# Open MPI v6.1.0a1

Open MPI is an open source implementation of the Message Passing Interface (MPI) specification. This file indexes LLM-friendly documentation artifacts for this documentation version.

## About this file

This is the llms.txt for the "main" git branch (the development tip), which currently identifies itself as the Open MPI v6.1.x series. It is published at https://docs.open-mpi.org/en/main/ .

Open MPI publishes a separate set of these LLM-friendly artifacts for each documentation version. For Open MPI v5.0.0 and later they all follow the same URL scheme:

    https://docs.open-mpi.org/en/VERSION_SLUG/

where VERSION_SLUG is either:

- `main` --- the build from Open MPI's `main` git branch (the development tip); or
- `vA.B.C` --- where A and B are the major and minor version numbers. If C is `x` (e.g. `v6.1.x`) it is the build from that release branch; if C is an integer (e.g. `v6.1.0`) it is the build from that specific git-tagged release.

If you found this file but are looking for the LLM documentation of a different Open MPI version, substitute the desired VERSION_SLUG into the scheme above (for example, https://docs.open-mpi.org/en/main/llms.txt).

Documentation for Open MPI versions older than v5.0.0 is not published in this format; for those, see https://github.com/open-mpi/ompi/blob/v4.1.x/README , https://www.open-mpi.org/faq/ , and https://www.open-mpi.org/doc/ .

- The MPI Standard (https://www.mpi-forum.org/docs/) is authoritative for portable MPI semantics.
- `MPIX_*` and `OMPI_*` APIs are Open MPI extensions, not portable MPI Standard APIs.

## API catalog and corpora

- [Machine-readable API catalog (JSONL)](https://docs.open-mpi.org/en/main/llms/openmpi-mpi-api.jsonl)
- [Aggregate Markdown corpus](https://docs.open-mpi.org/en/main/llms/openmpi-mpi-api.md)
- [C interface](https://docs.open-mpi.org/en/main/llms/openmpi-mpi-api-c.md)
- [Fortran mpif.h interface](https://docs.open-mpi.org/en/main/llms/openmpi-mpi-api-fortran-mpifh.md)
- [Fortran use mpi interface](https://docs.open-mpi.org/en/main/llms/openmpi-mpi-api-fortran-use-mpi.md)
- [Fortran use mpi_f08 interface](https://docs.open-mpi.org/en/main/llms/openmpi-mpi-api-fortran-use-mpi-f08.md)
- [Interface selection guide](https://docs.open-mpi.org/en/main/llms/openmpi-mpi-interface-guide.md)
- [Curated examples](https://docs.open-mpi.org/en/main/llms/openmpi-mpi-examples.md)
- [Artifact manifest](https://docs.open-mpi.org/en/main/llms/openmpi-docs-manifest.json)

## Runtime introspection (installed Open MPI)

The artifacts above describe the MPI API for this version. To inspect a *specific* installation --- its exact version, build configuration, available MCA components, and the full set of run-time tunables (MCA parameters) --- run the `ompi_info` command on that installation; `ompi_info --all --parsable` emits a comprehensive, self-describing, machine-readable dump.

- [Runtime introspection with ompi_info](https://docs.open-mpi.org/en/main/llms/openmpi-runtime-introspection.md)

## Command man pages

- [mpirun.1](https://docs.open-mpi.org/en/main/llms/man-openmpi/man1/mpirun.1.md)
- [mpisync.1](https://docs.open-mpi.org/en/main/llms/man-openmpi/man1/mpisync.1.md)
- [ompi-wrapper-compiler.1](https://docs.open-mpi.org/en/main/llms/man-openmpi/man1/ompi-wrapper-compiler.1.md)
- [ompi_info.1](https://docs.open-mpi.org/en/main/llms/man-openmpi/man1/ompi_info.1.md)
- [opal_wrapper.1](https://docs.open-mpi.org/en/main/llms/man-openmpi/man1/opal_wrapper.1.md)

## Human-facing documentation

- [Building MPI applications](https://docs.open-mpi.org/en/main/building-apps/index.html)
- [Launching MPI applications](https://docs.open-mpi.org/en/main/launching-apps/index.html)
- [Tuning MPI applications](https://docs.open-mpi.org/en/main/tuning-apps/index.html)