From b9d8f4c73b1af4cfd53f819bf84c2bce31232275 Mon Sep 17 00:00:00 2001 From: Gui Jianfeng Date: Tue, 8 Dec 2009 08:54:17 +0100 Subject: [PATCH] cfq: Optimization for close cooperating queue searching It doesn't make any sense to try to find out a close cooperating queue if current cfqq is the only one in the group. Signed-off-by: Gui Jianfeng Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 5009af4..b19cd68 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1750,6 +1750,12 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, return NULL; /* + * Don't search priority tree if it's the only queue in the group. + */ + if (cur_cfqq->cfqg->nr_cfqq == 1) + return NULL; + + /* * We should notice if some of the queues are cooperating, eg * working closely on the same area of the disk. In that case, * we can group them together and don't waste time idling. -- 1.8.2.3