linux-kernel - Re: [tip:sched/core] sched: cpuacct: Use bigger percpu counter batch values for stats counters

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Message-Id: <20090820151017.2ba95d6e.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Thu, 20 Aug 2009 15:10:17 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Anton Blanchard <anton@...ba.org>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>, balbir@...ux.vnet.ibm.com,
	Bharata B Rao <bharata@...ux.vnet.ibm.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Ingo Molnar <mingo@...e.hu>, mingo@...hat.com, hpa@...or.com,
	linux-kernel@...r.kernel.org, schwidefsky@...ibm.com,
	balajirrao@...il.com, dhaval@...ux.vnet.ibm.com,
	tglx@...utronix.de, akpm@...ux-foundation.org
Subject: Re: [tip:sched/core] sched: cpuacct: Use bigger percpu counter
 batch values for stats counters

On Thu, 20 Aug 2009 16:05:28 +1000
Anton Blanchard <anton@...ba.org> wrote:

> 
> Hi,
> 
> > Agreed, the first hunk is dangerous, on the second hunk, I'm not sure
> > about the INT_MAX thing, that's a 4s gap per cpu, that might be a tad
> > much.
> 
> Yeah I somehow missed the fact we read it every timer tick. I was hoping
> for an easy fix but I guess we just need to set a reasonable batch size
> at runtime.
> 

Could you share contex-switch-test program ?
I'd like to play with it to find out what I can do against percpu counter.

Thanks,
-Kame

> Anton
> 

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