SHMEM_CHAR_GET(3)

📦
version 5.0.10 · 7 versions
, in ubuntu stonking

🎀 SHMEM_CHAR_GET(3) 🎀

okay bestie, sit down, hydrate, because this page is from the Open MPI manual (section 3, she's a library call, obviously 💅) and she's actually not scary at all. It's just a whole friend group of shmem_get routines that all do the same iconic thing. Let's get into it. ✨

🌸 NAME 🌸

Meet the squad — every single one of these is the same function wearing a different outfit, and they all transfer data from a specified processing element (PE):

no cap, that's the whole name section. 🫶

✨ SYNOPSIS ✨

💜 C or C++

#include <mpp/shmem.h>

void shmem_get32(void *target, const void *source,
  size_t len, int pe)

void shmem_get64(void *target, const void *source,
  size_t len, int pe)

void shmem_get128(void *target, const void *source,
  size_t len, int pe)

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

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

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

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

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

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

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

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

🦋 Fortran

INCLUDE "mpp/shmem.fh"

INTEGER len, pe

CALL SHMEM_CHARACTER_GET(target, source, len, pe)

CALL SHMEM_COMPLEX_GET(target, source, len, pe)

CALL SHMEM_DOUBLE_GET(target, source, len, pe)

CALL SHMEM_GET4(target, source, len, pe)

CALL SHMEM_GET8(target, source, len, pe)

CALL SHMEM_GET32(target, source, len, pe)

CALL SHMEM_GET64(target, source, len, pe)

CALL SHMEM_GET128(target, source, len, pe)

CALL SHMEM_GETMEM(target, source, len, pe)

CALL SHMEM_INTEGER_GET(target, source, len, pe)

CALL SHMEM_LOGICAL_GET(target, source, len, pe)

CALL SHMEM_REAL_GET(target, source, len, pe)

💖 DESCRIPTION 💖

So here's the tea ☕ — the shmem_get routines transfer nelems elements of the data object sitting at address source on the remote PE pe, over to the data object at address target on the local PE. And the way these routines are set up? They only return after the data has actually been copied to target on the local PE. So you're not getting some "lol maybe later" async nonsense — it's done when it says it's done. 💅

the arguments, bestie 🎀

  • target — Local data object to be updated. She's the one getting the glow-up.
  • source — The data object on the PE identified by pe that contains the data to be copied. Heads up: this data object must be remotely accessible.
  • len — Number of elements in the target and source arrays. len must be of type integer. If you're in Fortran, it has to be a constant, a variable, or an array element of default integer type.
  • pe — PE number of the remote PE. pe must be of type integer. If you're in Fortran, it has to be a constant, a variable, or an array element of default integer type.

typing constraints (aka the vibe check) 🌈

The target and source data objects have to conform to these, no exceptions:

  • shmem_getmem: Fortran: Any noncharacter type. C: Any data type. len is scaled in bytes.
  • shmem_get4, shmem_get32: Any noncharacter type that has a storage size equal to 32 bits.
  • {shmem_get8, shmem_get64}: Any noncharacter type that has a storage size equal to 64 bits.
  • shmem_get128: Any noncharacter type that has a storage size equal to 128 bits.
  • shmem_short_get: Elements of type short.
  • shmem_int_get: Elements of type int.
  • shmem_long_get: Elements of type long.
  • shmem_longlong_get: Elements of type long long.
  • shmem_float_get: Elements of type float.
  • shmem_double_get: Elements of type double.
  • shmem_longdouble_get: Elements of type long double.
  • SHMEM_CHARACTER_GET: Elements of type character. len is the number of characters to transfer. The actual character lengths of the source and target variables are ignored.
  • SHMEM_COMPLEX_GET: Elements of type complex of default size.
  • SHMEM_DOUBLE_GET: (Fortran) Elements of type double precision.
  • SHMEM_INTEGER_GET: Elements of type integer.
  • SHMEM_LOGICAL_GET: Elements of type logical.
  • SHMEM_REAL_GET: Elements of type real.
🫶 psst — if you're in Fortran, data types must be of default size. So like, a real variable has to be declared as REAL, REAL*4, or REAL(KIND=4). No sneaky extra-precision surprises, okay?

📝 NOTES 📝

Go read intro_shmem(3) if you want the actual definition of the term remotely accessible — that's where the lore lives. 🔥

🌟 EXAMPLES 🌟

okay so picture this adorable little Fortran situation 👑

PROGRAM REDUCTION
  REAL VALUES, SUM
  COMMON /C/ VALUES
  REAL WORK

  CALL START_PES(0) ! ALLOW ANY NUMBER OF PES
  VALUES = MY_PE() ! INITIALIZE IT TO SOMETHING
  CALL SHMEM_BARRIER_ALL
  SUM = 0.0
  DO I = 0,NUM_PES()-1
    CALL SHMEM_REAL_GET(WORK, VALUES, 1, I)
    SUM = SUM + WORK
  ENDDO
  PRINT *, 'PE ', MY_PE(), ' COMPUTED SUM=', SUM
  CALL SHMEM_BARRIER_ALL
END

👀 See also:

intro_shmem(3) shmem_put(3) shmem_iget(3) shmem_quiet(3)

2003-2026, The Open MPI Community

and that's the whole page, bestie — no gatekeeping, no missing flags, every single routine accounted for. 🧚 this lil writeup is dated Sep 10, 2026, straight from the Open MPI girlies, and honestly? iconic. go forth and shmem_get responsibly. 💖✨🎀

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