cfq-iosched: tweak kick logic a bit more (2d870722) · Commits · 戴 / test

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 <jens.axboe@oracle.com>

block/cfq-iosched.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -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);
		}

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