SHMEM_DOUBLE_PUT(3)

📦
version 5.0.10 · 4 versions
, in ubuntu stonking

💖 shmem_double_put(3) — Open MPI, bestie edition 💖

okay so listen. this is the Open MPI manual page for a whole family of put functions, and yes the page is named after shmem_double_put(3) but it's really a group chat. the whole squad is here:

and what do they all do? Transfers data to a specified processing element (PE). periodt. 👑

✨ SYNOPSIS ✨

C or C++:

#include <mpp/shmem.h>

void shmem_double_put(double *target, const double *source,
  size_t len, int pe)

void shmem_float_put(float *target, const float *source,
  size_t len, int pe)

void shmem_int_put(int *target, const int *source, size_t len,
  int pe)

void shmem_long_put(long *target, const long *source,
  size_t len, int pe)

void shmem_longdouble_put(long double *target,
  const long double *source, size_t len, int pe)

void shmem_longlong_put(long long *target,
  const long long *source, size_t len, int pe)

void shmem_put32(void *target, const void *source, size_t len,
  int pe)

void shmem_put64(void *target, const void *source, size_t len,
  int pe)

void shmem_put128(void *target, const void *source, size_t len,
  int pe)

void shmem_putmem(void *target, const void *source, size_t len,
  int pe)

void shmem_short_put(short *target, const short *source,
  size_t len, int pe)

Fortran:

INCLUDE "mpp/shmem.fh"

INTEGER len, pe

CALL SHMEM_CHARACTER_PUT(target, source, len, pe)

CALL SHMEM_COMPLEX_PUT(target, source, len, pe)

CALL SHMEM_DOUBLE_PUT(target, source, len, pe)

CALL SHMEM_INTEGER_PUT(target, source, len, pe)

CALL SHMEM_LOGICAL_PUT(target, source, len, pe)

CALL SHMEM_PUT(target, source, len, pe)

CALL SHMEM_PUT4(target, source, len, pe)

CALL SHMEM_PUT8(target, source, len, pe)

CALL SHMEM_PUT32(target, source, len, pe)

CALL SHMEM_PUT64(target, source, len, pe)

CALL SHMEM_PUT128(target, source, len, pe)

CALL SHMEM_PUTMEM(target, source, len, pe)

CALL SHMEM_REAL_PUT(target, source, len, pe)

🌸 DESCRIPTION 🌸

so here's the tea 🍓: these routines transfer nelems elements of the data object at address source on the calling PE, over to the data object at address target on the remote PE pe.

and here's the part that gets people every single time — these routines start the remote transfer and may return before the data is delivered to the remote PE. it's giving "sent the text, they haven't read it yet". it's async, bestie. that's the whole vibe. 💅

the delivery of data into the data object on the destination PE from different put calls may occur in any order. which means — and this is the important bit — two successive put operations may deliver data out of order unless a call to shmem_fence(3) is introduced between the two calls. no cap. fence first or chaos. 😭

the arguments are as follows, one by one:

  • target — the data object to be updated on the remote PE. this one must be remotely accessible. non-negotiable, it's the whole main character requirement. 👑
  • source — the data object containing the data to be copied.
  • len — number of elements in the target and source arrays. len must be of type integer. if you're in Fortran land, it must be a constant, variable, or array element of default integer type.
  • pe — the PE number of the remote PE. pe must be of type integer. and again, if you're using Fortran, it must be a constant, variable, or array element of default integer type.

🌈 the typing constraints 🌈

the target and source data objects must conform to certain typing constraints, which are as follows. read carefully, this is the vibe check:

  • shmem_putmem — Fortran: Any noncharacter type. C: Any data type. len is scaled in bytes.
  • shmem_put4, shmem_put32 — Any noncharacter type that has a storage size equal to 32 bits.
  • shmem_put8, shmem_put64 — Any noncharacter type that has a storage size equal to 64 bits.
  • shmem_put128 — Any noncharacter type that has a storage size equal to 128 bits.
  • shmem_short_put — Elements of type short.
  • shmem_int_put — Elements of type int.
  • shmem_long_put — Elements of type long.
  • shmem_longlong_put — Elements of type long long.
  • shmem_float_put — Elements of type float.
  • shmem_double_put — Elements of type double.
  • shmem_longdouble_put — Elements of type long double.
  • SHMEM_CHARACTER_PUT — Elements of type character. len is the number of characters to transfer. the actual character lengths of the source and target variables are ignored. yeah. ignored. don't think about it. 🙈
  • SHMEM_COMPLEX_PUT — Elements of type complex of default size.
  • SHMEM_DOUBLE_PUT — (Fortran) Elements of type double precision.
  • SHMEM_INTEGER_PUT — Elements of type integer.
  • SHMEM_LOGICAL_PUT — Elements of type logical.
  • SHMEM_REAL_PUT — Elements of type real.

If you are using Fortran, data types must be of default size. for example, a real variable must be declared as REAL, REAL*4, or REAL(KIND=4). ✨

🧚 EXAMPLES 🧚

the following shmem_put example is for C/C++ programs. look at her. she's doing amazing:

#include <stdio.h>
#include <mpp/shmem.h>

main()
{
  long source[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
  static long target[10];
  shmem_init();

  if (shmem_my_pe() == 0) {
    /* put 10 words into target on PE 1 */
    shmem_long_put(target, source, 10, 1);
  }
  shmem_barrier_all();  /* sync sender and receiver */
  if (shmem_my_pe() == 1)
    shmem_udcflush();  /* not required on Altix systems */
  printf("target[0] on PE %d is %d\n", shmem_my_pe(), target[0]);
}

okay a couple notes from your girl: shmem_barrier_all() is doing the sync-sender-and-receiver thing (iconic behaviour), and that shmem_udcflush() line — not required on Altix systems, iykyk. 🦋

👀 SEE ALSO 👀

💜 a lil sign-off 💜

Copyright 2003-2026, The Open MPI Community. that's the source, that's the people, they ate. 🫶

this edition landed Sep 10, 2026, and honestly? she was serving SHMEM_DOUBLE_PUT(3) the entire time. go fence your puts, bestie. mwah. 💅🎀⭐

📦 where this page comes from