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    SubjectRe: [patch] scheduler cache affinity improvement for 2.4 kernels
    On Tue, 13 Nov 2001, Mike Kravetz wrote:

    > On Thu, Nov 08, 2001 at 03:30:11PM +0100, Ingo Molnar wrote:
    > >
    > > i've attached a patch that fixes a long-time performance problem in the
    > > Linux scheduler.
    >
    > Just got back from holiday and saw this patch. I like the idea
    > slowing down task dynamic priority modifications (the counter
    > field). My only thought/concern would be in the case where a
    > task with maximum dynamic priority (counter value) decides to
    > use 'all' of its timeslice. In such a case, the task can not
    > be preempted by another task (with the same static priority)
    > until its entire timeslice is expired. In the current scheduler,
    > I believe the task can be preempted after 1 timer tick. In
    > practice, this shouldn't be an issue. However, it is something
    > we may want to think about. One simple solution would be to
    > update a tasks dynamic priority (counter value) more frequently
    > it it is above its NICE_TO_TICKS value.

    Mike, take a look at my next post in this thread.
    I'm using a watermark value of 10 :


    if (p->counter > TICKS_WMARK)
    --p->counter;
    else if (++p->timer_ticks >= p->counter) {
    p->counter = 0;
    p->timer_ticks = 0;
    p->need_resched = 1;
    }





    - Davide


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