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Commit 355b659c authored by Corrado Zoccolo's avatar Corrado Zoccolo Committed by Jens Axboe
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cfq-iosched: avoid probable slice overrun when idling 



If the average think time is larger than the remaining time slice
for any given queue, don't allow it to idle. A succesful idle also
means that we need to dispatch and complete a request, so if we don't
even have time left for the idle process, we would overrun the slice
in any case.

Signed-off-by: default avatarCorrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent a6151c3a

block/cfq-iosched.c

+9 −0
Original line number Original line Diff line number Diff line
@@ -1093,6 +1093,15 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd) 
	if (!cic || !atomic_read(&cic->ioc->nr_tasks))

	if (!cic || !atomic_read(&cic->ioc->nr_tasks))

		return;

		return;





	/*

	 * If our average think time is larger than the remaining time

	 * slice, then don't idle. This avoids overrunning the allotted

	 * time slice.

	 */

	if (sample_valid(cic->ttime_samples) &&

	    (cfqq->slice_end - jiffies < cic->ttime_mean))

		return;



	cfq_mark_cfqq_wait_request(cfqq);

	cfq_mark_cfqq_wait_request(cfqq);





	/*

	/*