On Mon, 31 Jul 2023 08:46:51 -0700, Jakub Kicinski <kuba@xxxxxxxxxx> wrote: > On Mon, 31 Jul 2023 09:23:29 +0800 Jason Wang wrote: > > > I'd step back and ask you why do you want to use AF_XDP with virtio. > > > Instead of bifurcating one virtio instance into different queues why > > > not create a separate virtio instance? > > > > I'm not sure I get this, but do you mean a separate virtio device that > > owns AF_XDP queues only? If I understand it correctly, bifurcating is > > one of the key advantages of AF_XDP. What's more, current virtio > > doesn't support being split at queue (pair) level. And it may still > > suffer from the yes/no DMA API issue. > > I guess we should step even further back and ask Xuan what the use case > is, because I'm not very sure. All we hear is "enable AF_XDP on virtio" > but AF_XDP is barely used on real HW, so why? Why just for real HW? I want to enable AF_XDP on virtio-net. Then the user can send/recv packets by AF_XDP bypass through the kernel. That has be used on large scale. I donot know what is the problem of the virtio-net. Why do you think that the virtio-net cannot work with AF_XDP? > > Bifurcating makes (used to make?) some sense in case of real HW when you > had only one PCI function and had to subdivide it. Sorry I do not get this. > Virtio is either a SW > construct or offloaded to very capable HW, so either way cost of > creating an extra instance for DPDK or whatever else is very low. The extra instance is virtio-net? I think there is a gap. So let me give you a brief introduction of our case. Firstly, we donot use dpdk. We use the AF_XDP, because of that the AF_XDP is more simpler and easy to deploy for the nginx. We use the AF_XDP to speedup the UDP of the quic. By the library, the APP just needs some simple change. On the AliYun, the net driver is virtio-net. So we want the virtio-net support the AF_XDP. I guess what you mean is that we can speed up through the cooperation of devices and drivers, but our machines are public clouds, and we cannot change the back-end devices of virtio under normal circumstances. Here I do not know the different of the real hw and the virtio-net. Thanks.
