linux-kernel - Re: [regression 2.6.39-rc2][bisected] "perf, x86: P4 PMU - Read proper MSR register to catch" and NMIs

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Message-ID: <20110407001658.GW12642@redhat.com>
Date:	Wed, 6 Apr 2011 20:16:58 -0400
From:	Don Zickus <dzickus@...hat.com>
To:	Shaun Ruffell <sruffell@...ium.com>
Cc:	linux-kernel@...r.kernel.org,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [regression 2.6.39-rc2][bisected] "perf, x86: P4 PMU - Read
 proper MSR register to catch" and NMIs

On Wed, Apr 06, 2011 at 05:30:36PM -0500, Shaun Ruffell wrote:
> Hello Don,
> 
> I was able to bisect it down to commit 242214f9c1eeaae40, but I'm not
> certain where to go from here.  Is this something that is already known
> or is there more information I should try to collect? 

Nope, this is an ongoing issue.  What happened was the perf P4 nmi handler
was swallowing all the NMIs.  My patch fixed that and exposed a double NMI
problem.  We have been chasing it for a couple of months.  I think Cyril
was finally able to duplicate it (as he wrote the P4 code).  I have
confidence that he will find a fix for it soon. :-)

Thanks for the report though!

Cheers,
Don
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