[libvirt-users] VM Performance using KVM Vs. VMware ESXi

[Daniel P. Berrange]

On Tue, Apr 14, 2015 at 04:53:52PM +0530, Jatin Davey wrote:
> On 4/14/2015 4:42 PM, Dominique Ramaekers wrote:
> >
> >About Spice: I think it’s good practice to use spice because it improves
> >the performance of the VM in general by improving screen performance. If
> >your VM is constantly displaying output, you’ll probably will notice a
> >difference.
> >
> [Jatin] Ok, This is not my concern as of now. I will take a look at it
> sometime later.
> >
> >About virtio: You can see it in the settings. Better yet, it’s in your
> >XML. If you post your XML, we can take a look…
> >
> 
> Here is the xml associated with my VM:
> 
> ********************************
> <domain type='kvm'>

>   <devices>
>     <emulator>/usr/libexec/qemu-kvm</emulator>
>     <disk type='file' device='disk'>
>       <driver name='qemu' type='qcow2' cache='none'/>
>       <source file='/var/lib/libvirt/images/****.qcow2'/>
>       <target dev='hda' bus='ide'/>
>       <address type='drive' controller='0' bus='0' target='0' unit='0'/>
>     </disk>

This disk is configured to use IDE, so performance of anything that does
disk I/O is going to be terrible. You really want to be using virtio.

>    <interface type='bridge'>
>      <mac address='52:54:00:c9:58:c9'/>
>      <source bridge='br332'/>
>      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
>     </interface>

This doesn't have any model listed at all, so it will be falling back to
a generic emulated NIC. Again performance of this is likely going to be
terrible for anything doing network I/O. You want to be using virtio for
this too.

Regards,
Daniel
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