Open Stack

> -----Original Message-----
> From: Henry Gessau [mailto:gessau at cisco.com]
> Sent: Tuesday, October 29, 2013 2:23 PM
> To: OpenStack Development Mailing List (not for usage questions)
> Subject: Re: [openstack-dev] [nova] [neutron] PCI pass-through network
> support
> 
> On Tue, Oct 29, at 4:31 pm, Jiang, Yunhong <yunhong.jiang at intel.com>
> wrote:
> 
> > Henry,why do you think the "service VM" need the entire PF instead of a
> > VF? I think the SR-IOV NIC should provide QoS and performance
> isolation.
> 
> I was speculating. I just thought it might be a good idea to leave open the
> possibility of assigning a PF to a VM if the need arises.
> 
> Neutron service VMs are a new thing. I will be following the discussions
> and
> there is a summit session for them. It remains to be seen if there is any
> desire/need for full PF ownership of NICs. But if a service VM owns the PF
> and has the right NIC driver it could do some advanced features with it.
> 
At least in current PCI implementation, if a device has no SR-IOV enabled, then that device will be exposed and can be assigned (is this your so-called PF?). If a device has SR-IOV enabled, then only VF be exposed and the PF is hidden from resource tracker. The reason is, when SR-IOV enabled, the PF is mostly used to configure and management the VFs, and it will be security issue to expose the PF to a guest.

I'm not sure if you are talking about the PF, are you talking about the PF w/ or w/o SR-IOV enabled. 

I totally agree that assign a PCI NIC to service VM have a lot of benefit from both performance and isolation point of view.

Thanks
--jyh