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SubjectRE: [rfc patch] Re: sched: incorrect argument used in task_hot()
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Ingo Molnar wrote on Friday, November 17, 2006 11:21 AM
> * Mike Galbraith <efault@gmx.de> wrote:
>
> > One way to improve granularity, and eliminate the possibility of
> > p->last_run being > rq->timestamp_tast_tick, and thereby short
> > circuiting the evaluation of cache_hot_time, is to cache the last
> > return of sched_clock() at both tick and sched times, and use that
> > value as our reference instead of the absolute time of the tick. It
> > won't totally eliminate skew, but it moves the reference point closer
> > to the current time on the remote cpu.
> >
> > Looking for a good place to do this, I chose update_cpu_clock().
>
> looks good to me - thus we will update the timestamp not only in the
> timer tick, but also upon every context-switch (when we acquire
> sched_clock() value anyway). Lets try this in -mm?

Certainly gets my vote. For my particular workload environment, there
are enough schedule activity on the remote CPU and in theory it should
make time calculation a lot better than what it is now. I will run a
couple of experiment to verify.

Acked-by: Ken Chen <kenneth.w.chen@intel.com>

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