MPI(3)

MPI(3) — Open MPI general-information page, but make it cute 💖

🎀 NAME 🎀

• MPI — General information Open MPI gitclone. — yes, that’s the name line, bestie, and we’re keeping it exactly. 🎀

🌈 MPI 🌈

Okay so 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. You get the controls, bestie. 🎛️✨

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

The outcome, known as the MPI Standard, was first published in 1993; its most recent version (MPI-2) was published in July 1997. And Open MPI 1.2 includes all MPI 1.2-compliant and MPI 2-compliant routines. Periodt. 💅

For more information about Open MPI, see the following URL:

http://www.open-mpi.org

The MPI standards are available at the following URL:

http://www.mpi-forum.org

✨ MAN PAGE SYNTAX ✨

Man pages for Open MPI and Open MPI I/O routines are named according to C syntax. That means 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. Example: MPI_Comm_get_attr. The way that naming scheme is so consistent — obsessed. 🦋

🌸 ENVIRONMENT 🌸

To fine-tune your Open MPI environment, you have two routes, bestie: use arguments to the mpirun, orterun, or mpiexec commands, or use MCA parameters. Choose your fighter. 🌸

For more information on arguments, see the orterun.1 man page.

For a complete listing of MCA parameters and their descriptions, issue the command ompi_info -h or ompi_info -param all all. This information also appears in the FAQ on the Open MPI web site at:

http://www.open-mpi.org/faq/?category=tuning#mca-params

🔥 ERRORS 🔥

All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value. C routines return it as the value of the function; Fortran routines return it in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error. 😭

🚨 Read that again, bestie: by default, errors abort the job, and MPI does not guarantee that an MPI program can continue past an error. That’s not a vibe, that’s a caveat. 💀

For more information on Open MPI error codes, see mpi.h in the include directory.

Standard error return classes for Open MPI:

• MPI_SUCCESS — 0 — Successful return code. Slay. ✨
• MPI_ERR_BUFFER — 1 — Invalid buffer pointer.
• MPI_ERR_COUNT — 2 — Invalid count argument.
• MPI_ERR_TYPE — 3 — Invalid datatype argument.
• MPI_ERR_TAG — 4 — Invalid tag argument.
• MPI_ERR_COMM — 5 — Invalid communicator.
• MPI_ERR_RANK — 6 — Invalid rank.
• MPI_ERR_REQUEST — 7 — Invalid MPI_Request handle.
• MPI_ERR_ROOT — 8 — Invalid root.
• MPI_ERR_GROUP — 9 — Null group passed to function.
• MPI_ERR_OP — 10 — Invalid operation.
• MPI_ERR_TOPOLOGY — 11 — Invalid topology.
• MPI_ERR_DIMS — 12 — Illegal dimension argument.
• MPI_ERR_ARG — 13 — Invalid argument.
• MPI_ERR_UNKNOWN — 14 — Unknown error.
• MPI_ERR_TRUNCATE — 15 — Message truncated on receive.
• MPI_ERR_OTHER — 16 — Other error; use Error_string.
• MPI_ERR_INTERN — 17 — Internal error code.
• MPI_ERR_IN_STATUS — 18 — Look in status for error value.
• MPI_ERR_PENDING — 19 — Pending request.
• MPI_ERR_ACCESS — 20 — Permission denied.
• MPI_ERR_AMODE — 21 — Unsupported amode passed to open.
• MPI_ERR_ASSERT — 22 — Invalid assert.
• MPI_ERR_BAD_FILE — 23 — Invalid file name (for example, path name too long).
• MPI_ERR_BASE — 24 — Invalid base.
• MPI_ERR_CONVERSION — 25 — An error occurred in a user-supplied data-conversion function.
• MPI_ERR_DISP — 26 — Invalid displacement.
• MPI_ERR_DUP_DATAREP — 27 — Conversion functions could not be registered because a data representation identifier that was already defined was passed to MPI_REGISTER_DATAREP.
• MPI_ERR_FILE_EXISTS — 28 — File exists.
• MPI_ERR_FILE_IN_USE — 29 — File operation could not be completed, as the file is currently open by some process.
• MPI_ERR_FILE — 30 — Invalid file handle.
• MPI_ERR_INFO_KEY — 31 — Illegal info key.
• MPI_ERR_INFO_NOKEY — 32 — No such key.
• MPI_ERR_INFO_VALUE — 33 — Illegal info value.
• MPI_ERR_INFO — 34 — Invalid info object.
• MPI_ERR_IO — 35 — I/O error.
• MPI_ERR_KEYVAL — 36 — Illegal key value.
• MPI_ERR_LOCKTYPE — 37 — Invalid locktype.
• MPI_ERR_NAME — 38 — Name not found.
• MPI_ERR_NO_MEM — 39 — Memory exhausted.
• MPI_ERR_NOT_SAME — 40 — Collective argument not identical on all processes, or collective routines called in a different order by different processes.
• MPI_ERR_NO_SPACE — 41 — Not enough space.
• MPI_ERR_NO_SUCH_FILE — 42 — File (or directory) does not exist.
• MPI_ERR_PORT — 43 — Invalid port.
• MPI_ERR_QUOTA — 44 — Quota exceeded.
• MPI_ERR_READ_ONLY — 45 — Read-only file system.
• MPI_ERR_RMA_CONFLICT — 46 — Conflicting accesses to window.
• MPI_ERR_RMA_SYNC — 47 — Erroneous RMA synchronization.
• MPI_ERR_SERVICE — 48 — Invalid publish/unpublish.
• MPI_ERR_SIZE — 49 — Invalid size.
• MPI_ERR_SPAWN — 50 — Error spawning.
• MPI_ERR_UNSUPPORTED_DATAREP — 51 — Unsupported datarep passed to MPI_File_set_view.
• MPI_ERR_UNSUPPORTED_OPERATION — 52 — Unsupported operation, such as seeking on a file that supports only sequential access.
• MPI_ERR_WIN — 53 — Invalid window.
• MPI_T_ERR_MEMORY — 54 — Out of memory.
• MPI_T_ERR_NOT_INITIALIZED — 55 — Interface not initialized.
• MPI_T_ERR_CANNOT_INIT — 56 — Interface not in the state to be initialized.
• MPI_T_ERR_INVALID_INDEX — 57 — The enumeration index is invalid.
• MPI_T_ERR_INVALID_ITEM — 58 — The item index queried is out of range.
• MPI_T_ERR_INVALID_HANDLE — 59 — The handle is invalid.
• MPI_T_ERR_OUT_OF_HANDLES — 60 — No more handles available.
• MPI_T_ERR_OUT_OF_SESSIONS — 61 — No more sessions available.
• MPI_T_ERR_INVALID_SESSION — 62 — Session argument is not a valid session.
• MPI_T_ERR_CVAR_SET_NOT_NOW — 63 — Variable cannot be set at this moment.
• MPI_T_ERR_CVAR_SET_NEVER — 64 — Variable cannot be set until end of execution.
• MPI_T_ERR_PVAR_NO_STARTSTOP — 65 — Variable cannot be started or stopped.
• MPI_T_ERR_PVAR_NO_WRITE — 66 — Variable cannot be written or reset.
• MPI_T_ERR_PVAR_NO_ATOMIC — 67 — Variable cannot be read and written atomically.
• MPI_ERR_RMA_RANGE — 68 — Target memory is not part of the window (in the case of a window created with MPI_WIN_CREATE_DYNAMIC, target memory is not attached).
• MPI_ERR_RMA_ATTACH — 69 — Memory cannot be attached (e.g., because of resource exhaustion).
• MPI_ERR_RMA_FLAVOR — 70 — Passed window has the wrong flavor for the called function.
• MPI_ERR_RMA_SHARED — 71 — Memory cannot be shared (e.g., some process in the group of the specified communicator cannot expose shared memory).
• MPI_T_ERR_INVALID — 72 — Invalid use of the interface or bad parameter values(s).
• MPI_T_ERR_INVALID_NAME — 73 — The variable or category name is invalid.
• MPI_ERR_LASTCODE — 93 — Last error code.

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Footer sign-off, bestie: source/version is gitclone, the build label is Unreleased developer copy, and it points at MPI(3) — no date is listed in the footer, so don’t @ me for a timestamp. 💖✨🫶