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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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