MPI_T_PVAR_START(3)

💖 MPI_T_PVAR_START 💖

okay bestie, gather round, because we're about to talk about the Open MPI manual — performance variables, to be exact. This little page covers two functions that are literally a matched set: MPI_T_pvar_start and MPI_T_pvar_stop. They do exactly what they sound like. Start. Stop. Iconic behaviour, no notes. ✨

---

🌸 SYNOPSIS 🌸

✨ 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. two lines. that's the whole vibe. 🎀

---

🫶 INPUT PARAMETERS 🫶

• session — the performance experiment session, aka the whole situation your performance variable is living in. 💅
• handle — the performance variable handle. it's giving "which one tho". 🦋

---

👑 DESCRIPTION 👑

MPI_T_pvar_start starts the performance variable with the handle specified in handle. and here's the slay: you can pass the special value MPI_T_PVAR_ALL_HANDLES in handle to start all the non-continuous handles in the session specified in session. one call, every handle, main character energy fr fr. 🔥

MPI_T_pvar_stop 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 the non-continuous handles in the session specified in session. 💜

⚠️ okay important, no cap: continuous performance variables can neither be started nor stopped. they're just out here living their continuous truth and you cannot touch that. periodt. 💀

---

😭 ERRORS 😭

MPI_T_pvar_start and MPI_T_pvar_stop() will fail if:

• MPI_T_ERR_NOT_INITIALIZED — the MPI Tools interface isn't initialized. like, bestie, we haven't even started. 🙈
• MPI_T_ERR_INVALID_SESSION — the session parameter is not a valid session. fake session, blocked. 🚫
• MPI_T_ERR_INVALID_HANDLE — invalid handle, or a handle that isn't associated with the session. wrong handle for the wrong room ngl. 😭
• MPI_T_ERR_PVAR_NO_STARTSTOP — the variable cannot be started or stopped. it said "no". 💅

---

🌈 SEE ALSO 🌈

• MPI_T_pvar_get_info — go get the info on your pvar, you deserve to know. 🧚

---

and that's the page!! copyright goes to 2003-2026, The Open MPI Community, this was the Open MPI manual page, and it was dated Sep 10, 2026. stay hydrated, read your man pages, and go start (and stop) some performance variables responsibly. mwah. 💖✨🎀🦋