Re: [PATCH v2 0/7] vNUMA introduction.

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

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Hi again, Elena,

And thanks for the good work! :-)

On mer, 2013-11-13 at 22:25 -0500, Elena Ufimtseva wrote:
> vNUMA introduction
>
> [...]
>
> This patchset can be pulled from https://git.gitorious.org/xenvnuma/xenvnuma.git
> Linux patchset https://git.gitorious.org/xenvnuma/linuxvnuma.git
> 
AhA! When replying to the Linux series, I said the linuxvnuma.git repo
seemed empty, but trying again now it's cloning something... I guess you
either fixed this or it was just me having/bad timing. :-)

> Examples of booting vNUMA enabled PV Linux guest on real NUMA machine:
> 
> 1. Automatic vNUMA placement on real NUMA machine:
> 
> VM config:
> 
> memory = 16384
> vcpus = 4
> name = "rcbig"
> vnodes = 4
> vnumamem = [10,10]
> vnuma_distance = [10, 30, 10, 30]
> vcpu_to_vnode = [0, 0, 1, 1]
>
> [..]
>
> Comments:
> None of the configuration options are correct so default values were used.
>
And (talking without having looked at the patches yet), you do print a
warning when this happens, right? :-)

> Notes:
> *   to enable vNUMA in linux kernel the corresponding patch set should be
>     applied;
> *   automatic numa balancing featurue seem to be fixed in linux kernel:
>     https://lkml.org/lkml/2013/7/31/647
> 
Mmm... I'm quite curious about this, since we talked extensively about
it in Edinburgh. Does this mean you're not having issues with the NUMA
hinting page fault any longer? Even without doing anything, either in
Xen or Linux?

So what was that? The URL above is just someone reporting a quite
general 'memory corruption issue', and nothing about what the cause was
and whether and how it has been fixed? But even more important, was that
it that was causing the problem you were seeing?

> TODO:
> *   This version limits vdistance config option to only two values - same node 
>     distance and other node distance; This prevents oopses on latest (3.13-rc1)
>     linux kernel with non-symmetric distance;
>
Ok, that's fine for now. We'll work on allowing the syntax we agreed
with IanJ during last round of review (and yes, with "We", I mean
"I" :-D).

> *   cpu siblings for Linux machine and xen cpu trap should be detected and 
>     warning should be given; Add cpuid check if set in VM config;
> *   benchmarking;
>
That's a big one! I think I'll have something ready at least for
facilitating it soon.

Thanks again and 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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