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Re: [Xen-devel] [Hackathon minutes] PV frontends/backends and NUMA machines

On mar, 2013-05-21 at 11:28 +0100, George Dunlap wrote:
> On 05/21/2013 11:24 AM, Tim Deegan wrote:
> > At 10:45 +0100 on 21 May (1369133137), George Dunlap wrote:
> >> What we would want for a comparable domU -- a domU that was NUMA-aware
> >> -- was to have the pfn layout in batches across the nodes to which it
> >> will be pinned.  E.g., if a domU has its NUMA affinity set to nodes 2-3,
> >> then you'd want the first half of the pfns to come from node 2, the
> >> second half from node 3.
> >>
> >> In both cases, the domain builder will need to call the allocator with
> >> specific numa nodes for specific regions of the PFN space.
> >
> > Ah, so that logic lives in the tools for domU?  I was misremembering.
> > Anyway, I think I'm convinced that this is a reasonable thing to do
> > the dom0 building code. :)
> I don't think it lives anywhere at the moment -- 
Yep, the issue is there is no such logic at all yet! :-P

> I think at the moment 
> the domain builder for both dom0 and domU just call the allocator 
> without any directions, and the allocator reads the NUMA affinity mask 
> for the domain.
And stripes the allocation through such mask, yes, without caring at all
where specific regions end up... Actually, without knowing anything
about 'specific regions'.

>   But yes, when we do get guest NUMA support, I think the 
> domain builder will be the right place to set up the guest NUMA layout, 
> both for domUs and dom0.

> Matt Wilson I think has some patches to do the domU layout for HVM 
> guests -- if he could post those at some point in the next month, it 
> might give a head start to the person implementing this (probably me at 
> this point).
Yes, that would surely help. In the meantime, I replied to your first
e-mail in this thread with the links to all the old patches I've been
able to find on this subject... Hope that helps too. :-)


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