MPI_Get_hw_resource_info(3)

💖 MPI_Get_hw_resource_info(3) 💖

okay bestie so this is a page from the MPI manual, and we're about to get so cozy with your hardware. no cap.

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✨ NAME ✨

MPI_Get_hw_resource_info — returns an info object containing information pertaining to the hardware platform on which the calling MPI process is executing at the moment of the call.

like... it literally snitches on the hardware you're running on right now, at the exact moment the call goes down. the vibes are immaculate and the data is real. 🖥️✨

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🎀 SYNOPSIS 🎀

int MPI_Get_hw_resource_info(MPI_Info *hw_info)

that's it. that's the whole call. one arg. she's low-maintenance, she's iconic. 👑

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🦋 OUTPUT PARAMETERS 🦋

• hw_info — the info object that gets created (handle). she's fresh, she's new, she's yours now. you gotta handle her (literally, she's a handle) 💅

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🔥 THREAD AND INTERRUPT SAFETY 🔥

this routine is thread-safe. translation: multiple threads can use her at the same time, no user-provided thread locks needed, nobody's gotta hold the door. she's a sharer. 🫶

BUT. she is not interrupt safe. 😭 and the reason is usually that memory allocation routines like malloc (or other non-MPICH runtime routines) get used under the hood, and those babies are themselves not interrupt-safe. so like — threads? yes ma'am. interrupts? do not. 🙈

bestie, remember: thread-safe ≠ interrupt-safe. those are two totally different vibe checks.

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🧚 NOTES FOR FORTRAN 🧚

every MPI routine in Fortran (except for MPI_WTIME and MPI_WTICK) gets an extra argument tacked on the end: ierr. she's an integer, and she means the exact same thing as the return value of the routine in C. fortran really said "one more for the road." 🍓

in Fortran, MPI routines are subroutines, and you invoke them with the call statement.

also: all MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGER in Fortran. that's just the house rules. 🏠

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💀 ERRORS 💀

okay so all MPI routines (except MPI_Wtime and MPI_Wtick) return an error value — C routines as the value of the function, Fortran routines in that last argument. before that value comes back to you, the current MPI error handler gets called. and by default? that error handler aborts the MPI job. 😳 no soft launch, just yeet.

you can swap the error handler out:

• MPI_Comm_set_errhandler — for communicators
• MPI_File_set_errhandler — for files
• MPI_Win_set_errhandler — for RMA windows
• MPI_Errhandler_set — the MPI-1 routine, may be used but its use is deprecated ⚠️ (she's giving legacy, we don't stan)
• MPI_ERRORS_RETURN — the predefined error handler, use her if you want error values to actually come back instead of the job getting axed

heads up: MPI does not guarantee that an MPI program can continue past an error. however, MPI implementations will attempt to continue whenever possible. so like... maybe? no promises. 🤷

and now the error codes themselves:

• MPI_SUCCESS — no error; MPI routine completed successfully. slay. ✅
• MPI_ERR_ARG — invalid argument. some argument is invalid and is not identified by a specific error class (e.g., MPI_ERR_RANK). it's giving "something's wrong but nobody's naming names." 🫠
• MPI_ERR_OTHER — other error; use MPI_Error_string to get more information about this error code. she's a mystery, go interrogate her. 🔍

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🌈⭐💜 and that's the whole page, bestie, no cap, ate and left no crumbs 💜⭐🌈

this was the MPI manual's MPI_Get_hw_resource_info(3) page, dated 4/10/2026. mwah. go read your hardware's whole life story. 💅✨