[CentOS-virt] performance differences between kvm/xen

Grant McWilliams grantmasterflash at gmail.com
Wed Oct 27 11:00:09 EDT 2010

These are old tests now and not necessarily perfect, but they were Xen

> and KVM on the same kernel. KVM very early on and not necessarily in
> its best light. The Xen dom0/domU kernel was also not the best light
> for Xen. The point was to try to compare them on the same kernel. Xen
> and KVM on the same kernel has happened in the form of OpenSUSE's
> forward port of the Xen dom0 kernel with KVM that is already in
> mainline. The pv_ops kernel is not fully mainline, but is getting
> close. Some distros now have Xen dom0 kernels based on the pv_ops
> kernel, which could also run KVM.
> I wonder if using things like puppet, the phoronix test suite, etc.
> are a simpler way to go? I guess it all depends on how general a
> benchmarking tool is needed.
> Thanks,
> Todd

Todd, I think there's more than one way to look at this as well. As Xen
becomes more of a product and less of an installable package
it will probably have to be profiled as a product. Say benchmark XCP on
particular hardware and benchmark RHEL KVM on the same hardware and ESX as
It makes sense to benchmark a XEN kernel and a KVM kernel if we have that
flexibility but that's starting to shrink. Another test that I don't think
is THAT important anymore is tesing Xen with and without pvops kernels.
There were some rumors going around that the old 2.6.18 kernel was faster
than the new pvops. I was going to put together tests and never got to it.
Not that it makes any difference in the future because the old kernel is
fast going

What I'd like to have is a standardized test with a way of multiple people
uploading it and comparing results so we can run it on as many systems as
Data correlation could then be done on the data. Currently we have one test
over here and another over there and the tests never seem to be updated or
run again to verify results. Maybe none of it matters as the hypervisor
becomes inconsequential.

I'm going to look at the tests you've done as soon as time permits.

Grant McWilliams

Some people, when confronted with a problem, think "I know, I'll use
Now they have two problems.
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