Date: Thu, 12 May 2011 16:29:40 +0200
From: Joerg Roedel <joro@8bytes.org>
To: Avi Kivity <avi@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        Ingo Molnar <mingo@elte.hu>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
        Borislav Petkov <borislav.petkov@amd.com>
Subject: Re: [PATCH v1 0/5] KVM in-guest performance monitoring
Message-ID: <20110512142940.GJ8707@8bytes.org>
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On Thu, May 12, 2011 at 04:38:17PM +0300, Avi Kivity wrote:
> On 05/12/2011 04:06 PM, Joerg Roedel wrote:

>> AMD processors don't implement that cpuid leaf.
>
> Right.  But if an AMD processor were to implement that leaf, it would be  
> in a compatible manner, yes?

No official statement, but I guess this is the case. I have to check
back, though.

> A paravirt PMU also has to be implemented on top of perf_events.   
> Otherwise we can't share this resource.  So the only question is what  
> the interface looks like.  The arch pmu is non-optimized, but well  
> specified and somewhat supported in guests.  A paravirt pmu is not so  
> well specified at this point but can be faster (less exits).

I agree that getting the interface right is certainly the most difficult
and important task here.

	Joerg

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