Re: [RFC PATCH 2/3] mm: Drop use of test_and_set_skip in favor of just setting skip

Alexander Duyck
2020-08-14T14:24:40Z

On Fri, Aug 14, 2020 at 12:19 AM Alex Shi <alex.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org> wrote:
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>
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> 在 2020/8/13 下午12:02, Alexander Duyck 写道:
> >
> > Since we have dropped the late abort case we can drop the code that was
> > clearing the LRU flag and calling page_put since the abort case will now
> > not be holding a reference to a page.
> >
> > Signed-off-by: Alexander Duyck <alexander.h.duyck-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
>
> seems the case-lru-file-mmap-read case drop about 3% on this patch in a rough testing.
> on my 80 core machine.

I'm not sure how it could have that much impact on the performance
since the total effect would just be dropping what should be a
redundant test since we tested the skip bit before we took the LRU
bit, so we shouldn't need to test it again after.

I finally got my test setup working last night. I'll have to do some
testing in my environment and I can start trying to see what is going
on.

Thanks.

- Alex