[CentOS-virt] XEN and RH 6

Tue Nov 10 15:10:25 UTC 2009
Dennis J. <dennisml at conversis.de>

On 11/10/2009 03:57 PM, Grant McWilliams wrote:
>     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?
>     Regards,
>        Dennis
>     __________
> 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..

I get that but if the line is becoming this blurry (with KVM apparently 
beeing "somewhat" paravirtualized) does it make sense anymore to 
distinguish between HVM/PV?