Re: Performance monitoring units and KVM II

Andi Kleen
2008-01-31T03:44:55Z

> Sure it could, but that would be a new interface. If you were
> free to define a new interface you could also just go completely
> hypercall based.

Actually thinking about it more it would be probably possible for
KVM to emulate ArchPerfMon on AMD and Family 15 Intel based on
the local PMU. ArchPerfmon has only a few defined counters which
can likely be all emulated with other counters.

Then the migration would work and PMU also.

The only issue is that some clients might check the cpu vendor/model/family
in addition to the ArchPerfMon. So to do successfull migration you
would always need to fake an ArchPerfMon capable CPU in CPUID initially.
So e.g. even if you ran on AMD SVM you would need to fake a Yonah or Core2.o

Not sure if that had other bide side effects. Perhaps it could be made
optional.

-Andi