Maximum number of workers in a parallel loop (local cluster) with Matlab R2014a?

I have a Macbook Pro Intel Core I7; which is the maximum number of workers in a parallel loop (local cluster) with Matlab R2014a? These are the characteristics of my laptop

hw.physicalcpu: 4

hw.logicalcpu: 8

Answer 1

[Friedrich]

Hi,

the rule of thumb is to use one worker per pyhsical core. This is also stated here.

[MRC]

Hence I can only use 4 workers?

[Friedrich]

You can use more, but if you do its likely that it does not speed things up anymore because your system does not have any futher computational ressources.

Simply try it out. Run with 4 workers and do the same with 8 and see what happens.

[Greg]

Just wanted to add my modest experimental result

sz = 450;
A = rand(sz,sz,'single');
B = rand(sz,sz,'single');

tic;
   parfor k = 1:sz^2
       fft2(A.*B);
   end
toc;

6 workers - 159 sec.

12 workers - 118 sec.