luck/tmp_suning_uos_patched
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block: don't flush plugged IO on forced preemtion scheduling

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We really only want to unplug the pending IO when the process actually
goes to sleep.  So move the test for flushing the plug up to the place
where we actually deactivate the task - where we have properly checked
for preemption and for the process really sleeping.

Acked-by: Jens Axboe <jaxboe@fusionio.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2011-04-13 08:08:20 -07:00
parent a626ca6a65
commit 6631e635c6
1 changed files with 10 additions and 10 deletions
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20
kernel/sched.c
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@ -4111,20 +4111,20 @@ asmlinkage void __sched schedule(void)
try_to_wake_up_local(to_wakeup);
}
deactivate_task(rq, prev, DEQUEUE_SLEEP);
/*
* If we are going to sleep and we have plugged IO queued, make
* sure to submit it to avoid deadlocks.
*/
if (blk_needs_flush_plug(prev)) {
raw_spin_unlock(&rq->lock);
blk_flush_plug(prev);
raw_spin_lock(&rq->lock);
}
}
switch_count = &prev->nvcsw;
}
/*
* If we are going to sleep and we have plugged IO queued, make
* sure to submit it to avoid deadlocks.
*/
if (prev->state != TASK_RUNNING && blk_needs_flush_plug(prev)) {
raw_spin_unlock(&rq->lock);
blk_flush_plug(prev);
raw_spin_lock(&rq->lock);
}
pre_schedule(rq, prev);
if (unlikely(!rq->nr_running))