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    SubjectRe: [PATCH] mm: call cond_resched() per MAX_ORDER_NR_PAGES pages copy
    On 11/18/2013 01:56 PM, Naoya Horiguchi wrote:
    >> > Why bother trying to "optimize" it?
    > I thought that if we call cond_resched() too often, the copying thread can
    > take too long in a heavy load system, because the copying thread always
    > yields the CPU in every loop.

    I think you're confusing cond_resched() and yield(). The way I look at it:

    yield() means: "Hey scheduler, go right now and run something else I'm
    done running"

    cond_resched() means: "Schedule me off if the scheduler has already
    decided something else _should_ be running"

    I'm sure I'm missing some of the subtleties, but as I see it, yield()
    actively goes off and finds something else to run. cond_resched() only
    schedules you off if you've *already* run too long.




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