linux-kernel - Re: [patch] Performance Counters for Linux, v3

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Date:	Fri, 12 Dec 2008 13:45:45 -0600
From:	"Chris Friesen" <cfriesen@...tel.com>
To:	eranian@...il.com
CC:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Vince Weaver <vince@...ter.net>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Eric Dumazet <dada1@...mosbay.com>,
	Robert Richter <robert.richter@....com>,
	Arjan van de Veen <arjan@...radead.org>,
	Peter Anvin <hpa@...or.com>, Paul Mackerras <paulus@...ba.org>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [patch] Performance Counters for Linux, v3

stephane eranian wrote:

> What happens in the following test case:
> 
>    - 2-way system (cpu0, cpu1)
> 
>    - on cpu0, two processes P1, P2, each self-monitoring and counting event E1.
>      Event E1 can only be measured on counter C1.
> 
>    - on cpu1, there is a cpu-wide session, monitoring event E1, thus using C1
> 
>    - the scheduler decides to migrate P1 onto CPU1. You now have a
> conflict on C1.
> 
> How is this managed?

Prevent the load balancer from moving P1 onto cpu1?

Chris
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