[gmx-users] how to increase GMX_OPENMP_MAX_THREADS

Szilárd Páll pall.szilard at gmail.com
Mon Feb 25 16:31:22 CET 2019

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


On Thu, Feb 21, 2019 at 5:58 AM Lalehan Ozalp <lalehan.ozalp at gmail.com>

> 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
> --
> Gromacs Users mailing list
> * Please search the archive at
> http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before
> posting!
> * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
> * For (un)subscribe requests visit
> https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or
> send a mail to gmx-users-request at gromacs.org.

More information about the gromacs.org_gmx-users mailing list