OpenMP - Running parallel code inside parallel code

Question

I have a function compute() that has parallelized matrix multiplication inside of it using OpenMP

#pragma omp parallel for

This function is called many times in a loop - which I would like to run in parallel. Will there be any issues in running parallel code inside other parallel code?

This is c++ compiled on Ubuntu.

Mysticial · Accepted Answer · 2011-09-07 17:20:03Z

9

It will work fine, but you'll need to enable OpenMP nesting for it to work.

Call

omp_set_nested(1);

at the start of the program and it will allow you to have nested parallel regions.

However: Be aware, that you could end up running many more threads than what you want. So you will want to limit the # of threads of both the top and inner parallel regions.

answered Sep 7, 2011 at 17:20

Mysticial

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1 Comment

Mikhail Over a year ago

This is excellent. I forgot the word nested, and couldn't find anything useful.

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