[Openstack-operators] pci passthrough & numa affinity

Jonathan D. Proulx jon at csail.mit.edu
Fri May 25 01:58:35 UTC 2018

On Thu, May 24, 2018 at 06:34:06PM -0500, Eric Fried wrote:
:How long are you willing to wait?
:The work we're doing to use Placement from Nova ought to allow us to
:model both of these things nicely from the virt driver, and request them
:nicely from the flavor.
:By the end of Rocky we will have laid a large percentage of the
:groundwork to enable this. This is all part of the road to what we've
:been calling "generic device management" (GDM) -- which we hope will
:eventually let us remove most/all of the existing PCI passthrough code.
:I/we would be interested in hearing more specifics of your requirements
:around this, as it will help inform the GDM roadmap.  And of course,
:upstream help & contributions would be very welcome.

Sounds like good work.

My use case is not yet very clear.  I do have some upcoming
discussions with users around requirements and funding so being able
to say "this is on the road map and could be accelerated with
developer hours"  is useful.  I expect patience is what will come of
that but very good to know where to go when I get some clarity and if
I get some resources.


:On 05/24/2018 05:19 PM, Jonathan D. Proulx wrote:
:> On Fri, May 25, 2018 at 07:59:16AM +1000, Blair Bethwaite wrote:
:> :Hi Jon,
:> :
:> :Following up to the question you asked during the HPC on OpenStack
:> :panel at the summit yesterday...
:> :
:> :You might have already seen Daniel Berrange's blog on this topic:
:> :https://www.berrange.com/posts/2017/02/16/setting-up-a-nested-kvm-guest-for-developing-testing-pci-device-assignment-with-numa/
:> :? He essentially describes how you can get around the issue of the
:> :naive flat pci bus topology in the guest - exposing numa affinity of
:> :the PCIe root ports requires newish qemu and libvirt.
:> Thanks for the pointer not sure if I've seen that one, I've seen a few
:> ways to map manually.  I would have been quite surprised if nova did
:> this so I am poking at libvirt.xml outside nova for now
:> :However, best I can tell there is no way to do this with Nova today.
:> :Are you interested in working together on a spec for this?
:> I'm not yet convinced it's worth the bother, that's the crux of the
:> question I'm investigating.  Is this worth the effort?  There's a meta
:> question "do I have time to find out" :)
:> :The other related feature of interest here (newer though - no libvirt
:> :support yet I think) is gpu cliques
:> :(https://github.com/qemu/qemu/commit/dfbee78db8fdf7bc8c151c3d29504bb47438480b),
:> :would be really nice to have a way to set these up through Nova once
:> :libvirt supports it.
:> Thanks,
:> -Jon
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