MPI_PCONTROL(3)

💅 MPI_PCONTROL(3) — the Open MPI glow-up ✨

okay bestie, welcome to the Open MPI corner of the manual, where we talk about MPI_Pcontrol — the lil function that controls profiling 🎀. no cap, it's giving "i do nothing but i enable everything" energy and honestly? iconic.

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🌸 NAME 🌸

MPI_Pcontrol — controls profiling. that's it, that's the whole job description bestie 💖

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✨ SYNTAX ✨

🧚 C Syntax

#include <mpi.h>

int MPI_Pcontrol(const int level, ... )

🦋 Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_PCONTROL(LEVEL)
     INTEGER LEVEL

🌈 Fortran 2008 Syntax

USE mpi_f08
MPI_Pcontrol(level)
     INTEGER, INTENT(IN) :: level

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🍓 INPUT PARAMETER 🍓

• level — the profiling level. this is the one (1) parameter that the standard actually tells you about, and even then it's highkey vibes-based 😭

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👑 DESCRIPTION 👑

okay so here's the tea 🫖: MPI libraries themselves make no use of this routine. they literally just return immediately to your user code. like, they're not even pretending to do work. but!! the presence of calls to this routine lets a profiling package get explicitly called by the user. so it's a little doorway, and who walks through it is up to you 🚪✨

since MPI has no control over how the profiling code is actually implemented, we literally cannot specify precisely what semantics calls to MPI_Pcontrol will provide. this vagueness extends to the number of arguments to the function and their datatypes — yes, it's that unserious 💀

but to give user codes some level of portability across different profiling libraries, we request the following meanings for certain values of level:

• level==0 — profiling is disabled.
• level==1 — profiling is enabled at a normal default level of detail.
• level==2 — profile buffers are flushed. (this may be a no-op in some profilers, so don't come for us 🙈)
• all other values of level — profile library-defined effects and additional arguments. iykyk 🧚

we also request that the default state after MPI_Init has been called is for profiling to be enabled at the normal default level — i.e., as if MPI_Pcontrol had just been called with the argument 1. this is the slay part: users can link with a profiling library and get profile output without having to modify their source code at all. zero edits, all the data, main character energy 👑

and the provision of MPI_Pcontrol as a no-op in the standard MPI library is what lets users modify their source code to get more detailed profiling info, while still being able to link exactly the same code against the standard MPI library. versatility!! we love to see it 🫶

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🔥 NOTES 🔥

this routine provides a common interface for profiling control. the interpretation of level and any other arguments is left to the profiling library. not us. we're just the messenger 💌

⚠️ important bestie: this function does not return an error value. consequently, the result of calling it before MPI_Init or after MPI_Finalize is undefined. so like... don't do that. that's the danger zone, no cap 💀

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🎀 COPYRIGHT 🎀

2003-2026, The Open MPI Community

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and that's the whole page, bestie 💜 tysm for reading — this has been Open MPI, MPI_PCONTROL(3), dated Sep 11, 2026. go forth and profile responsibly, mwah 🫶✨🌸