[gmx-users] how to increase GMX_OPENMP_MAX_THREADS

[Schulz, Roland]

That's not my experience. In my experience , for single node runs, it is usually faster to use 72 OPENMP threads rather than using 72 (t)MPI threads.

Roland

> -----Original Message-----
> From: gromacs.org_gmx-users-bounces at maillist.sys.kth.se
> [mailto:gromacs.org_gmx-users-bounces at maillist.sys.kth.se] On Behalf Of
> Szilárd Páll
> Sent: Monday, February 25, 2019 7:31 AM
> To: Discussion list for GROMACS users <gmx-users at gromacs.org>
> Subject: Re: [gmx-users] how to increase GMX_OPENMP_MAX_THREADS
> 
> What are you trying to do? Using 72 threads per rank in most cases (except
> some extreme and unusual) will not be efficient at all. If you are sure that
> you still want to do that, you can override this at compile time using cmake -
> DGMX_OPENMP_MAX_THREADS=
> 
> 
> 
> --
> Szilárd
> 
> 
> On Thu, Feb 21, 2019 at 5:58 AM Lalehan Ozalp <lalehan.ozalp at gmail.com>
> wrote:
> 
> > Hello all,
> > I'd been running simulation with GROMACS 2018 using 72 open mpi
> > threads without problem until (I assume) it was updated to 2019
> > version. When I execute mdrun with option -nt 72 (which is the number
> > of cores of my
> > terminal) it says:
> >
> > "you are using 72 openmp threads, which is larger than
> > GMX_OPENMP_MAX_THREADS (64). Decrease the number of OpenMP
> threads or
> > rebuild GROMACS with a larger value for GMX_OPENMP_MAX_THREADS."
> >
> > In the documentation of GROMACS 2019 release, it's written:  "mdrun
> > can run with more than GMX_OPENMP_MAX_THREADS threads."
> >
> > Could you please help me how to get around this issue?
> >
> > Thank you in advance.
> > Lalehan
> > --
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