Gromacs MPI + OpenMP build with a single thread

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1

GROMACS version: 2022.3
GROMACS modification: No
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If I do a hybrid MPI + OpenMP build and set OMP_NUM_THREADS=1, will there be a significant performance difference with a version built purely with MPI only? Even if I only spawn one OpenMP thread, there will still be OpenMP overheads. I know I can run a simple benchmark, but the significant performance difference may only show on certain tests. Has anyone benchmarked these two different versions?

Regards,

2

I believe you will basically get the same performance for both cases. I am unaware of a performance impact of OpenMP if the number of OpenMP threads is set to one.