MPI_T_PVAR_START(3)

💖 MPI_T_PVAR_START(3) — an Open MPI moment 💖

okay bestie, buckle up, because this one is literally the "on/off switch" of the MPI_T world and honestly? iconic. We're talking MPI_T_pvar_start and MPI_T_pvar_stop — the duo that starts and stops a performance variable. Yes, that's the whole vibe. Let's get into it ✨

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🌸 NAME 🌸

MPI_T_pvar_start, MPI_T_pvar_stop — start/stop a performance variable, no cap 🎀

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🦋 SYNTAX 🦋

💅 C Syntax

#include <mpi.h>

int MPI_T_pvar_start(MPI_T_pvar_session session, MPI_T_pvar_handle handle)

int MPI_T_pvar_stop(MPI_T_pvar_session session, MPI_T_pvar_handle handle)

like, that's it. two functions, four arguments total, absolutely serving minimalism 🫶

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⭐ INPUT PARAMETERS ⭐

• session — the performance experiment session. think of it as the group chat your variable is living in 💬
• handle — the performance variable handle. this is your little VIP pass to the specific variable you're obsessed with 🎟️

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🔥 DESCRIPTION 🔥

So MPI_T_pvar_start starts the performance variable whose handle you passed in handle. The way that works is literally just... you hand it the handle, it starts it. main character energy.

And here's the fun part: you can pass the special value MPI_T_PVAR_ALL_HANDLES in handle to start all non-continuous handles in the session specified in session. one call, whole squad activated. ate 💅✨

MPI_T_pvar_stop does the mirror-image thing — it stops the performance variable with the handle specified in handle. Same deal: the special value MPI_T_PVAR_ALL_HANDLES can be passed in handle to stop all non-continuous handles in the session specified in session. whole squad, but going to sleep 😴

⚠️ okay important caveat bestie, do NOT skip this: continuous performance variables can neither be started nor stopped. Like, they're always on. They don't need your help. They're built different. Trying to start/stop one is just not the move 🙈

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💀 ERRORS 💀

MPI_T_pvar_start and MPI_T_pvar_stop() will fail if:

• MPI_T_ERR_NOT_INITIALIZED — The MPI Tools interface not initialized. like, you gotta boot it up first, babe 🌱
• MPI_T_ERR_INVALID_SESSION — Session parameter is not a valid session. that session does not exist, fr fr 👻
• MPI_T_ERR_INVALID_HANDLE — Invalid handle or handle not associated with the session. wrong VIP pass, wrong party 🚫
• MPI_T_ERR_PVAR_NO_STARTSTOP — The variable cannot be started or stopped. see the continuous-variable thing above, it's giving "not that kind of variable" 💀

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🧚 SEE ALSO: 🧚

• MPI_T_pvar_get_info — go read this one next, it's the info desk of the pvar world 🌈

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👑 COPYRIGHT 👑

2003-2026, The Open MPI Community. protect it, cite it, love it 💜

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and that's the tea, bestie 🍓 — Open MPI, dated Sep 11, 2026, page MPI_T_PVAR_START(3), signed off with love from your favorite manual page 💖🎀🦋