On Thu, May 30, 2013 at 08:40:47AM -0500, Anthony Liguori wrote: > Stefan Hajnoczi <stefanha@xxxxxxxxx> writes: > > > On Thu, May 30, 2013 at 7:23 AM, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote: > >> Anthony Liguori <anthony@xxxxxxxxxxxxx> writes: > >>> Rusty Russell <rusty@xxxxxxxxxxxxxxx> writes: > >>>> On Fri, May 24, 2013 at 08:47:58AM -0500, Anthony Liguori wrote: > >>>>> FWIW, I think what's more interesting is using vhost-net as a networking > >>>>> backend with virtio-net in QEMU being what's guest facing. > >>>>> > >>>>> In theory, this gives you the best of both worlds: QEMU acts as a first > >>>>> line of defense against a malicious guest while still getting the > >>>>> performance advantages of vhost-net (zero-copy). > >>>>> > >>>> It would be an interesting idea if we didn't already have the vhost > >>>> model where we don't need the userspace bounce. > >>> > >>> The model is very interesting for QEMU because then we can use vhost as > >>> a backend for other types of network adapters (like vmxnet3 or even > >>> e1000). > >>> > >>> It also helps for things like fault tolerance where we need to be able > >>> to control packet flow within QEMU. > >> > >> (CC's reduced, context added, Dmitry Fleytman added for vmxnet3 thoughts). > >> > >> Then I'm really confused as to what this would look like. A zero copy > >> sendmsg? We should be able to implement that today. > >> > >> On the receive side, what can we do better than readv? If we need to > >> return to userspace to tell the guest that we've got a new packet, we > >> don't win on latency. We might reduce syscall overhead with a > >> multi-dimensional readv to read multiple packets at once? > > > > Sounds like recvmmsg(2). > > Could we map this to mergable rx buffers though? > > Regards, > > Anthony Liguori Yes because we don't have to complete buffers in order. > > > > Stefan -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
