MATLAB: Using parfor

parallel computingParallel Computing Toolboxparfor

Hi I successfully implemented a parfor loop in Matlab. However on my computer which has 4 cores I am not getting the improvement in computation time I expected to get. When I go to the task manager and check the CPU usage it rarely goes over 25% which is the same as before the parfor loop What could be the problem?

Best Answer

What kind of problem have you set up using parfor.. a general fact about the Parallel Computing Toolbox is that the parallel tasks have to be pretty intensive/expensive in order for parallelization be effective..

If your computation is trivial then you might not get the speedup you expect.. Not a lot more can be said without looking at what code you have parallelized.

Also, is your machine quad core or a two core hyperthreaded which would show up as 4 virtual cores?

Related Solutions

MATLAB: MATLAB Distributed Computing Server

Yes, you can open a matlabpool using MDCS workers and run PARFOR and SPMD.

MATLAB: How to create pool of workers from a list of hostnames

This isn't feasible at this time; however, you might consider wrapping your code with batch. For example, let's assume your code looks something like this

function my_parallel_code
% ...
nworkers = ... ;
% Check if a parallel pool is running.  If so, use it.  If not, initiate a parallel pool with 'nworkers'
p = gcp('nocreate');
if isempty(p)
    % Pool has not been started, spawn pool across multiple nodes (kicks of new job)
    % If the pool has already been started, it would have been done in "submit_job" with call to batch()
    parpool('hpc',nworkers);    
end
parfor idx = 1:N
    % parallel code
end

Now, write a wrapper function

function submit_job
c = parcluster('hpc');
j = c.batch(@my_parallel_code,0,{},'Pool',nworkers);

Submit your MATLAB job (e.g. using Slurm). Call submit_job instead of my_parallel_code directly

#SBATCH -n 1
module load matlab
matlab -batch submit_job

Best Answer

Related Solutions

MATLAB: MATLAB Distributed Computing Server

MATLAB: How to create pool of workers from a list of hostnames

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