# 17.3.1. Open MPI

Open MPI - General information

## 17.3.1.1. OPEN MPI

Open MPI is an open source implementation of MPI (message-passing interface), the industry-standard specification for writing message-passing programs. Message passing is a programming model that gives the programmer explicit control over interprocess communication.

The MPI specification was developed by the MPI Forum, a group of software developers, computer vendors, academics, and computer-science researchers whose goal was to develop a standard for writing message-passing programs that would be efficient, flexible, and portable.

The outcome, known as the MPI Standard, was first published in 1993; its most recent version (MPI-4.0) was published in June 2021. Open MPI includes all MPI 3.1-compliant routines.

For more information about Open MPI, see https://www.open-mpi.org.

The MPI standards are available at https://www.mpi-forum.org.

## 17.3.1.2. MAN PAGE SYNTAX

Man pages for Open MPI and Open MPI I/O routines are named according to C syntax, that is, they begin with the prefix `MPI_`, all in uppercase, and the first letter following the `MPI_` prefix is also uppercase. The rest of the letters in the routine are all lowercase, for example, MPI_Comm_get_attr.

## 17.3.1.3. ENVIRONMENT

To fine-tune your Open MPI environment, you can either use arguments to the mpirun or mpiexec commands, or you can use MCA parameters.

For more information on arguments, see the mpirun(1) man page.

For a complete listing of MCA parameters and their descriptions, issue the command `ompi_info --all`. See ompi_info(1) for more information.

## 17.3.1.4. ERRORS

See MPI Errors for details about error values.

See also

MPI_T mpirun(1) mpiexec(1) ompi_info(1)