[lkml]   [2006]   [Nov]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRE: [rfc patch] Re: sched: incorrect argument used in task_hot()
Ingo Molnar wrote on Friday, November 17, 2006 11:21 AM
> * Mike Galbraith <> 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 <>

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2006-11-17 20:45    [W:0.086 / U:2.220 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site