[CentOS-virt] XEN and RH 6
pasik at iki.fi
Tue Nov 10 22:27:17 UTC 2009
On Tue, Nov 10, 2009 at 11:36:39PM +0200, Pasi Kärkkäinen wrote:
> On Tue, Nov 10, 2009 at 01:52:36PM -0500, Scott McClanahan wrote:
> > > Yeah.. Xen paravirtualized mmu is fast, and in some (many) cases beats
> > > CPU hardware virtualized mmu.
> > >
> > > KVM has 'pvmmu' aswell, but it's not as good, so KVM is faster with CPU
> > > hardware virtualization. But that's a problem of KVM only, they haven't
> > > managed to optimize the pvmmu. And they're going to drop it altogether.
> > >
> > > KVM people tend to say 'paravirtualized mmu is slow', but they just mean
> > > KVM implementation of it sucks :)
> > >
> > > -- Pasi
> > I haven't tested or seen any benchmarks but I wonder how much the
> > addition of a page table for virtualized guests will help. Not to
> > mention newer features like a virtualized task priority register and
> > ASID could continue to require less paravirt code in the guest. I get
> > my two new 5500 series servers in a few weeks so I'm pretty excited to
> > see some of the second gen hardware virtualization assist features in
> > action.
> I don't know. Of course hardware will add features and get more
> optimized in the future.
> Some benchmarks from IBM guys, Xen vs. KVM:
And forgot this one:
> "So, KVM requires 66.93/52.85 = 26.6% more CPU to do the same amount of work."
> "If we normalize to CPU utilization, Xen is doing 20% more throughput."
> "KVM running Windows VMs uses 46% more CPU than the Other-Hypervisor"
> "A different hypervisor was compared; KVM used about 60% more CPU cycles to complete the same amount of work."
> I bet KVM will catch up at some point.. at the moment it seems to not
> perform as good as Xen. Then again it's a much younger product.
More information about the CentOS-virt