Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug()
From: Jens Axboe
Date: Fri Sep 18 2015 - 10:24:01 EST
On 09/18/2015 07:16 AM, Chris Mason wrote:
On Thu, Sep 17, 2015 at 11:04:03PM -0700, Linus Torvalds wrote:
On Thu, Sep 17, 2015 at 10:40 PM, Dave Chinner <david@xxxxxxxxxxxxx> wrote:
Ok, makes sense - the plug is not being flushed as we switch away,
but Chris' patch makes it do that.
Yup.
Huh, that does make much more sense, thanks Linus. I'm wondering where
else I've assumed that cond_resched() unplugged.
And I actually think Chris' patch is better than the one I sent out
(but maybe the scheduler people should take a look at the behavior of
cond_resched()), I just wanted you to test that to verify the
behavior.
It makes no sense for preemption schedule to NOT unplug, the fact that
it doesn't is news to me as well. It was never the intent of the
unplug-on-schedule to NOT unplug for certain schedule out events, that
seems like very odd behavior.
--
Jens Axboe
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