On Thu, Dec 17, 2009 at 07:28:00AM -0600, Anthony Liguori wrote: > Daniel P. Berrange wrote: > >>The more interesting invocation of vhost-net though is one where the > >>vhost-net device backs directly to a physical network card. In this > >>mode, vhost should get considerably better performance than the current > >>implementation. I don't know the syntax yet, but I think it's > >>reasonable to assume that it will look something like -net > >>tap,dev=eth0. The effect will be that eth0 is dedicated to the guest. > >> > > > >Ok, so in this model you have to create a dedicated ethXX device for > >every guest, no sharing ? > > > > Yup. You may be sharing a physical network device via SR-IOV, but from > libvirt's perspective, we're dedicating a physical device to a guest > virtual nic. > > >>I think there are a few ways libvirt could support vhost-net in this > >>second mode. The simplest would be to introduce a new tag similar to > >><source network='br0'>. In fact, if you probed the device type for the > >>network parameter, you could probably do something like <source > >>network='eth0'> and have it Just Work. > >> > >>Another model would be to have libvirt see an SR-IOV adapter as a > >>network pool whereas it handled all of the VF management. Considering > >>how inflexible SR-IOV is today, I'm not sure whether this is the best > >>model. > >> > > > >Agreed, given the hardware limitations I don't see that it is worth the > >bother. > > > >This new mode is not really what we'd call 'bridging' in libvirt network > >XML format, so I think we'll want to define a new type of network config > >for it in libvirt. Perhaps > > > > <network type='physical'> > > <source dev='eth0'/> > > </network> Opps, when i write <network> here I actually mean <interface> > > > >Or type='passthru' > > > > That certainly simplifies the problem. > > I don't know whether SR-IOV requires additional setup though wrt > programming the VF's mac address. It may make sense for libvirt to at > least do that. Oh sure, that's easy enough - if there's no MAC in the XML we autogenerate one anyway, so we always have a mac for every interface & do whatever is needed with that. Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :| -- Libvir-list mailing list Libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list