Re: [virtio-dev] Zerocopy VM-to-VM networking using virtio-net

[Paolo Bonzini <pbonzini@redhat.com>]

On 24/04/2015 10:12, Luke Gorrie wrote:
> 
>     I think this approach could be fruitful in bringing virtio-net to
>     VM-to-VM networking use cases.  Unless virtio-net is extended for this
>     use case, I'm afraid DPDK and OpenDataPlane communities might steer
>     clear of VIRTIO.
> 
> 
> Questions:
> 
> - How fast is needed?
> 
> - How fast is the vhost-user support that shipped in DPDK 2.0?

vhost-user is fast.  The problem is not the speed, it's the desire of a
more peer-to-peer operation.

virtio by design has very distinct roles for driver and device, so for
VM2VM communication the virtio design requires two devices in the guest
and two drivers, comprising a "switch", in the host.

The switch could be using vhost-user indeed, but my understanding is
that in some cases this switch component is undesirable.  However, my
understanding does not include _why_ it is undesirable.  This is where
we need to gather more information from the DPDK folks.

Paolo