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A few very basic examples, perhaps use to test MPI-3 Fortran library functionality.

Free, popular MPI-3 interfaces for C and Fortran include:

• OpenMPI (Linux, Mac)
• MPICH (Linux, Mac)
• Intel MPI (Linux, Windows)

Fortran Coarraysare in a separate repo.

Build and self-test:

cmake --workflow default

or step-by-step

cmake -Bbuildcmake --build buildctest --test-dir build -V

This repo also gives an example of a workaround for OpenMPI 4.x and mpiexec race condition with large CPU count by setting TMPDIR to a short path name so as not to exceed 100 characters for UNIX sockets.

Pass data between two MPI threads.In this usage, MPI_Recv blocks waiting for MPI_Send

mpiexec -np 2 mpi/mpi_pass

SeeOpenMPI docsre: setting PATH and LD_LIBRARY_PATH if CMake has trouble finding OpenMPI for a compiler.

• https://hpc-forge.cineca.it/files/CoursesDev/public/2017/MasterCS/CalcoloParallelo/MPI_Master2017.pdf

FindMPI.cmake on Cray defines a rather sparse imported target MPI::MPI_C and MPI::MPI_Fortran like

-- Target: MPI::MPI_Fortran properties-- MPI::MPI_Fortran IMPORTED = TRUE-- MPI::MPI_Fortran NAME = MPI::MPI_Fortran-- MPI::MPI_Fortran SYSTEM = ON-- MPI::MPI_Fortran TYPE = INTERFACE_LIBRARY-- Target: MPI::MPI_C properties-- MPI::MPI_C IMPORTED = TRUE-- MPI::MPI_C NAME = MPI::MPI_C-- MPI::MPI_C SYSTEM = ON-- MPI::MPI_C TYPE = INTERFACE_LIBRARY

while on most non-Cray platforms the typical properties are also defined: INTERFACE_INCLUDE_DIRECTORIES, INTERFACE_LINK_LIBRARIES, INTERFACE_LINK_OPTIONS.Also on Cray. these typically defined variables are empty: MPI_Fortran_LIBRARIES, MPI_Fortran_MODULE_DIR, MPI_Fortran_INCLUDE_DIRS, MPI_Fortran_COMPILE_OPTIONS, MPI_Fortran_LINK_FLAGS.

If "mpi_f08.mod" is not found, typically the MPI include directories are also missing.You can manually check if mpi_f08.mod is preset under the include "-I" directories from:

mpif90 -show