OpenMp set number of threads for parallel loop depending on variable

Question

Is there a way to set number of threads in OpenMP parallel for region based on the value of a variable? Initially for the whole application number of threads = nofCores. On my AMD FX 8350, nofCores =8. For this area if the variable is 3 then I only need 3 threads. If variable>cores then number of threads should remain equal to nofCores.

I do not want to set the number of threads globally for all the application. Just for this specific parallel loop.

Sorry if this is a naive question, but I am a newbie in OpenMP.

make sure to look into the documentation; it's not that massive. — Sebastian Mach
– Sebastian Mach, Commented Oct 8, 2013 at 14:23

CPlus · Accepted Answer · 2023-04-14 01:28:04Z

33

Add this to your omp parallel for directive:

#pragma omp parallel for num_threads(variable)
for( ... )

edited Apr 14, 2023 at 1:28

CPlus

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answered Oct 8, 2013 at 12:52

eduffy

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