On Thursday 11 February 2010, Xin, Xiaohui wrote: > >This does a lot of things that I had planned for macvtap. It's > >great to hear that you have made this much progress. > > > >However, I'd hope that we could combine this with the macvtap driver, > >which would give us zero-copy transfer capability both with and > >without vhost, as well as (tx at least) when using multiple guests > >on a macvlan setup. > > You mean the zero-copy can work with macvtap driver without vhost. > May you give me some detailed info about your macvtap driver and the > relationship between vhost and macvtap to make me have a clear picture then? macvtap provides a user interface that is largely compatible with the tun/tap driver, and can be used in place of that from qemu. Vhost-net currently interfaces with tun/tap, but not yet with macvtap, which is easy enough to add and already on my list. The underlying code is macvlan, which is a driver that virtualizes network adapters in software, giving you multiple net_device instances for a real NIC, each of them with their own MAC address. In order to do zero-copy transmit with macvtap, the idea is to add a nonblocking version of the aio_write() function that works a lot like your transmit function. For receive, the hardware does not currently know which guest is supposed to get any frame coming in from the outside. Adding zero-copy receive requires interaction with the device driver and hardware capabilities to separate traffic by inbound MAC address into separate buffers per VM. > >I'm assuming that the idea is to allow VMDq adapters to simply > >show up as separate adapters and have the driver handle this > >in a hardware specific way. > > Does the VMDq driver do so now? I don't think anyone has published a VMDq capable driver so far. I was just assuming that you were working on one. Arnd -- 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
