Re: [PATCH V3] perf & kvm: Enhance perf to collect KVM guest os statistics from host side

Avi Kivity
2010-04-15T10:44:15Z

On 04/15/2010 01:40 PM, Joerg Roedel wrote:
>
>> That means an NMI that happens outside guest code (for example, in the
>> mmu, or during the exit itself) would be counted as if in guest code.
>>
> Hmm, true. The same is true for an NMI that happens between VMSAVE and
> STGI but that window is smaller. Anyway, I think we don't need the
> busy-wait loop. The NMI should be executed at a well defined point and
> we set the cpu_var back to NULL after that point.
>

The point is not well defined. Considering there are already at least
two implementations svm, I don't want to rely on implementation details.

We could tune the position of the loop so that zero iterations are
executed on the implementations we know about.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.