Re: [libvirt] Qemu/KVM is 3x slower under libvirt (due to vhost=on)

On 09/28/11 11:53, Daniel P. Berrange wrote: >On Wed, Sep 28, 2011 at 11:49:01AM +0200, Reeted wrote: >>YES! >>It's the vhost. With vhost=on it takes about 12 seconds more time to boot. >> >>...meaning? :-) >I've no idea. I was always under the impression that 'vhost=on' was >the 'make it go much faster' switch. So something is going wrong >here that I cna't explain. > >Perhaps one of the network people on this list can explain... > > >To turn vhost off in the libvirt XML, you should be able to use ><driver name='qemu'/> for the interface in question,eg > > > <interface type='user'> > <mac address='52:54:00:e5:48:58'/> > <model type='virtio'/> > <driver name='qemu'/> > </interface> Ok that seems to work: it removes the vhost part in the virsh launch hence cutting down 12secs of boot time. If nobody comes out with an explanation of why, I will open another thread on the kvm list for this. I would probably need to test disk performance on vhost=on to see if it degrades or it's for another reason that boot time is increased.