Re: [PATCH 05/10] block: remove per-queue plugging
From: Peter Zijlstra <peterz@infradead.org>
Date: 2011-04-13 11:09:35
Also in:
dm-devel, lkml
On Tue, 2011-04-12 at 19:23 -0700, Linus Torvalds wrote:
quoted hunk ↗ jump to hunk
kernel/sched.c | 20 ++++++++++---------- 1 files changed, 10 insertions(+), 10 deletions(-)diff --git a/kernel/sched.c b/kernel/sched.c index 48013633d792..a187c3fe027b 100644 --- a/kernel/sched.c +++ b/kernel/sched.c@@ -4111,20 +4111,20 @@ need_resched: 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))
Right, that cures the preemption problem. The reason I suggested placing it where it was is that I'd like to keep all things that release rq->lock in the middle of schedule() in one place, but I guess we can cure that with some extra comments.