MPI Libraries
On the HPC cluster, we have two different kinds of MPI libraries: OpenMPI and Intel MPI (impi)
The OpenMPI library is an open source implementation for the MPI protocol. The Intel MPI library is an optimized implementation for the MPI protocol. Different versions compiled with different compilers are available. A list is given by typing
module avail openmpi module avail impi
For performance reasons the latest release of OpenMPI / impi should be used.
Compiling with OpenMPI
Before compiling load the actual module of OpenMPI, e.g.
module load OpenMPI/2.1.1-GCC-6.4.0-2.28
for using the GNU compiler.
The compilation can be done by following wrappers of OpenMPI:
| Name | Description |
|---|---|
| mpicc | C compiler |
| mpic++, mpiCC or mpicxx | C++ compiler |
| mpif77 | Fortran 77 compiler |
| mpif90 | Fortran 90 compiler |
These programs are only wrappers which means that the scripts sets additional flags for OpenMPI (e.g. include path, flags for linking OpenMPI libraries, ...). For using the Intel Compiler please use the module
module load OpenMPI/2.1.0-iccifort-2018a
Below there is a list of all environment variables for setting other compiler.
| Environment variable | Description |
|---|---|
| OMPI_CC | Set the C compiler |
| OMPI_CXX | Sets the C++ compiler |
| OMPI_F77 | Sets the Fortran 77 compiler |
| OMPI_FC | Sets the Fortran 90 compiler |
Compiling with Intel MPI
Before compiling load the actual module of Intel MPI by
module load impi/2018a-iccifort-2018a
for Intel and
module load impi/2018a-GCC-6.4.0-2.28
for the GNU compiler. The compilation can be done by following wrappers of Intel MPI:
| Name | Description |
|---|---|
| mpicc | C compiler |
| mpicxx | C++ compiler |
| mpifc | Fortran compiler |
| mpif77 | Fortran 77 compiler |
| mpif90 | Fortran 90 compiler |
These programs are only wrappers which means that the scripts sets additional flags for Intel MPI (e.g. include path, flags for linking Intel MPI libraries, ...) use other compilers (e.g. GNU compiler, Intel Compiler). The compilers can be choosen by setting environment variables, e.g.
export I_MPI_CC=icc
for using the Intel C compiler. Below there is a list of all environment variables for setting the compiler.
| Environment variable | Description |
|---|---|
| I_MPI_CC | Set the C compiler for the mpicc script |
| I_MPI_CXX | Sets the C++ compiler for the mpicxx script |
| I_MPI_FC | Sets the Fortran for the mpifc script |
| I_MPI_F77 | Sets the Fortran 77 compiler for the mpif77 script |
| I_MPI_F90 | Sets the Fortran 90 compiler for the mpif90 script |
Alternatively for GNU compilers and Intel Compilers there exists following wrapper scripts which needs no special environment variables settings.
| Wrapper for Intel Compiler | Wrapper for GNU Compiler | Description |
|---|---|---|
| mpiicc | mpigcc | C compiler |
| mpiicpc | mpigxx | C++ compiler |
| mpiifort | Fortran 77 compiler |
