anticipate for those. Add a bio/request flag that informs the IO scheduler that this is a sync request that we should not idle for. Introduce WRITE_ODIRECT specifically for O_DIRECT writes, and make sure that the other sync writes set this flag. Signed-off-by: Jens Axboe Signed-off-by: Linus Torvalds --- block/blk-core.c | 2 ++ block/cfq-iosched.c | 4 +++- 2 files changed, 5 insertions(+), 1 deletion(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index c4198f083e5b..25572802dac2 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1128,6 +1128,8 @@ void init_request_from_bio(struct request *req, struct bio *bio) req->cmd_flags |= REQ_UNPLUG; if (bio_rw_meta(bio)) req->cmd_flags |= REQ_RW_META; + if (bio_noidle(bio)) + req->cmd_flags |= REQ_NOIDLE; req->errors = 0; req->hard_sector = req->sector = bio->bi_sector; diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 664ebfd092ec..9e809345f71a 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1992,8 +1992,10 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq) } if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) cfq_slice_expired(cfqd, 1); - else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list)) + else if (sync && !rq_noidle(rq) && + RB_EMPTY_ROOT(&cfqq->sort_list)) { cfq_arm_slice_timer(cfqd); + } } if (!cfqd->rq_in_driver) -- cgit v1.2.1