On Monday 10 August 2009, Stephen Hemminger wrote: > On Mon, 10 Aug 2009 16:32:01, "Fischer, Anna" <anna.fischer@xxxxxx> wrote: > > How would this work though, if the OS inside the guest wants to register > > to a particular multicast address? Is this propagated through the backend > > drivers to the macvlan/macvtap interface? > > Sure filtering is better, but multicast performance with large number > of guests is really a corner case, not the real performance issue. Well, right now, qemu does not care at all about this, it essentially leaves the tun device in ALLMULTI state. I should check whether macvtap at this stage can receive multicast frames at all, but if it does, it will get them all ;-). If we want to implement this with kvm, we would have to start with the qemu virtio-net implementation, to move the receive filter into the tap device. With tun/tap that will mean less copying to user space, with macvtap (after implementing TUNSETTXFILTER) we get already pretty far because we no longer need to have the external interface in ALLMULTI state. Once that is in place, we can start thinking about filtering per virtual device. Arnd <>< _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
