Re: VM Migration on a NUMA server?

[Dario Faggioli <dario.faggioli@citrix.com>]

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On Sat, 2015-08-01 at 06:21 +0000, Kun Cheng wrote:
> I've looked into those settings and vcpu affinities on Xen wiki page.
> However what I'm trying to argue about is memory should be migrated
> when vcpus are moved to another node. 
>
I still struggle a bit to understand what you mean. It's exactly what I
said (or, at least, what I tried to do) that memory is *not* moved right
now.

There's no mean to do that, and putting one together is something really
difficult. There probably would be benefits of having it in place, but
only if it's implemented in the proper way, and applied with the proper
policing, which all should be thought, discussed and implemented.

> But setting a vcpu's affinity only seems to allow vcpu migration
> between different nodes. As my NUMA server is on the way I cannot
> verify that. 
>
Well, that is correct, memory is not moved. The local migration trick,
which I described in my previous email, actually works "only" because
migrating a guest basically means re-creating it from scratch (although,
of course, the "new" guest resumes from where the "old" was when
migration started), and hence re-allocate all it's memory, rather than
moving it.

> Anyhow, moving memory really draws my interest now. 
>
Glad to hear that. Feel free to give it a try, and report here what you
find out. :-)

Regards,
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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