HPC/Applications/impi: Difference between revisions
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__NOTOC__ | |||
== Introduction == | == Introduction == | ||
Intel-MPI is based on MPICH2 and provides an MPICH2 runtime environment for precompiled binaries. | Intel-MPI is based on MPICH2 and provides an MPICH2 runtime environment for precompiled binaries. | ||
| Line 16: | Line 17: | ||
== IMPI vs. OpenMPI == | == IMPI vs. OpenMPI == | ||
Since the openmpi module is loaded by default, use the following instead of <code>module load impi</code>: | |||
module '''switch''' openmpi impi | |||
* openmpi is loaded second and is called using <code>mpirun</code>. | However, the modules can '''coexist at runtime''' if: | ||
* [[../#impi|'''impi''']] is loaded first and is called using <code>mpiexec.hydra</code>. | |||
* [[../#openmpi|'''openmpi''']] is loaded second and is called using <code>mpirun</code>. | |||
* binaries using impi are ''statically linked'', i.e., | * binaries using impi are ''statically linked'', i.e., | ||
ldd ''binary-using-impi'' | grep libmpi.so || echo OK | ldd ''binary-using-impi'' | grep libmpi.so || echo OK | ||
| Line 28: | Line 31: | ||
module load openmpi | module load openmpi | ||
; Caveat: This replaces possibly specific existing openmpi versions by the default version, which may break packages depending on it. | ; Caveat: This replaces possibly specific existing openmpi versions by the default version, which may break packages depending on it. | ||
; Why not load both modules by default?: | |||
: While many files in those distributions differ, major scripts and libraries use the same name: | |||
(cd $OMPI_HOME; ls -1 {bin,lib}/* ) > /tmp/ompi | (cd $OMPI_HOME; ls -1 {bin,lib}/* ) > /tmp/ompi | ||
(cd $IMPI_HOME; ls -1 {bin,lib}/* ) > /tmp/impi | (cd $IMPI_HOME; ls -1 {bin,lib}/* ) > /tmp/impi | ||
Revision as of 21:52, June 3, 2011
Introduction
Intel-MPI is based on MPICH2 and provides an MPICH2 runtime environment for precompiled binaries.
- See also
Process manager
Use the Hydra process manager (new since impi version 4.x). See sec. 2.4 Scalable Process Management System in the Reference Manual.
To do so, simply use mpiexec.hydra instead of the customary mpirun or mpiexec calls:
mpiexec.hydra \
-machinefile $PBS_NODEFILE \
-np $(wc -l < $PBS_NODEFILE) \
./a.out
With Hydra, you no longer need to set up and tear down the older and considerably less stable MPD manager.
IMPI vs. OpenMPI
Since the openmpi module is loaded by default, use the following instead of module load impi:
module switch openmpi impi
However, the modules can coexist at runtime if:
- impi is loaded first and is called using
mpiexec.hydra. - openmpi is loaded second and is called using
mpirun. - binaries using impi are statically linked, i.e.,
ldd binary-using-impi | grep libmpi.so || echo OK
- prints "OK".
- you don't attempt to compile software using the convenience wrappers like
mpicc, mpif90,etc. For these wrappers, the last module loaded will be active. It may be possible to use full paths like$IMPI_HOME/bin/mpif90, but this has not been tested fully.
- Since openmpi is loaded by default, use the following sequence in ~/.bashrc:
module unload openmpi module load impi module load openmpi
- Caveat
- This replaces possibly specific existing openmpi versions by the default version, which may break packages depending on it.
- Why not load both modules by default?
- While many files in those distributions differ, major scripts and libraries use the same name:
(cd $OMPI_HOME; ls -1 {bin,lib}/* ) > /tmp/ompi
(cd $IMPI_HOME; ls -1 {bin,lib}/* ) > /tmp/impi
comm -1 -2 /tmp/?mpi
rm /tmp/?mpi
bin/mpicc bin/mpicxx bin/mpiexec bin/mpif77 bin/mpif90 bin/mpirun lib/libmpi.so