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

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Date:	Thu, 20 Aug 2009 16:24:51 +1000
From:	Anton Blanchard <anton@...ba.org>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
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

 
Hi,

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

Sure:

http://ozlabs.org/~anton/junkcode/context_switch.c

Very simple, just run it once per core:

for i in `seq 0 31`
do
	taskset -c $i ./context_switch &
done

Then look at the context switch rates in vmstat.

Anton
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