Re: [Qemu-devel] [snabb-devel] Re: [PATCH v6 1/2] vhost-user: add multi queue support

[Yuanhan Liu]

On Mon, Aug 31, 2015 at 02:30:06PM +0300, Michael S. Tsirkin wrote:
[snip..] 
> > Then how about the other case:
> > When startup the vhost backend, user specify 8 queues, like:
> > Vhost-user ...  -queues 8      # Y=8
> > When startup the guest, user specify 4 queues, like:
> > Qemu-kvm ... -queues 4      # X=4
> > 
> > Vhost backend CAN support the queues number as much as the guest/qemu 
> > requires,
> > And qemu don't want enable all of them(8 in the case), just part of 
> > them(only 4 from 8).
> > Will qemu exit or go forward(of course with 4 queues)? 
> 
> I think it must go forward since guest does not have to
> configure all queues anyway - and that's built in to virtio spec.
> 
> Note that # of queues in actual use in fact changes dynamically
> too, without restaring the device.

May I know how do you do that? I mean, is there a public interface, like
by some commands? Or, by sending vhost messages?

        --yliu