Re: [RFC PATCH 0/4] Implement multiqueue virtio-net

Krishna Kumar2
2010-09-08T16:47:18Z

> On Wednesday 08 September 2010, Krishna Kumar2 wrote:
> > > The new guest and qemu code work with old vhost-net, just with
reduced
> > > performance, yes?
> >
> > Yes, I have tested new guest/qemu with old vhost but using
> > #numtxqs=1 (or not passing any arguments at all to qemu to
> > enable MQ). Giving numtxqs > 1 fails with ENOBUFS in vhost,
> > since vhost_net_set_backend in the unmodified vhost checks
> > for boundary overflow.
> >
> > I have also tested running an unmodified guest with new
> > vhost/qemu, but qemu should not specify numtxqs>1.
>
> Can you live migrate a new guest from new-qemu/new-kernel
> to old-qemu/old-kernel, new-qemu/old-kernel and old-qemu/new-kernel?
> If not, do we need to support all those cases?

I have not tried this, though I added some minimal code in
virtio_net_load and virtio_net_save. I don't know what needs
to be done exactly at this time. I forgot to put this in the
"Next steps" list of things to do.

Thanks,

- KK