MPICH
Overview
MPICH is a freely avaliable, portable implementation of MPI, the standard for message-passing libraries. MPICH runs over fast-ethernet on the machines that it is installed on. It is recommended that if you have code that is communication-intensive that you use one of the MPIs that use a high-speed network.
Setup
By default, most systems use a MPI implementation that is customized
for a high-speed interconnect rather than using straight MPICH.
If you would like to use MPICH instead, add
/usr/global/mpich/bin to the beginning of your PATH. Note that
MPICH will not use the high-speed interconnect and could
adversly impact the performace of your job runs.
Usage
There are two things to take into account in using
MPICH. The first is how to compile an MPI
program against it. The second is how to run the resulting
executable.
To compile against MPICH you should use
one of the compilation wrappers included with it. These wrappers
automatically add any necessary compilation arguments to your
compiler command to include the required MPICH
headers and libraries. Their syntax is as follows:
mpif77 -fc=f77_compiler -config=f77_compiler ...
mpif90 -f90=f90_compiler -config=f90_compiler ...
mpicc -cc=C_compiler -config=C_compiler ...
where f77_compiler,
f90_compiler, and C_compiler
are the names of any of the installed Fortran77, Fortran90, and C compilers
respectively. The "..." is the rest of the normal compilation line,
such as in:
mpif77 -fc=ifort -config=ifort foo.f -o foo
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A list of available compilers can be found in the 'Compilers and
Programming Tools' section of the HPC software pages. Examples of
the above commands can be found in the Examples section of this
page.
To run code that was compiled against the MPICH you
need to use
the command /usr/global/bin/mpirun in your PBS job
submission script. Its syntax is:
/usr/global/bin/mpirun executable_name
where executable_name is the name of your
MPICH executable.
An example PBS script can be found in the Examples
section of this page. Information on PBS scripts can be found in the
Users Guide for the system intended to be used.
Examples
For a Fortran77 MPI file foo.f that is intended to
be compiled with the Portland Group Fortran77 compiler to an executable
called foo, the following command would be used:
mpif77 -fc=pgf77 -config=pgf77 foo.f -o foo
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For a C MPI file foo.c that is intended to be
compiled with the Intel C Compiler to an executable called
foo, the following command would be used:
mpicc -cc=icc -config=icc foo.c -o foo
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An example PBS job submission script to run one of the above
foo executables over 4 nodes that have the Myrinet
interconnect using 2 processors per node for a maximum of 2 hours
would look like this:
#PBS -l nodes=4:ppn=2
#PBS -l walltime=2:00:00
#PBS -j oe
# change the current working directory to the directory where
# the executable file 'foo' can be found
cd /home/user/mpi
# run the executable file 'foo' using the qmpirun script
/usr/global/bin/mpirun ./foo
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Further information on PBS scripts and submitting jobs can be found in
Users Guide for the system that the job is intended to be run on.
Documentation
N/A
Please send questions or suggestions about this web page to beatnic@aset.psu.edu
ASET | ITS | Penn State
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