[Gretl-devel] Re: MPI and OpenMP (and openblas?)

On Thu, 16 Jan 2020, Sven Schreiber wrote: > OK, so given our recent discussion about the problems of openblas > multithreading, the ranking of the timings is maybe not so surprising > anymore. But: why does OMP_NUM_THREADS=1 have an additional effect over > --omp-threads=1 when everything happens inside the MPI block ? > > I hope the problem was clearly explained. Just about -- but there's one thing I need to know: when the script is taking a relatively long time, do you or don't you have OMP_NUM_THREADS=4 set in the environment?