linux-kernel - Re: [PATCH -tip] perf, x86: Make a second write to performance counter if needed

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Date:	Tue, 08 Jun 2010 17:18:39 +0800
From:	Lin Ming <ming.m.lin@...el.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Cyrill Gorcunov <gorcunov@...nvz.org>, Ingo Molnar <mingo@...e.hu>,
	Robert Richter <robert.richter@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Frédéric Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH -tip] perf, x86: Make a second write to performance
 counter if needed

On Mon, 2010-06-07 at 17:48 +0800, Peter Zijlstra wrote:
> On Thu, 2010-06-03 at 01:23 +0400, Cyrill Gorcunov wrote:
> > On Netburst PMU we need a second write to a performance counter
> > due to cpu erratum.
> > 
> > A simple flag test instead of alternative instructions was choosen
> > because wrmsrl is already a macro and if virtualization is turned
> > on will need an additional wrapper call which is more expencise.
> > 
> > nb: we should propably switch to jump-labels as only this facility
> > reach the mainline.
> 
> OK. Thanks Cyrill.


I tested this patch and it works well for pre-defined events.

Lin Ming

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