How to tell if OpenMP is working?

Question

I am trying to run LIBSVM in parallel mode, however my question is in OpenMP in general. According to LIBSVM FAQ, I have modified the code with #pragma calls to use OpenMP. I al

Answer 1

You can use the function omp_get_num_threads(). It will return you the number of threads that are used by your program.

Answer 2

With omp_get_max_threads() you get the maximum number of threads available to your program. It is also the maximum of all possible return values of omp_get_num_threads(). You can explicitly set the number of threads to be used by your program with the environment variable OMP_NUM_THREADS, e.g. in bash via

$export OMP_NUM_THREADS=8; your_program