From 2d870722965211de072bb36b446a4df99dae07e1 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 15 Apr 2009 12:12:46 +0200 Subject: [PATCH] cfq-iosched: tweak kick logic a bit more We only kick the dispatch for an idling queue, if we think it's a (somewhat) fully merged request. Also allow a kick if we have other busy queues in the system, since we don't want to risk waiting for a potential merge in that case. It's better to get some work done and proceed. Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index e59f210..579f318 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1905,10 +1905,13 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, * of tiny requests, because we disrupt the normal plugging * and merging. If the request is already larger than a single * page, let it rip immediately. For that case we assume that - * merging is already done. + * merging is already done. Ditto for a busy system that + * has other work pending, don't risk delaying until the + * idle timer unplug to continue working. */ if (cfq_cfqq_wait_request(cfqq)) { - if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE) { + if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || + cfqd->busy_queues > 1) { del_timer(&cfqd->idle_slice_timer); blk_start_queueing(cfqd->queue); } -- 2.7.4