6.2. Execution command format

MPI program execution format by mpiexec command is as following.

$ mpiexec  opiton execution module execution module option

Note

Incompatible Points of mpiexec

The mpiexec command has been customized for use in the Supercomputer Fugaku, so it is partly incompatible with the one described in MPI Users Guide. This section describes the incompatible points of mpiexec.

Collection of Application Information

The following information of executed applications is collected for the sake of improvement of operation of the Supercomputer Fugaku:

  • Compiler information

  • Symbol table

  • Shared library information

  • MD5 hash checksum

  • Type and strings of executable file

You can inhibit information collection about your application by setting the following environment variable:

#PJM -x "APPLOG=NO"

Information collection is performed only at the beginning of mpiexec , so it does not affect the performance of running jobs. Also, it does not so much affect execution time of jobs.


mpiexec command option specification example

  • When running MPI programs in 8 parallelMPI (-n 8)

$ mpiexec -n 8 -std-proc procfile ./a.out

Note

When -n option is omitted, default value is applied.

  • When running JAVA MPI programs in 8 parallel (-n 8)

$ mpiexec -n 8 -std-proc procfile java -classpath ./dir JavaTest

Note

Class path is specified with java command’s -classpath option.

  • If executes some MPI jobs at the same time

  1. MPMD

    It is possible to execute programs multiply by deviding execution unit with colon “:” . Sum of -n is set as not over --mpi proc=N.

    [Style]

    $ mpiexec [global options] -n N1 [local options] Execution file 1 : -n N2 [local options] Execution file 2 : ...

    [Example]

    Execute MPI program executable file a.out, b.out, c.out as per 2, 4, 6 parallel process

    $ mpiexec -std-proc procfile -n 2 ./a.out : -n 4 ./b.out : -n 6 ./c.out

    Attention

    If it’s Java program, execution by MPMD model is not guaranteed.

  2. Back ground job

    To sexecute some back groud jobs at the same time, specify the coordinates of the node to use by specifying -vcoordfile option. Be careful not to use the same node between jobs that run at the same time. You can run up to 128 at the same time in the background.