Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug()

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug()
Date	2015-09-28 16:50 +0200
Message-ID	<qdHUB-2nN-7@gated-at.bofh.it> (permalink)
References	(5 earlier) <qa3K2-3Fh-21@gated-at.bofh.it> <qa4PM-5bi-33@gated-at.bofh.it> <qa5Vx-6Jf-59@gated-at.bofh.it> <qa6oy-7wu-29@gated-at.bofh.it> <qa6ye-7HP-33@gated-at.bofh.it>
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On Fri, Sep 18, 2015 at 09:12:38AM -0700, Linus Torvalds wrote:
> 
> So I disagree with your notion that it's a recursion flag. It is
> absolutely nothing of the sort.

OK, agreed. I had it classed under recursion in my head, clearly I
indexed it sloppily. In any case I have a patch that kills off
PREEMPT_ACTIVE entirely.

I just have to clean it up, benchmark, split and write changelogs. But
it should be forthcoming 'soon'. As is, it boots..

> It gets set by preemption - and,
> somewhat illogically, by cond_resched().

I suspect that was done to make cond_resched() (voluntary preemption)
more robust and only have a single preemption path/logic. But all that
was done well before I got involved.
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Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Peter Zijlstra <peterz@infradead.org> - 2015-09-28 16:50 +0200
  Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-28 18:10 +0200
    Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Ingo Molnar <mingo@kernel.org> - 2015-09-29 10:00 +0200

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