openmpi/ompi/mpi/man/man3/MPI_Get.md

Name

MPI_Get, MPI_Rget - Copies data from the target memory to the origin.

Syntax

C Syntax

#include <mpi.h>

MPI_Get(void *origin_addr, int origin_count, MPI_Datatype
    origin_datatype, int target_rank, MPI_Aint target_disp,
    int target_count, MPI_Datatype target_datatype, MPI_Win win)

MPI_Rget(void *origin_addr, int origin_count, MPI_Datatype
     origin_datatype, int target_rank, MPI_Aint target_disp,
     int target_count, MPI_Datatype target_datatype, MPI_Win win,
         MPI_Request *request)

Fortran Syntax (See Fortran 77 Notes)

USE MPI
! or the older form: INCLUDE 'mpif.h'

MPI_GET(ORIGIN_ADDR, ORIGIN_COUNT, ORIGIN_DATATYPE, TARGET_RANK,
    TARGET_DISP, TARGET_COUNT, TARGET_DATATYPE, WIN, IERROR)
    <type> ORIGIN_ADDR(*)
    INTEGER(KIND=MPI_ADDRESS_KIND) TARGET_DISP
    INTEGER ORIGIN_COUNT, ORIGIN_DATATYPE, TARGET_RANK,
    TARGET_COUNT, TARGET_DATATYPE, WIN, IERROR

MPI_RGET(ORIGIN_ADDR, ORIGIN_COUNT, ORIGIN_DATATYPE, TARGET_RANK,
     TARGET_DISP, TARGET_COUNT, TARGET_DATATYPE, WIN, REQUEST, IERROR)
     <type> ORIGIN_ADDR(*)
     INTEGER(KIND=MPI_ADDRESS_KIND) TARGET_DISP
     INTEGER ORIGIN_COUNT, ORIGIN_DATATYPE, TARGET_RANK,
     TARGET_COUNT, TARGET_DATATYPE, WIN, REQUEST, IERROR

Fortran 2008 Syntax

USE mpi_f08

MPI_Get(origin_addr, origin_count, origin_datatype, target_rank,
    	target_disp, target_count, target_datatype, win, ierror)
    TYPE(*), DIMENSION(..), ASYNCHRONOUS :: origin_addr
    INTEGER, INTENT(IN) :: origin_count, target_rank, target_count
    TYPE(MPI_Datatype), INTENT(IN) :: origin_datatype, target_datatype
    INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: target_disp
    TYPE(MPI_Win), INTENT(IN) :: win
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror

MPI_Rget(origin_addr, origin_count, origin_datatype, target_rank,
    target_disp, target_count, target_datatype, win, request,
    	ierror)
    TYPE(*), DIMENSION(..), ASYNCHRONOUS :: origin_addr
    INTEGER, INTENT(IN) :: origin_count, target_rank, target_count
    TYPE(MPI_Datatype), INTENT(IN) :: origin_datatype, target_datatype
    INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: target_disp
    TYPE(MPI_Win), INTENT(IN) :: win
    TYPE(MPI_Request), INTENT(OUT) :: request
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror

Input Parameters

• origin_addr : Initial address of origin buffer (choice).
• origin_count : Number of entries in origin buffer (nonnegative integer).
• origin_datatype : Data type of each entry in origin buffer (handle).
• target_rank : Rank of target (nonnegative integer).
• target_disp : Displacement from window start to the beginning of the target buffer (nonnegative integer).
• target_count : Number of entries in target buffer (nonnegative integer).
• target datatype : datatype of each entry in target buffer (handle)
• win : window object used for communication (handle)

Output Parameter

• request : MPI_Rget: RMA request
• IERROR : Fortran only: Error status (integer).

Description

MPI_Get copies data from the target memory to the origin, similar to MPI_Put, except that the direction of data transfer is reversed. The origin_datatype may not specify overlapping entries in the origin buffer. The target buffer must be contained within the target window, and the copied data must fit, without truncation, in the origin buffer. Only processes within the same node can access the target window.

MPI_Rget is similar to MPI_Get, except that it allocates a communication request object and associates it with the request handle (the argument request) that can be used to wait or test for completion. The completion of an MPI_Rget operation indicates that the data is available in the origin buffer. If origin_addr points to memory attached to a window, then the data becomes available in the private copy of this window.

Fortran 77 Notes

The MPI standard prescribes portable Fortran syntax for the TARGET_DISP argument only for Fortran 90. FORTRAN 77 users may use the non-portable syntax

INTEGER*MPI_ADDRESS_KIND TARGET_DISP

where MPI_ADDRESS_KIND is a constant defined in mpif.h and gives the length of the declared integer in bytes.

Errors

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.

Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

See Also

MPI_Put(3)