How do you assign the number of cores via an ssh script?

Hello,

i have a batch script file that is run on an ssh with the following format:

nohup matlab -nodesktop -nosplash -nodisplay <script_file.m>& output_script_file.txt &

I want to set the number of cores for the job to 6, seeing as the script_file.m uses a parfor loop. I know feature('numcores') will display the number of cores available, but I want to specifically assign the number of cores. Is this done through the batch script file, and if so how? If not, how can I assign the number of cores to a job on an ssh?

Thanks.

Answer 1

[Alessandro Maria Laspina]

I've tried running Walter Roberson's answer, but for some reason i've had to include maxNumCompThreads(6) in the script file at the start.

Also the > gave me an error as well.

This seemed to work:

nohup matlab -nodesktop -nosplash -nodisplay -batch <script_file> & output_script_file.txt &

EDIT:

As Walter Roberson wrote, > and & should not have a space, so it is:

nohup matlab -nodesktop -nosplash -nodisplay <script_file.m>& output_file.txt &

[Walter Roberson]

If I recall correctly, you are not permitted to have a space between the > and the &

[Alessandro Maria Laspina]

Indeed! Thank you for pointing it out.

Answer 2

[Walter Roberson]

https://www.mathworks.com/help/matlab/ref/maxnumcompthreads.html

However you could also consider modifying the cluster profile to limit the cores in it.

[Alessandro Maria Laspina]

Instead of maxnumcompthreads, wouldn't it be parpool(N) where N is the number of cores I force the script to use?

[Walter Roberson]

maxnumcompthreads also controls the number of cores permitted when MATLAB automatically parallelizes mathematical functions by calling MKL or LAPACK .

[Alessandro Maria Laspina]

So how would I set to the maximum number of cores to 6? And what are these MKL and LAPACK functions?

Is it like this?

nohup matlab -nodesktop -nosplash -nodisplay <script_file.m>& output_script_file.txt & maxNumCompThreads(6)

[Walter Roberson]

https://en.m.wikipedia.org/wiki/LAPACK

[Walter Roberson]

nohup matlab -batch 'maxNumCompThreads(6);script_file' &> output_script_file.txt &

[Alessandro Maria Laspina]

Had to change the syntax a bit for it to work. Thanks for the help!

[Raymond Norris]

Also consider using the -logfile switch

nohup matlab -batch 'maxNumCompThreads(6);script_file' -logfile output_script_file.txt &