[CentOS-virt] XEN and RH 6
grantmasterflash at gmail.com
Tue Nov 10 14:57:08 UTC 2009
> I've been wondering about the definition of PV in the context of KVM/Xen.
> In the Linux on Linux case for Xen PV practically means that in the HVM
> case I have to access block devices using /dev/hda while in the PV case I
> can use the faster /dev/xvda. When using KVM which apparently only supports
> HVM I can still install a guest using the virtio drivers which seem to do
> the same as the paravirtualized devices on Xen.
> So what is the KVM+virtio case if not paravirtualization?
All of it except for that! Your VM isn't just a process accessing a disk.
With KVM they've attacked the most commond devices - network and disk and
offered paravirtualized devices. This doesn't concern me as the speed has
proven to be good although in mysqlbench Xen still leads by quite a bit. I'm
concerned about everything else. With 41 interactive VMs I worry about how
fast the hypervisor can switch focus, the cpu utilization of each etc..
Some people, when confronted with a problem, think "I know, I'll use
Now they have two problems.
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