[torqueusers] MATLAB and cpusets

[Christopher Samuel]

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On 15/12/10 21:22, Martin Thompson wrote:

> If a MATLAB job requests a subset of the available cores
> on a compute node, say 6 out of 12, then it will use those
? 6 cores if it is the only job running on that node.
> However, if another job was already running on that node,
> say using the other 6 cores, then MATLAB will not use its
> full allocation of cores.

Hmm, I've actually seen the opposite issue where MATLAB
will attempt to use all the detected cores on a system
irrespective of the cpuset it is in.  Which if the user
has requested just a single core (as they thought it was
only going to use 1) makes things go rather badly for
them with 8 threads fighting over the 1 allocated core.

I suggested to the user that they set OMP_NUM_THREADS
to be 1 before running this code and that seemed to
fix it though I'm still trying to find out from them
if it improved the running of their code.

cheers,
Chris
- -- 
 Christopher Samuel - Senior Systems Administrator
 VLSCI - Victorian Life Sciences Computational Initiative
 Email: samuel at unimelb.edu.au Phone: +61 (0)3 903 55545
         http://www.vlsci.unimelb.edu.au/

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