From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [virtio-dev] Zerocopy VM-to-VM networking using virtio-net Date: Fri, 24 Apr 2015 10:20:28 +0200 Message-ID: <5539FCCC.60708@redhat.com> References: <20150422170138.GA8388@stefanha-thinkpad.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Luke Gorrie , Stefan Hajnoczi Cc: Andrew Jones , "Michael S. Tsirkin" , Rik van Riel , virtualization@lists.linux-foundation.org, virtio-comment@lists.oasis-open.org, "Dr. David Alan Gilbert" List-Id: virtualization@lists.linuxfoundation.org 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