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Use both multi core CPUs

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David on 4 Mar 2015
Answered: Edric Ellis on 5 Mar 2015
I have a two CPU multi core machine (16 cores each). I want to use a parfor loop on all 32 cores. But maxNumCompThreads gives me 16. In preferences I changed the maximum number of workers to 32, but when I open a parallel pool it still has only 16 workers. What do I need to configure to make use of all cores? If it matters my parfor loop is a perfect parallelisable task, i.e. no communication between iterations is needed.
Thanks for your help!

Accepted Answer

Edric Ellis
Edric Ellis on 5 Mar 2015
You need to edit the 'local' parallel profile to set the maximum number of workers to 32. See the doc. Once you've done that, you should be able to issue the following command:
parpool('local', 32)
and launch 32 workers.
Note that if MATLAB by default does not consider hyper-threaded cores, as these tend not to perform well for numerically intensive computations. So, you might well find that running 32 workers is actually slower than running 16, depending on the precise nature of your computation.

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