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    SubjectRe: [PATCH 4/4] mm: numa: Slow PTE scan rate if migration failures occur
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    On Thu, Mar 19, 2015 at 9:13 PM, Dave Chinner <david@fromorbit.com> wrote:
    >
    > Testing now. It's a bit faster - three runs gave 7m35s, 7m20s and
    > 7m36s. IOWs's a bit better, but not significantly. page migrations
    > are pretty much unchanged, too:
    >
    > 558,632 migrate:mm_migrate_pages ( +- 6.38% )

    Ok. That was kind of the expected thing.

    I don't really know the NUMA fault rate limiting code, but one thing
    that strikes me is that if it tries to balance the NUMA faults against
    the *regular* faults, then maybe just the fact that we end up taking
    more COW faults after a NUMA fault then means that the NUMA rate
    limiting code now gets over-eager (because it sees all those extra
    non-numa faults).

    Mel, does that sound at all possible? I really have never looked at
    the magic automatic rate handling..

    Linus


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