[PerformanceJonesLLC]

Open MPI dropped C++ bindings from Version 5, but some OpenFOAM components require these; is there any chance OpenFOAM will adapt, so that it could benefit from Open MPI enhancements?

[olesen]

Originally Posted by PerformanceJonesLLC

Open MPI dropped C++ bindings from Version 5, but some OpenFOAM components require these; is there any chance OpenFOAM will adapt, so that it could benefit from Open MPI enhancements?

This is truly curious. To my knowledge there are absolutely no OpenFOAM components using C++ bindings for MPI. Everything is wrapped in an opaque layer (UPstream/Pstream) or in an opaque handle (UPstream::Request), each of which uses the C bindings.
Which components have you found??

[PerformanceJonesLLC]

Originally Posted by olesen

This is truly curious. To my knowledge there are absolutely no OpenFOAM components using C++ bindings for MPI. Everything is wrapped in an opaque layer (UPstream/Pstream) or in an opaque handle (UPstream::Request), each of which uses the C bindings.
Which components have you found??

The problem turned out to be in config.sh/mpi: in OMPI 5 the names of some tools have changed; with a simple change I was able to build OpenFOAM with OpenMPI 5.0.3.

[PerformanceJonesLLC]

Originally Posted by PerformanceJonesLLC

The problem turned out to be in config.sh/mpi: in OMPI 5 the names of some tools have changed; with a simple change I was able to build OpenFOAM with OpenMPI 5.0.3.

KaHIP was a red herring, but despite CMakeLists.txt I found no C++ MPI in it:


> find -name CMakeLists.txt -exec grep CXX {} /dev/null \; | grep MPI_CXX
./parallel/parallel_src/CMakeLists.txt:include_directories(${MPI_CXX_INCLU DE_PATH})
./parallel/parallel_src/CMakeLists.txt:link_libraries(OpenMP::OpenMP_CXX MPI::MPI_CXX)
./parallel/modified_kahip/CMakeLists.txt:include_directories(${MPI_CXX_INCLU DE_PATH})
./CMakeLists.txt: target_include_directories(libkaffpa_parallel PUBLIC ${MPI_CXX_INCLUDE_PATH})
./CMakeLists.txt: target_include_directories(kaffpaE PUBLIC ${MPI_CXX_INCLUDE_PATH})
./CMakeLists.txt: target_link_libraries(kaffpaE ${MPI_CXX_LIBRARIES} ${OpenMP_CXX_LIBRARIES} OpenMP::OpenMP_CXX )



Anyway the problem lay in OpenFOAM source, namely config.sh/mpi as already noted.