linux-kernel - RE: [PATCH V5 1/2] perf ignore LBR and extra

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Message-ID: <37D7C6CF3E00A74B8858931C1DB2F077014E1B03@SHSMSX103.ccr.corp.intel.com>
Date:	Mon, 14 Jul 2014 13:44:32 +0000
From:	"Liang, Kan" <kan.liang@...el.com>
To:	Paolo Bonzini <pbonzini@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
CC:	"andi@...stfloor.org" <andi@...stfloor.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: RE: [PATCH V5 1/2] perf ignore LBR and extra_regs



> -----Original Message-----
> From: Paolo Bonzini [mailto:pbonzini@...hat.com]
> Sent: Monday, July 14, 2014 9:40 AM
> To: Liang, Kan; Peter Zijlstra
> Cc: andi@...stfloor.org; linux-kernel@...r.kernel.org; kvm@...r.kernel.org
> Subject: Re: [PATCH V5 1/2] perf ignore LBR and extra_regs
> 
> Il 14/07/2014 15:36, Liang, Kan ha scritto:
> >> > Kan Liang, what happens if CONFIG_PARAVIRT=y?  Do you get garbage
> >> > or just no events reported?
> >> >
> > Guest rdmsr/wrmsr will eventually call rdmsr_safe/wrmsr_safe. They will
> handle the #GP. So there is no error report in guest.
> 
> Yeah, but what's the effect on the output of perf?

They can be still counted/sampled, but the results are garbage.

Kan

> 
> Paolo

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