[gmx-developers] MPI with or without OpenMP

Berk Hess hess at kth.se
Thu Apr 23 10:42:30 CEST 2015


Always compile Gromacs with OpenMP. The user can decide at runtime to 
use one or more OpenMP threads. Using one thread will not result in 
measurable overhead compared to a non-OpenMP build.
Thread-MPI is our own drop-in thread based MPI implementation, which is 
designed to work together with OpenMP.

So make two builds:
Thread-MPI + OpenMP
MPI + OpenMP



On 04/23/2015 10:19 AM, Dominik 'Rathann' Mierzejewski wrote:
> Dear developers,
> I'm the new maintainer of Fedora packages of GROMACS.
> What is your recommendation regarding MPI-enabled builds:
> should I compile with thread-level (OpenMP) parallelization
> enabled or not?
> In another package I maintain, cp2k, there are separate builds
> with and without OpenMP.
> Also, what is the relation between GMX_THREAD_MPI and GMX_OPENMP?
> I guess both should not be enabled at the same time.
> Regards,

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