GROMACS fails to detec HWLOC in OMPI

GROMACS version: 2020.5
GROMACS modification: No

Despite configuring with OpenMPI 4.0.5, which has HWLOC:

MCA hwloc: hwloc201 (MCA v2.1.0, API v2.0.0, Component v4.0.5)

GROMACS does not find HWLOC:

– Looking for HWLOC
– Looking for hwloc – hwloc.h not found
– Looking for hwloc – lib hwloc not found
– Could NOT find HWLOC (missing: HWLOC_LIBRARIES HWLOC_INCLUDE_DIRS) (Required is at least version “1.5”)

Does this matter in any way?

I also configured with HWLOC_DIR set to my own build of HWLOC, which eliminated the complaint; but it seems redundant to have two instances of HWLOC for the same build.

Not sure what you mean by this - you can successfully point to one of your installs but not the other?

Regardless, at the moment the only benefit of hwloc is better reporting of your hardware in log files, so feel free to proceed.

Your reply turned on a light: I will try rebuilding GROMACS configured with HWLOC_DIR set to ~openmpi-4.0.5_gcc-10.2.0/lib/openmpi/ to see if GROMACS accepts that.

Thank you!