Re: [PATCH v2 00/11] KVM in-guest performance monitoring

[Avi Kivity <avi@redhat.com>]

On 06/15/2011 03:40 PM, David Ahern wrote:
> On 06/15/2011 02:57 AM, Avi Kivity wrote:
> >  Okay.  If you do anything interesting with it, please let us know.  I
> >  only tested the watchdog, 'perf top', and 'perf stat'.
> >
>
> For the following I was using the userspace command from latest
> perf-core branch.
>
> cycles H/W event is not working for me, so perf-top did not do much
> other than start.

Strange, IIRC it did for me.  I'll re-test.

> perf-stat -ddd shows a whole lot of 0's - which is interesting. It means
> time enabled and time running are non-0, yet the counter value is 0.
> cycles and instructions events also show as not counted

Most of those counters aren't supported by the emulated PMU.  What does 
dmesg say about Perf?

> Also, the numbers for branches and branch-misses just seem wrong
> compared to the same command run in the host as well as running
> perf-stat in the host on the vcpu thread running openssl (with the vcpu
> pinned to a pcpu).

Could be due to the fact that the counter is running in host mode.  Will 
be fixed once the exclude_host/exclude_guest patch makes it in (and 
gains Intel support).

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