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 <>
Signed-off-by: default avatarJens Axboe <>
parent a6151c3a
...@@ -1093,6 +1093,15 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd) ...@@ -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))
cfq_mark_cfqq_wait_request(cfqq); cfq_mark_cfqq_wait_request(cfqq);
/* /*
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