Re: [ovirt-users] feedback and questions about SR-IOV feature

Le 06/12/2016 à 13:19, Martin Polednik a écrit : > On 06/12/16 12:14 +0100, Nathanaël Blanchet wrote: > >> Hello, >> >> My new 10G NICS support now SR-IOV, and I've played with this new >> feature as passthrough device, so as to reduce my host CPU consumption. >> >> At the origin, I set up a bond on both 10G PF nics. >> >> After many configurations, the only way I manage to use a VF into a VM, >> is to get out of the bond one nic. >> >> So does it mean that it is impossible to run a VM with VF with PF >> attached to a bond? >> > > As far as I know, it's not possible to do that. The reason is that the > bond normally creates new (logical) interface, what you are doing is > assigning "part" of the bond directly to a VM and the driver within VM > isn't aware of the bond. > This is what I supposed, UI should prevent us to create VFfrom when nic is attached to a bond. Pencil icon should'nt appear in this case. > > Moreover, something strange happens : during the boot of the VM, the >> passthrough device gets an dhcp IP on the native vlan of the bond, and once >> finally up, the real vlan used by this device is on the different >> predifined vlan. It implies to me to reconfigure the network to ping >> something on the wanted vlan. Really crazy. >> > > This could be explained by previous statement: bonding PFs at > hypervisor level and then assigning VFs to a VM can most likely cause > undefined behavior. > The issue is the same when the PF is not attached to a bond, so in an expected working situation. > > Other question is : In which case can it be useful to be able to bond 2 >> VF? UI let us to do so, but it is impossible to add any bridge on that >> virtual bond. >> > > At hypervisor level? I believe it doesn't make sense. > I wonder this because UI allows to do it. The same as above, user shouldn't be allowed to bond two VFs, and not allowed to add virtual network to a VF > If you require bond between 2 PFs, you can assign 2 VFs each from > different PF to a VM and bond them within the guest. > > Comparing to a large number of restrictions (migration and others), my >> opinion is that this feature seems to be very difficult to use in >> production... >> > > The use case for SR-IOV is maximum performance at the cost of > convenience while still (somewhat) allowing you to scale. > > -- >> Nathanaël Blanchet >> >> Supervision réseau >> Pôle Infrastrutures Informatiques >> 227 avenue Professeur-Jean-Louis-Viala >> 34193 MONTPELLIER CEDEX 5 >> Tél. 33 (0)4 67 54 84 55 >> Fax 33 (0)4 67 54 84 14 >> blanchet(a)abes.fr >> >> > _______________________________________________ >> Users mailing list >> Users(a)ovirt.org >> http://lists.ovirt.org/mailman/listinfo/users >> > > -- Nathanaël Blanchet Supervision réseau Pôle Infrastrutures Informatiques 227 avenue Professeur-Jean-Louis-Viala 34193 MONTPELLIER CEDEX 5 Tél. 33 (0)4 67 54 84 55 Fax 33 (0)4 67 54 84 14 blanchet(a)abes.fr _______________________________________________ Users mailing list Users(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/users