[CentOS-virt] performance differences between kvm/xen

Wed Oct 20 06:12:14 UTC 2010
Grant McWilliams <grantmasterflash at gmail.com>

> > If I understand that paper correctly, HVM+VT-d outperforms PV by quite a
> > lot (if you have VT-d support on your system).
> >
> Thanks for that link. Just to make my criticism of the initial claim more
> clear: I don't claim that HVM can never be faster than PV but that you need
> to understand when exactly this is the case. For example I'm not sure that
> x86_64 vs. x86 really enters into this but I can definitely see VT-d making
> an impact there.
> Regards,
>    Dennis
Even though this is Intel talking I'd still be very sceptical of getting
those numbers since this is quite the opposite of what I've seen.
Maybe the vt-d is getting good enough to actually accelerate IO operations
but even so that would only happen on the latest hardware.

I will say that Xen has a really long packet path though.

Grant McWilliams
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