On Wed, Dec 7, 2011 at 12:10 PM, Jason Wang <jasowang@xxxxxxxxxx> wrote: > On 12/07/2011 05:08 PM, Stefan Hajnoczi wrote: > [...] > >>> > Consider the complexity of the host nic each with their own steering >>> > features, this series make the first step with minimal effort to try >>> > to let >>> > guest driver and host tap/macvtap co-operate like what physical nic >>> > does. >>> > There may be other method, but performance numbers is also needed to >>> > give >>> > the answer. >> >> I agree that performance results for this need to be shown. >> >> My original point is really that it's not a good idea to take >> individual steps without a good big picture because this will change >> the virtio-net device specification. If this turns out to be a dead >> end then hosts will need to continue to support the interface forever >> (legacy guests could still try to use it). So please first explain >> what the full stack picture is going to look like and how you think it >> will lead to better performance. You don't need to have all the code >> or evidence, but just enough explanation so we see where this is all >> going. > > I think I mention too little in the cover message. > > There's no much changes with Krishna's series except the method that > choosing a rx virtqueue. Since original series use different hash methods in > host (rxhash) and guest (txhash), a different virtqueue were chose for a > flow which could lead packets of a flow to be handled by different vhost > thread and vcpu. This may damage the performance. > > This series tries to let one vhost thread to process the packets of a flow > and also let the packets to be sent directly to a vcpu local to the thread > process the data. This is done by letting guest tell the desired queue form > which it want to receive the pakcet of a dedicated flow. > > So passing the hash from host to guest is needed to get the same hash in the > two sides. Then a guest programmable hash to queue table were introduced and > guest co-operate with the host through accelerate RFS in guest. Thanks for the context, that helps me understand it a little better. 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
