Re: [PATCH 4/4] kvm: Implement PEBS virtualization

From: Paolo Bonzini
Date: Thu Jun 19 2014 - 10:40:51 EST


Il 02/06/2014 21:57, Andi Kleen ha scritto:
> It would be a bigger concern if we expected virtual PMU migration to
> work, but I think it would be nice to update kvm_pmu_cpuid_update() to
> notice the presence/absence of the new CPUID bits, and then store that
> into per-VM kvm_pmu->pebs_allowed rather than relying only on the
> per-host perf_pebs_virtualization().

I hope at some point it can work. There shouldn't be any problems
with migrating to the same CPU model, in many cases (same event
and same PEBS format) it'll likely even work between models or
gracefully degrade.

The code is there in both kernel and QEMU, it's just very little tested.

Paolo
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