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    SubjectRe: [PATCH, RFC 0/6] Avoid cache trashing on clearing huge/gigantic page
    On Mon, Jul 23, 2012 at 04:30:20PM -0700, Andrew Morton wrote:
    > On Fri, 20 Jul 2012 15:50:16 +0300
    > "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> wrote:
    >
    > > Clearing a 2MB huge page will typically blow away several levels of CPU
    > > caches. To avoid this only cache clear the 4K area around the fault
    > > address and use a cache avoiding clears for the rest of the 2MB area.
    > >
    > > It would be nice to test the patchset with more workloads. Especially if
    > > you see performance regression with THP.
    > >
    > > Any feedback is appreciated.
    >
    > This all looks pretty sane to me. Some detail-poking from the x86 guys
    > would be nice.
    >
    > What do other architectures need to do? Simply implement
    > clear_page_nocache()?

    And define ARCH_HAS_USER_NOCACHE to 1.

    > I believe that powerpc is one, not sure about
    > others. Please update the changelogs to let arch maintainers know
    > what they should do and cc those people on future versions?

    Okay.

    --
    Kirill A. Shutemov
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