MPI_T_CVAR_WRITE(3)

💫 MPI_T_CVAR_WRITE(3) 💫

okay so bestie, welcome to MPI_T_CVAR_WRITE — yes that's the page name, and yes it's from the Open MPI manual collection, we love a documented function fr fr.

This whole page is about MPI_T_cvar_write — the little function that writes the value of a bound control variable. That's it. That's the whole vibe. 🎀

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✨ SYNOPSIS ✨

🌸 C Syntax

#include <mpi.h>

int MPI_T_cvar_write(MPI_T_cvar_handle handle, const void *buf)

that's the whole signature, no notes, she's tidy 💅

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🫶 INPUT PARAMETERS 🫶

• handle — the handle of the control variable you wanna write to. like, which one are we setting, bestie? 👑
• buf — the initial address of the storage location for the variable value. basically: where your new value lives 💖

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🦋 DESCRIPTION 🦋

okay so here's the tea ☕ — MPI_T_cvar_write sets the value of the control variable identified by the handle that you passed in handle, pulling that new value from the buffer you provided in buf. iconic behavior, honestly.

the caller must ensure that the buffer specified in buf is large enough to hold the entire value of the control variable. like, not me stressing about buffer sizes 😭 do NOT skimp on the space, she needs room to breathe.

and here's the part you can't skip 🫵 — if the variable has global scope, any write call must be issued on all connected MPI processes. all of them. every single one. no lurking in the group chat while everyone else writes.

want more deets? for more information see MPI-3 section 14.3.6. iykyk 📖✨

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💀 ERRORS 💀

MPI_T_cvar_write will fail if:

• MPI_T_ERR_NOT_INITIALIZED — the MPI Tools interface not initialized 🙈 (girl, boot it up first)
• MPI_T_ERR_INVALID_HANDLE — the handle is invalid 💅 that handle is not giving what it needs to give
• MPI_T_ERR_CVAR_SET_NOT_NOW — variable cannot be set at this moment ⏳ wrong time, wrong energy
• MPI_T_ERR_CVAR_SET_NEVER — variable cannot be set until end of execution 🌙 like... it's just never happening right now, it's a whole "wait until the end" situation

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🌈 SEE ALSO 🌈

• MPI_T_cvar_handle_alloc
• MPI_T_cvar_get_info

go read those too, they're the supporting cast and they ate 🔥

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👑 COPYRIGHT 👑

2003-2026, The Open MPI Community — legends only, periodt 💜

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and that's the page bestie!! 🎀 written down for Sep 11, 2026, straight from the Open MPI girlies — now go forth and write those control variables responsibly, mwah 🫶✨🌸