Q-Logic IB6054601-00 D Manual De Usuario
3 – Using InfiniPath MPI
Getting Started with MPI
Getting Started with MPI
3-2
IB6054601-00 D
Q
These examples assume that:
■
Your cluster administrator has properly installed InfiniPath MPI and the
PathScale compilers.
PathScale compilers.
■
Your cluster’s policy allows you to use the
mpirun
script directly, without having
to submit the job to a batch queuing system.
■
You or your administrator has properly set up your
ssh
keys and associated files
on your cluster. See
and
for details on
ssh
administration.
To begin, copy the examples to your working directory:
$ cp /usr/share/mpich/examples/basic/* .
Next, create an MPI hosts file in the same working directory. It contains the host
names of the nodes in your cluster on which you want to run the examples, with
one host name per line. Name this file
names of the nodes in your cluster on which you want to run the examples, with
one host name per line. Name this file
mpihosts
. The contents can be in the
following format:
hostname1
hostname2
...
There is more information on the
mpihosts
file in
3.3.1
An Example C Program
InfiniPath MPI uses some shell scripts to find the appropriate include files and
libraries for each supported language. Use the script
libraries for each supported language. Use the script
mpicc
to compile an MPI
program in C and the script
mpirun
to execute it.
The supplied example program
cpi.c
computes an approximation to pi. First,
compile it to an executable named
cpi
.
$ mpicc -o cpi cpi.c
mpicc
, by default, runs the PathScale pathcc or gcc compiler, and is used for
both compiling and linking, exactly as you'd use the
pathcc
command.
NOTE:
Then, run it with several different specifications for the number of processes:
$ mpirun -np 2 -m mpihosts ./cpi
Process 0 on hostname1
Process 1 on hostname2
pi is approximately 3.1416009869231241,
Error is 0.0000083333333309
wall clock time = 0.000149