[Gllug] HugePages

[John Hearns]

On 29 October 2010 13:45, Kostas Georgiou <k.georgiou at atreides.org.uk> wrote:
> Remember that you are in a NUMA machine, you have 12Gb/3Gb available/free
> memory after your hugepages but it doesn't mean that all nodes have
> memory left. Your ls could be running in a memory starved node and you
> can guess the rest. I'll be interested to see what numactl --hardware
> gives after boot and later on.
>
> Here is an interesting article for the effects of NUMA in mysql
> http://jcole.us/blog/archives/2010/09/28/mysql-swap-insanity-and-the-numa-architecture/
>

Thanks Kostas for a good article.

But "The new architecture for multiple processors, starting with AMD’s
Opteron and Intel’s Nehalem2 processors
 (we’ll call these “modern PC CPUs”), is a Non-Uniform Memory Access
(NUMA) architecture,"

That's a bit of a surprise to people who have been building and
managing NUMA machines for donkey's years....


To look at the topology of your system, NUMA and otherwise, the hwloc
package makes some pretty pictures:
http://www.open-mpi.org/projects/hwloc/
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