On 9/27/2018 5:23 AM, Sylvain Bauza wrote:
On Thu, Sep 27, 2018 at 2:46 AM Matt Riedemann <mriede...@gmail.com
<mailto:mriede...@gmail.com>> wrote:
On 9/26/2018 5:30 PM, Sylvain Bauza wrote:
> So, during this day, we also discussed about NUMA affinity and we
said
> that we could possibly use nested resource providers for NUMA
cells in
> Stein, but given we don't have yet a specific Placement API
query, NUMA
> affinity should still be using the NUMATopologyFilter.
> That said, when looking about how to use this filter for vGPUs,
it looks
> to me that I'd need to provide a new version for the NUMACell
object and
> modify the virt.hardware module. Are we also accepting this
(given it's
> a temporary question), or should we need to wait for the
Placement API
> support ?
>
> Folks, what are you thoughts ?
I'm pretty sure we've said several times already that modeling NUMA in
Placement is not something for which we're holding up the extraction.
It's not an extraction question. Just about knowing whether the Nova
folks would accept us to modify some o.vo object and module just for a
temporary time until Placement API has some new query parameter.
Whether Placement is extracted or not isn't really the problem, it's
more about the time it will take for this query parameter ("numbered
request groups to be in the same subtree") to be implemented in the
Placement API.
The real problem we have with vGPUs is that if we don't have NUMA
affinity, the performance would be around 10% less for vGPUs (if the
pGPU isn't on the same NUMA cell than the pCPU). Not sure large
operators would accept that :(
-Sylvain
I don't know how close we are to having whatever we need for modeling
NUMA in the placement API, but I'll go out on a limb and assume we're
not close. Given that, if we have to do something within nova for NUMA
affinity for vGPUs for the NUMATopologyFilter, then I'd be OK with that
since it's short term like you said (although our "short term"
workarounds tend to last for many releases). Anyone that cares about
NUMA today already has to enable the scheduler filter anyway.
--
Thanks,
Matt
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