linux-kernel - Re: [rfc patch] Re: sched: incorrect argument used in task

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Date:	Fri, 17 Nov 2006 20:20:52 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Mike Galbraith <efault@....de>
Cc:	"Chen, Kenneth W" <kenneth.w.chen@...el.com>,
	nickpiggin@...oo.com.au,
	"Siddha, Suresh B" <suresh.b.siddha@...el.com>,
	linux-kernel@...r.kernel.org, Andrew Morton <akpm@...l.org>
Subject: Re: [rfc patch] Re: sched: incorrect argument used in task_hot()


* Mike Galbraith <efault@....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?

Acked-by: Ingo Molnar <mingo@...e.hu>

	Ingo
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