[Beowulf] Again about NUMA (numactl and taskset)

[Håkon Bugge]

At 18:34 25.06.2008, Mikhail Kuzminsky wrote:
>Let me assume now the following situation. I 
>have OpenMP-parallelized application which have 
>the number of processes equal to number of CPU 
>cores per server. And let me assume that this 
>application uses not too more virtual memory, so 
>all the real memory used may be placed in RAM of *one* node.
>It's not the abstract question - a lot of 
>Gaussian-03 jobs we have fit to this situation, 
>and all the 8 cores for dual socket quad core 
>Opteron server will be "well loaded".
>
>Is it right that all the application memory (w/o 
>using of numactl) will be allocated (by Linux kernel) in *one* node ?

Guess the answer is, it depends. The memory will 
be allocated on the node where the thread first 
touching it is running. But you could use numastat to investigate the issue.


Håkon