SHMEM_DOUBLE_GET(3)

📦
version 5.0.10 · 4 versions
, in ubuntu stonking

💖 SHMEM_DOUBLE_GET(3) — the Open MPI girlies' guide 💖

okay bestie, so this is one of those pages in the Open MPI manual (section 3, aka library calls, iykyk) and it covers the whole get family at once. The page is titled SHMEM_DOUBLE_GET(3) but honestly she's a group chat, not a solo post. Here's everyone in the chat, all doing the exact same job: transferring data from a specified processing element (PE) 🦋

and what do they do? Transfers data from a specified processing element (PE). that's it, that's the job. periodt. 💅

✨ SYNOPSIS ✨

C or C++ girlies 🎀

#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 besties 🌸

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 the shmem_get routines transfer nelems elements of the data object at address source on the remote PE pe, over to the data object at address target on the local PE. and the way they come back to you? these routines return after the data has been copied to address target on the local PE. no dangling, no "check back later", it's done when it's done and then it returns. iconic behavior honestly 💖

the arguments, bestie 📝

  • target — Local data object to be updated. this is your lil glow-up slot on the local side.
  • source — Data object on the PE identified by pe that contains the data to be copied. This data object must be remotely accessible. (yes, that's a whole thing, we get to it in NOTES ✨)
  • len — Number of elements in the target and source arrays. len must be of type integer. If you are using Fortran, it must be a constant, variable, or array element of default integer type.
  • pe — PE number of the remote PE. pe must be of type integer. If you are using Fortran, it must be a constant, variable, or array element of default integer type.

typing constraints — the vibe check 🧚

the target and source data objects must conform to typing constraints, and bestie they are as follows:

  • 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. (hiii that's our main character on this page 👑)
  • 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.
🚨 Fortran girlies listen up: data types must be of default size. For example, a real variable must be declared as REAL, REAL*4, or REAL(KIND=4). no going off-script, fr fr.

📌 NOTES 📌

See intro_shmem(3) for a definition of the term remotely accessible. (yes bestie, it's a real defined term, go read her 💜)

🌈 EXAMPLES 🌈

okay picture this, a simple example for Fortran. it's giving reduction energy:

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, because we always shout out our friends:

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 cap, every flag, every type, every friend in the chat accounted for 💯

🦋 cute lil sign-off: this page came from the Open MPI manual, dated Sep 10, 2026, and lives at SHMEM_DOUBLE_GET(3). go get that data, you're built for this 💅✨
📦 where this page comes from