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    SubjectRe: [PATCH] mm: do not drain pagevecs for mlock
    >> Because your test program is too artificial. 20sec/100000times =
    >> 200usec. And your
    >> program repeat mlock and munlock the exact same address. so, yes, if
    >> lru_add_drain_all() is removed, it become near no-op. but it's
    >> worthless comparision.
    >> none of any practical program does such strange mlock usage.
    > yes, I should say it is artificial. But mlock did cause the problem in
    > our product system and perf shows that the mlock uses the system time
    > much more than others. That's the reason we created this program to test
    > whether mlock really sucks. And we compared the result with
    > rhel5(2.6.18) which runs much much faster.
    >
    > And from the commit log you described, we can remove lru_add_drain_all
    > safely here, so why add it? At least removing it makes mlock much faster
    > compared to the vanilla kernel.

    If we remove it, we lose to a test way of mlock. "Memlocked" field of
    /proc/meminfo
    show inaccurate number very easily. So, if 200usec is no avoidable,
    I'll ack you.
    But I'm not convinced yet.


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