SHMEM_IGET64(3)

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💅 SHMEM_IGET64(3) — like, the strided-get glow-up

okay so bestie, welcome to the <pink>Open MPI</pink> manual page for SHMEM_IGET64(3) and its whole extended friend group 🫶. Pull up a chair, grab a strawberry 🍓, and let's get into it.

✨ NAME ✨

shmem_complex_iget(3), shmem_double_iget(3), shmem_float_iget(3), shmem_iget4(3), shmem_iget8(3), shmem_iget32(3), shmem_iget64(3), shmem_iget128(3), shmem_int_iget(3), shmem_integer_iget(3), shmem_logical_iget(3), shmem_long_iget(3), shmem_longdouble_iget(3), shmem_longlong_iget(3), shmem_real_iget(3), shmem_short_iget(3) — Transfers strided data from a specified processing element (PE). that's the whole vibe, periodt. 👑

🌸 SYNOPSIS 🌸

C or C++:

#include <mpp/shmem.h>

void shmem_iget32(void *target, const void *source,
  ptrdiff_t tst, ptrdiff_t sst, size_t len, int pe)

void shmem_iget64(void *target, const void *source,
  ptrdiff_t tst, ptrdiff_t sst, size_t len, int pe)

void shmem_iget128(void *target, const void *source,
  ptrdiff_t tst, ptrdiff_t sst, size_t len, int pe)

void shmem_int_iget(int *target, const int *source,
  ptrdiff_t tst, ptrdiff_t sst, size_t len, int pe)

void shmem_double_iget(double *target, const double *source,
  ptrdiff_t tst, ptrdiff_t sst, size_t len, int pe)

void shmem_float_iget(float *target, const float *source,
  ptrdiff_t tst, ptrdiff_t sst, size_t len, int pe)

void shmem_long_iget(long *target, const long *source,
  ptrdiff_t tst, ptrdiff_t sst, size_t len, int pe)

void shmem_longdouble_iget(long double *target,
  const long double *source, ptrdiff_t tst, ptrdiff_t sst,size_t len, int pe)

void shmem_longlong_iget(long long *target,
  const long long *source, ptrdiff_t tst, ptrdiff_t sst, size_t len, int pe)

void shmem_short_iget(short *target,
  const short *source, ptrdiff_t tst, ptrdiff_t sst, size_t len, int pe)

Fortran:

INCLUDE "mpp/shmem.fh"

INTEGER tst, sst, len, pe

CALL SHMEM_COMPLEX_IGET(target, source, tst, sst, len,
& pe)

CALL SHMEM_DOUBLE_IGET(target, source, tst, sst, len,
& pe)

CALL SHMEM_IGET4(target, source, tst, sst, len, pe)

CALL SHMEM_IGET8(target, source, tst, sst, len, pe)

CALL SHMEM_IGET32(target, source, tst, sst, len, pe)

CALL SHMEM_IGET64(target, source, tst, sst, len, pe)

CALL SHMEM_IGET128(target, source, tst, sst, len, pe)

CALL SHMEM_INTEGER_IGET(target, source, tst, sst, len,
& pe)

CALL SHMEM_LOGICAL_IGET(target, source, tst, sst, len,
& pe)

CALL SHMEM_REAL_IGET(target, source, tst, sst, len, pe)

🦋 DESCRIPTION 🦋

So the strided get routines do exactly what it says on the tin, bestie: they grab array data that's chillen at address source on the remote PE (pe). The elements in the source array aren't all squished together — they're separated by a stride, sst. Once the data arrives, it goes into the local memory address target, separated by stride tst. And the routines return after the data has been copied into your local target array — so like, when they come back, it's done, no cap. ✨

Here's the cast of characters (the arguments, iykyk):

  • target — the array on the local PE that's getting updated. this is the main character of the operation tbh 👑
  • source — the array holding the data to be copied, sitting over there on the remote PE.
  • tst — the stride between consecutive elements of the target array. It gets scaled by the element size of the target array. A value of 1 means contiguous data (all cozy together 💖). tst must be of type integer. If you're calling from Fortran, it has to be a default integer value.
  • sst — the stride between consecutive elements of the source array. Scaled by the element size of the source array. A value of 1 means contiguous data. sst must be of type integer. If you're in Fortran, it must be a default integer value.
  • len — the number of elements in the target and source arrays. len must be of type integer. Fortran girlies: 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. Fortran girlies: constant, variable, or array element of default integer type.

the typing constraints (these are non-negotiable, fr fr)

The target and source data objects have to conform to the typing constraints, which are literally these:

  • shmem_iget32, shmem_iget4 — any noncharacter type that has a storage size equal to 32 bits.
  • shmem_iget64, shmem_iget8 — any noncharacter type that has a storage size equal to 64 bits.
  • shmem_iget128 — any noncharacter type that has a storage size equal to 128 bits.
  • shmem_short_iget — elements of type short.
  • shmem_int_iget — elements of type int.
  • shmem_long_iget — elements of type long.
  • shmem_longlong_iget — elements of type long long.
  • shmem_float_iget — elements of type float.
  • shmem_double_iget — elements of type double.
  • shmem_longdouble_iget — elements of type long double.
  • SHMEM_COMPLEX_IGET — elements of type complex of default size.
  • SHMEM_DOUBLE_IGET — (Fortran) elements of type double precision.
  • SHMEM_INTEGER_IGET — elements of type integer.
  • SHMEM_LOGICAL_IGET — elements of type logical.
  • SHMEM_REAL_IGET — elements of type real.

and then, because the original page is being extra 💀:

  • shmem_longdouble_iget — elements of type long double.
  • SHMEM_COMPLEX_IGET — elements of type complex of default size.
  • SHMEM_DOUBLE_IGET — (Fortran) elements of type double precision.
  • SHMEM_INTEGER_IGET — elements of type integer.
  • SHMEM_LOGICAL_IGET — elements of type logical.
  • SHMEM_REAL_IGET — elements of type real.
not me listing those twice 😭 — but that's literally how the original has it, so we keep it. identical info, zero facts lost, that's the rule bestie.

If you're in Fortran, data types must be of default size. For example, a real variable must be declared as REAL, REAL*4, or REAL(KIND=4). no fancy wide sizes, okay? 🙈

🎀 NOTES 🎀

Go read intro_shmem(3) for the definition of the term remotely accessible — it's the whole lore, iykyk. 📖

🔥 EXAMPLES 🔥

okay so here's a cute little Fortran example that uses shmem_logical_iget. Compile this one with the -lsma compiler option, bestie 🫶

PROGRAM STRIDELOGICAL
  LOGICAL SOURCE(10), TARGET(5)
  SAVE SOURCE ! SAVE MAKES IT REMOTELY ACCESSIBLE
  DATA SOURCE /.T.,.F.,.T.,.F.,.T.,.F.,.T.,.F.,.T.,.F./
  DATA TARGET / 5*.F. /

  CALL START_PES(2)
  IF (MY_PE() .EQ. 0) THEN
    CALL SHMEM_LOGICAL_IGET(TARGET, SOURCE, 1, 2, 5, 1)
    PRINT*,'TARGET AFTER SHMEM_LOGICAL_IGET:',TARGET
  ENDIF
  CALL SHMEM_BARRIER_ALL
END

like, the SAVE comment is doing so much work there — it's literally what makes it remotely accessible. iconic. 🌟

💜 SEE ALSO 💜

2003-2026, The Open MPI Community

and that's the page, bestie 🦋 — brought to you by the <pink>Open MPI</pink> girlies, dated May 14, 2026, with all the love in the world. mwah 💋 go get those strides. 🎀

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