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    SubjectRe: [patch] lockless, scalable get_pid(), for_each_process() elimination, 2.5.35-BK

    On Wed, 18 Sep 2002, Rik van Riel wrote:
    > On second thought ... yes there's a reason. Suppose you have
    > 100000 threads on your box already, how long is it going to
    > take to walk them all to figure out the pid distribution ?
    > And are you willing to walk 100000 threads for every 16 pids allocated ?

    Give me a real-life case where that happens, and I might care. I dare you.

    The pid space is not a uniform distribution, which your made-up-example
    depends on. So you usually walk the 100000 threads _once_, and then you
    don't have to walk them again for quite a long time.

    And guys, if this is a performance problem for some extreme site, the fix
    is truly trivial:

    echo $((0x7fffffff)) > /proc/sys/max_pid

    and you're done.

    You're completely making up a problem that is not a problem in real life.
    Come back to me when the above doesn't work _in_practice_ and somebody is
    actually bitten, and maybe I'll care.

    Until then, all you're doing is mental masturbation.


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