SHMEM_SET_CACHE_LINE_INV(3)

💖 SHMEM_SET_CACHE_LINE_INV(3) — Open MPI, section 3 💖

okay bestie, sit DOWN because we're talking about cache coherency today and honestly? it's giving ✨control✨

this lil family of routines is the data cache utilities crew: shmem_clear_cache_inv, shmem_set_cache_inv, shmem_set_cache_line_inv, shmem_udcflush, and shmem_udcflush_line. yes they all show up here, they're a package deal, no gatekeeping 🌸

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✨ SYNOPSIS ✨

🩷 C or C++

#include <mpp/shmem.h>

void shmem_clear_cache_inv(void)
void shmem_clear_cache_line_inv(void *target)
void shmem_set_cache_inv(void)
void shmem_set_cache_line_inv(void *target)
void shmem_udcflush(void)
void shmem_udcflush_line(void *target)

🩷 Fortran

INCLUDE "mpp/shmem.fh"

CALL SHMEM_CLEAR_CACHE_INV
CALL SHMEM_CLEAR_CACHE_LINE_INV(target)
CALL SHMEM_SET_CACHE_INV
CALL SHMEM_SET_CACHE_LINE_INV(target)

CALL SHMEM_UDCFLUSH
CALL SHMEM_UDCFLUSH_LINE(target)

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💅 DESCRIPTION 💅

okay so there's one argument that gets passed to the cache line control routines and she is iconic:

• target — a data object that is local to the processing element (PE). target can be of any noncharacter type. and if you're in Fortran land, she can be of any kind 🫶

now the tea on each routine:

• shmem_clear_cache_inv (3) — disables automatic cache coherency mode that was previously enabled by shmem_set_cache_inv (3) or shmem_set_cache_line_inv. turning it OFF, bestie, lights out 💀
• shmem_clear_cache_line_inv (3) — disables automatic cache coherency mode for the cache line associated with the address of target only. just that one line, not everybody, very targeted behavior slay
• shmem_set_cache_inv (3) — enables the OpenSHMEM API to automatically decide the best strategy for cache coherency. she's the main character making the calls 👑
• shmem_set_cache_line_inv — enables automatic cache coherency mode for the cache line associated with the address of target only. again, just that one line, bc we're precise here
• shmem_clear_cache_inv (3) — disables automatic cache coherency mode previously enabled by shmem_set_cache_inv (3) or shmem_set_cache_line_inv. and yeah, the page literally says this twice, i'm not playing, it's in the source like that, so here it is again, no cap 🙈
• shmem_udcflush (3) — makes the entire user data cache coherent. the whole thing. all of it. periodt
• shmem_udcflush_line (3) — makes coherent the cache line that corresponds with the address specified by target. one line only, cute and specific 🎀

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📝 NOTES 📝

these routines have been retained for improved backward compatibility with legacy architectures. so like, they're still here serving looks for the old-school crowd 🧚 not new-new, but definitely still on the roster.

bestie reminder: retained for backward compatibility with legacy architectures. that's the whole vibe of this notes section, no cap.

See also: intro_shmem(3) shmem_put(3) shmem_swap(3)

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🎀 Copyright 🎀

2003-2026, The Open MPI Community

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and that's the whole page, bestie!! 💖 this came to you straight from the Open MPI manual, dated Sep 10, 2026, courtesy of those Open MPI girlies at SHMEM_SET_CACHE_LINE_INV(3). go make your cache coherent, ily, bye 🦋✨💜