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    SubjectRe: Overscheduling DOES happen with high web server load.
    On Fri, 7 May 1999, Greg Lindahl wrote:

    >Why is schedule called so frequently? The thundering herd. You get a
    >new connection, everyone wakes up, only one gets work, and everyone
    ^^^^^^^^^^^^^^^^^^ wrong
    >else goes back to sleep, each causing O(A) work to reschedule. M hits

    The reality until 2.2.7 is that everyone wakes up, need_resched of the
    current task is set to 1 so the rescheduled CPU will issue a schedule()
    very shortly, but nobody of the wakenup tasks gets rescheduled and
    schedule() become a nono. This is the main wastage of resources. I think
    it's just fixed in pre-2.2.8-4 though ;).

    Andrea Arcangeli


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