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). 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
