SHMEM_PUT64(3)

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💖 SHMEM_PUT64(3) 💖

okay bestie, so like — welcome to the Open MPI manual pages 🎀, and today we're talking about the whole put girlie squad. You know her, you love her: shmem_put64(3) and, like, literally all of her sisters. This is the page for:

NAME (the actual vibes): Transfers data to a specified processing element (PE). 🦋 That's it. That's the whole personality. She sends your little data babies over to another PE and she does it fast.

✨ 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. That's the whole thing, she's efficient.

But — and this is important, bestie — these routines start the remote transfer and may return before the data is actually delivered to the remote PE. She's like "yeah yeah I sent it, bye 💅" and dips before the package even lands. Iconic behavior, but plan accordingly.

⚠️ Also: the delivery of data into the data object on the destination PE from different put calls may occur in any order. Which means two successive put operations may deliver data out of order unless you sneak a call to shmem_fence(3) in between the two calls. No cap. Order is not guaranteed, protect your peace (and your data) with a fence.

🫶 The arguments (aka the girlies you're passing in)

  • target — The data object to be updated on the remote PE. This data object must be remotely accessible. Non-negotiable, she needs to be reachable.
  • source — The data object containing the data to be copied. The origin story ✨.
  • 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. (Fortran said be specific.)
  • pe — PE number of the remote PE. pe must be of type integer. Same Fortran deal: it must be a constant, variable, or array element of default integer type.

🧚 Typing constraints (vibe check for your data types)

The target and source data objects must conform to certain typing constraints, which are as follows:

  • 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. (she said don't worry 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). Periodt.

🎀 EXAMPLES 🎀

The following shmem_put example is for C/C++ programs:

#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]);
}

👀 See also:

2003-2026, The Open MPI Community

okay that's the whole page bestie, you ate that 🫶 go forth and put your data where it belongs, and remember: fence before you flex ✨

— with love, your girl at the bottom of the page, dated Sep 10, 2026, signed by the whole Open MPI community 💖🌈⭐

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