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Re: [OCLUG-Tech] How good is Linux at NUMA ?

On Fri, 2006-03-31 at 01:19 -0500, Adrian Irving-Beer wrote:
> On Thu, Mar 30, 2006 at 07:25:14PM -0500, Peter Sjoberg wrote:
> 
> > Just look at http://www.jroller.com/page/jaimec?entry=sparc_linux
> 
> I guess you stopped reading before the comments, where people debunk
> the entry, and then the original poster basically says, "oops, guess I
> was totally wrong" and closes the topic. :)
Yes, I confess that I stopped to early (read it after my post).

I still wonder how well NUMA is implemented but feel I need to read the
source and join the kernel mailing list to get more answers, and in the
end it's just because I'm interested, not because I need to know for
work or anything.

Does Linux Opteron implementation of NUMA
Try to allocate process memory on same cpu: YES!

Have some NumaAPI so a process can manage thread creation to some
degree: Yes

If no more memory is available on current cpu, does malloc grab from any
other cpu (2 level NUMA) or make a difference between far (1 jump) and
farther (2 jump) CPUs (multi level NUMA): ?no?
If Yes, limited to 3 levels or ?

If current CPU core is overloaded, does it recognize that the other core
is just as good from a memory standpoint and migrate the process?: ?

Migrate a process to another CPU when memory usage grows and current
node is full while another node has enough to have to hold the whole
process: ?no?

Have some kind of numa awareness when managing io (network, disk) for  a
process: ?? (or is it _always_ the user space process that creates every
buffer involved in io?)



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