Re: KVM Processor cache size

Andre Przywara
2010-08-02T22:43:54Z

Ricardo Martins wrote:
> Thanks for the answers...
>
> I am creating an environment with multiple virtual servers, my main
> concern is whether I have a noticeable
> loss of performance because of this problem, if the answer is yes I
> will find another solution for my host server.
For server workloads it is less of a concern, that's why this issue
hasn't been addressed for such a long time. Usually server workloads are
not restricted by cache size or cache access patterns, so you will not
notice a slowdown. Please note that QEMU does not restrict the actual
cache size of the CPU (which will be fully available to the guest), but
only the size _reported_ to the guest.
If you are still in doubt, you could do benchmarks with the default CPU
model and with -cpu host (maybe even with my patch) to determine whether
there is a difference.

Regards,
Andre.

--
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 488-3567-12