Hp XC System 2.x Software Manuel d'utilisateur télécharger pdf (Page 113)

parallelism. For inform ation about running more complex applications, refer to the H P- M PI

user documentation.

8.3.2.1 E

xample Application hello_world

To quickly become familiar with compi lin g and running HP- M P I programs, start with the C

version of a familiar hello_world pro gram. This program is called hello_world.c and

prints out the text string “Hello world! I’m r of s on host”. I n this text string:

• r is the rank of the process

• s is the size of the co mmunicator

• host is the host on which the program is run

The processor n ame is the host name for this implementation.

The source code for hello_world.c is stored in $MPI_ROOT/help and is shown below.

#include <stdio.h>

include <mpi.h>

oid main(argc, argv)

nt argc; char *argv[];

{

t rank, size, len;

ar name[MPI_MAX_PROCESSOR_NAME];

MPI

_Init(&argc, &argv);

MPI

_Comm_rank(MPI_COMM_WORLD, &rank);

MPI

_Comm_size(MPI_COMM_WORLD, &size);

MPI

_Get_processor_name(name, &len);

prin

tf("Hello world! I’m %d of %d on %s\n", rank, size, name);

MPI_

Finalize();

exit

(0);

}

8.3.2.2 Building and Running hello_world

To build and run hello_world.c on a local host, n amed penguin2 in this example,

perform the following steps:

1. Change to a writable directory.

2. Compile the hello_world executable file:

$ $MPI_ROOT/bin/mpicc -o hello_world $MPI_ROOT/help/hello_world.c

If /opt/hpmpi/bin is in the PATH, a s it should be, this command can be simplified to

the following:

$ mpicc -o hello_world $MPI_ROOT/help/hello_world.c

3. Run the hello_world executable f ile:

$ $MPI_ROOT/bin/mpirun -srun -n4 hello_world

If /opt/hpmpi/bin is in the PATH, this command can be sim plified to the following:

$ mpirun -srun -n4 hello_world

In this comm and, -n4 specifies that the number of processes to run is four, and the

allocated nodes from SLURM are to be used.

4. Analyze hello_world output.

HP-MPI prints the output from running the hello_world executable in nondetermin istic

order. The following is an example of the output:

Using HP-MPI 8-3

1 2 ... 108 109 110 111 112 113 114 115 116 117 118 ... 153 154

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