cfq-iosched: improve hw_tag detection (1a1238a7) · Commits · 戴 / test

If active queue hasn't enough requests and idle window opens, cfq will not dispatch sufficient requests to hardware. In such situation, current code will zero hw_tag. But this is because cfq doesn't dispatch enough requests instead of hardware queue doesn't work. Don't zero hw_tag in such case. Signed-off-by:

Shaohua Li <shaohua.li@intel.com> Signed-off-by:

Jens Axboe <jens.axboe@oracle.com>

block/cfq-iosched.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -2257,6 +2257,8 @@ static void cfq_insert_request(struct request_queue q, struct request rq)
		*/
		static void cfq_update_hw_tag(struct cfq_data *cfqd)
		{
		struct cfq_queue *cfqq = cfqd->active_queue;

		if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
		cfqd->rq_in_driver_peak = rq_in_driver(cfqd);

		@@ -2264,6 +2266,16 @@ static void cfq_update_hw_tag(struct cfq_data *cfqd)
		rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
		return;

		/*
		* If active queue hasn't enough requests and can idle, cfq might not
		* dispatch sufficient requests to hardware. Don't zero hw_tag in this
		* case
		*/
		if (cfqq && cfq_cfqq_idle_window(cfqq) &&
		cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
		CFQ_HW_QUEUE_MIN && rq_in_driver(cfqd) < CFQ_HW_QUEUE_MIN)
		return;

		if (cfqd->hw_tag_samples++ < 50)
		return;

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