Re: [PATCH] mm: /prom/pid/clear_refs: avoid split_huge_page()

From: Cyrill Gorcunov
Date: Wed May 21 2014 - 15:57:34 EST


On Wed, May 21, 2014 at 12:34:46PM -0700, Andrew Morton wrote:
> On Wed, 21 May 2014 22:04:22 +0300 "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> wrote:
>
> > Currently we split all THP pages on any clear_refs request. It's not
> > necessary. We can handle this on PMD level.
> >
> > One side effect is that soft dirty will potentially see more dirty
> > memory, since we will mark whole THP page dirty at once.
>
> This clashes pretty badly with
> http://ozlabs.org/~akpm/mmots/broken-out/clear_refs-redefine-callback-functions-for-page-table-walker.patch
>
> > Sanity checked with CRIU test suite. More testing is required.
>
> Will you be doing that testing or was this a request for Cyrill & co to
> help?

We've talking to Kirill how to test is and end up that criu is
the best candidate (though I think I'll write selftest for
vanilla too, hopefully tomorrow).
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