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    SubjectRe: [PATCH] MM: implement MADV_FREE lazy freeing of anonymous memory
    Nick Piggin wrote:

    > OK, sure. I think we need more numbers though.

    Thinking about the issue some more, I think I know just the
    number we might want to know.

    It is pretty obvious that the kernel needs to do less work
    with the MADV_FREE code present. However, it is possible
    that userspace needs to do more work, by accessing pages
    that are not in the CPU cache, or in another CPU's cache.

    In the test cases where you see similar performance on the
    workload with and without the MADV_FREE code, are you by any
    chance seeing lower system time and higher user time?

    I think that maybe for 2.6.22 we should just alias MADV_FREE
    to run with the MADV_DONTNEED functionality, so that the glibc
    people can make the change on their side while we figure out
    what will be the best thing to do on the kernel side.

    I'll send in a patch that does that once Linus has committed
    your most recent flood of patches. What do you think?

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