Re: [libvirt-users] <qemu:commandline> domain XML tag is not working?
On Tue, Apr 21, 2015 at 09:54:57AM +0800, Chengyuan Li wrote:
Hi Kashyap,
Here I want to test and see how much I/O performance could be improved
by virtio-blk data plane feature. Yes, this is a dirty way to enable
it :-),
You mentioned using newer libvirt, is there parameter similar
"x-data-plane=on" in new version libvirt?
Sorry, I didn't mean there's a specific version with this attribute
turned 'on'. In fact, from my 'grep'ing in the source tree, it is not
the case. I merely mentioned it as there have been numerous fixes in
various areas over the year and if you're in a test environment, it's
preferabl to use the newest versions.
--
/kashyap
On Mon, Apr 20, 2015 at 10:51 PM, Kashyap Chamarthy
<kchamart(a)redhat.com>
wrote:
> On Mon, Apr 20, 2015 at 10:37:13PM +0800, Chengyuan Li wrote:
> > Hi,
> >
> > I tried to enable virtio-blk data plane feature for VMs in my openstack
> > environment, the hypervisor is ubuntu 14.04, libvirt 1.2.2
>
> [I haven't tested the virtio-blk data plane myself.]
>
> This libvirt version seems a little old (from March 2014), you might
> want to move to a bit newer.
>
> > and QEMU 2.0.
> > As nova doesn't support that parameter yet, I did belows
> >
> > 1. nova boot a VM with raw disk image.
> > 2. nova stop the VM.
> > 3. run "virsh edit <instance-id>" on the hyprvisor node, and
adding below
> > into instance xml just before </domain>.
>
> You're modifying the guest definition behind Nova's back, so you get to
> keep all the pieces if something breaks. :-)
>
> > However, the <qemu:commandline> part is ignored and not saved after
> closing
> > virsh edit, seems that libvirt rejected these changes. Is there any XML
> > syntax error here? Or libvirt doesn't support <qemu:commandline>
tag?
> >
> > <qemu:commandline>
> > <qemu:arg value='-set'/>
> > <qemu:arg
value='device.drive-virtio-disk0.x-data-plane=on'/>
> > </qemu:commandline>
>