[libvirt-users] <qemu:commandline> domain XML tag is not working?

[Chengyuan Li]

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?
Please let know me you if you have better solution.



Regards,
CY.

On Mon, Apr 20, 2015 at 10:51 PM, Kashyap Chamarthy <kchamart at 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>
>
>
> --
> /kashyap
>
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