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

[Dario Faggioli <raistlin@linux.it>]

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On mar, 2013-05-21 at 09:49 +0100, George Dunlap wrote:
> On Tue, May 21, 2013 at 9:47 AM, George Dunlap
> > There are two aspects of this.  First would be, if dom0.nvcpus <
> > host.npcpus, to place the vcpus reasonably on the various numa nodes.
> 
> And indeed, if dom0.nvcpus < host.nnodes, to try to minimize the
> distance from the vcpus to all nodes on the system.
> 
Yep, we definitely want that too. I have patches for the toolstack
counterpart of this (when speaking about DomUs), but I was using a
quadratic (in the number of nodes) algorithm, and we need to find
something better to scan and make decisions out of the distances matrix,
and that is especially true if we're in Xen rather than in libxl I
guess. :-P

Also, IONUMA machines can possibly introduce additional constraints: for
instance, you almost likely want a vCPU on all the nodes that have an IO
controller attached!

Dario

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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