[gmx-developers] MPI with or without OpenMP

[Berk Hess]

Hi,

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

Cheers,

Berk

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,