Re: [PATCH v1 0/5] KVM in-guest performance monitoring

From: Avi Kivity
Date: Thu May 12 2011 - 05:54:19 EST


On 05/12/2011 12:47 PM, Jan Kiszka wrote:
>
> Anyway, I thought about a paravirt-approach instead of implementing a
> real PMU... But there are certainly good reasons for both.

Paravirt is taking away the pressure from CPU vendors to do their virt
extensions properly - and doesn't help with unmodifiable OSes.

Yes. In the case of the PMU things are less clear, since they are very model specific. In the case of Linux, you have to lie to the guest and present a model number that it doesn't recognize, otherwise it prefers the model-specific PMU to the architectural PMU.

I though of adding a kvm cpuid bit that says "prefer the architectural pmu" to work around this issue.

--
error compiling committee.c: too many arguments to function

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