Open Stack

Hi Chris,

I note two of your comments --

> > When we worked on H release, we target for basic PCI support like
> > accelerator card or encryption card etc.

PU> So I note that you are already solving the PCI pass through usecase somehow ? How ? If you have solved this already in terms of architecture then SRIOV should not be difficult.

> Do we run into the same complexity if we have spare physical NICs on
> the host that get passed in to the guest?

PU> In part you are correct. However there is one additional thing. When we have multiple physical NIC's, the Compute Node's linux is still in control over those. So the data into the VM and out still travels all those tunneling devices and finally goes out of these physical NIC's. The NIC is _not_ exposed directly to the VM. The VM still has the emulated NIC which interfaces out with the tap and over the linux bridge....
In case of SRIOV, you can dice up a single physical NIC into multiple NIC's (effectively), and expose each of these diced up NIC's to a VM each. This means that the VM will now 'directly' access the NIC bypassing the Hypervisor. Similar to PCI pass through, but now you have one pass through for each VM with the diced NIC.  So that is a major consideration to keep in mind because this means that we will bypass all those tunneling devices in the middle. But since you say that you are working with PCI passthrough and seem to have solved it, this is a mere extension of that.

Further, for single physical NIC which is diced up and is connected to VM's on a single Compute Node, the NIC provides a 'switch' using which these VM's can talk to each other. This can aid us because we have bypassed all the tunneling devices.
But if there are two physical NIC's which were diced up with SRIOV, then VM's on the diced parts of the first  physical NIC cannot communicate easily with the VM's on the diced parts of the second physical NIC.
So a native implementation has to be there on the Compute Node which will aid this (this native implementation will take over the Physical Function, PF of each NIC) and will be able to 'switch' the packets between VM's of different physical diced up NIC's [if we need that usecase]

Regards
-Prashant


-----Original Message-----
From: Irena Berezovsky [mailto:irenab at mellanox.com]
Sent: Thursday, October 10, 2013 12:15 PM
To: Jiang, Yunhong; Chris Friesen; openstack at lists.openstack.org
Cc: OpenStack Development Mailing List (openstack-dev at lists.openstack.org)
Subject: Re: [openstack-dev] [Openstack] Neutron support for passthrough of networking devices?

Hi Chris, Jiang,
We are also looking into enchantment of basic PCI pass-through to provide SR-IOV based networking.
In order to support automatic provisioning, it requires the awareness to what virtual network to connect the requested SR-IOV device.
This should be considered by the scheduler  in order to run VM on the Host that is connected to the physical network.
It requires the Neutron to be aware of PCI pass though allocated device and allocate port on the virtual network.
It will require some sort of VIF Driver to manage the libvirt device settings.
It may also require neutron agent to apply port policy on the device. I think it makes sense to  support this as part of ML2 neutron plugin (via mechanism driver).
In case you plan to attend the design summit, maybe it worth to collaborate there and discuss what can be done in the coming  Icehouse release?

Regards,
Irena

-----Original Message-----
From: Jiang, Yunhong [mailto:yunhong.jiang at intel.com]
Sent: Thursday, October 10, 2013 2:26 AM
To: Chris Friesen; openstack at lists.openstack.org
Subject: Re: [Openstack] Neutron support for passthrough of networking devices?

Several thing in my mind:
a) NIC need more information like the switch, and these information need be managed by nova also. We have basic support, but not fully implemented.
b) How to setup the device, including the mac address or 802.1Qbh etc. Libvirt have several option to support it, need more work to support them, also need consider other virt driver like xenapi etc.
c) How to achieve the isolation of tenants, and how to setup like the router in Neutron. I'm not well on Neutron, but I think others may have more idea on it.

Thanks
--jyh

> -----Original Message-----
> From: Chris Friesen [mailto:chris.friesen at windriver.com]
> Sent: Wednesday, October 09, 2013 11:53 AM
> To: openstack at lists.openstack.org
> Subject: Re: [Openstack] Neutron support for passthrough of networking
> devices?
>
> On 10/09/2013 12:31 PM, Jiang, Yunhong wrote:
> > When we worked on H release, we target for basic PCI support like
> > accelerator card or encryption card etc. I think SR-IOV network
> > support is more complex and requires more effort, in both Nova side
> > and Neutron side. We are working on some enhancement in Nova side
> > now. But the whole picture may need more time/discussion.
>
> Can you elaborate on the complexities?  Assuming you enable SR-IOV on
> the host, and pass it through to the guest using the normal PCI
> passthrough mechanisms, what's the extra complexity?
>
> Do we run into the same complexity if we have spare physical NICs on
> the host that get passed in to the guest?
>
> Thanks,
> Chris
>
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