MPI_Put(3)

NAME
MPI_Put, MPI_Rput - Copies data from the origin memory to the target.

SYNTAX

C Syntax
#include <mpi.h>
MPI_Put(const 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_Rput(const 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)
INCLUDE 'mpif.h'
MPI_PUT(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_RPUT(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

C++ Syntax
#include <mpi.h>
void MPI::Win::Put(const void* origin_addr, int origin_count, const
	MPI::Datatype& origin_datatype, int target_rank, MPI::Aint
	target_disp, int target_count, const MPI::Datatype&
	target_datatype) const

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 start of window to target buffer (nonnegative integer).

target_count
    Number of entries in target buffer (nonnegative integer).

target_datatype
    Data type of each entry in target buffer (handle).

win Window object used for communication (handle).

OUTPUT PARAMETER

request
    MPI_Rput: RMA request

IERROR
    Fortran only: Error status (integer).

DESCRIPTION
MPI_Put transfers origin_count successive entries of the type specified by origin_datatype, starting at address origin_addr on the origin node to the target node specified by the win, target_rank pair. The data are written in the target buffer at address target_addr = window_base + target_disp x disp_unit, where window_base and disp_unit are the base address and window displacement unit specified at window initialization, by the target process.

The target buffer is specified by the arguments target_count and target_datatype.

The data transfer is the same as that which would occur if the origin process executed a send operation with arguments origin_addr, origin_count, origin_datatype, target_rank, tag, comm, and the target process executed a receive operation with arguments target_addr, target_count, target_datatype, source, tag, comm, where target_addr is the target buffer address computed as explained above, and comm is a communicator for the group of win.

The communication must satisfy the same constraints as for a similar message-passing communication. The target_datatype may not specify overlapping entries in the target buffer. The message sent must fit, without truncation, in the target buffer. Furthermore, the target buffer must fit in the target window. In addition, only processes within the same buffer can access the target window.

The target_datatype argument is a handle to a datatype object defined at the origin process. However, this object is interpreted at the target process: The outcome is as if the target datatype object were defined at the target process, by the same sequence of calls used to define it at the origin process. The target data type must contain only relative displacements, not absolute addresses. The same holds for get and accumulate.

MPI_Rput is similar to MPI_Put, except that it allocates a communication request object and associates it with the request handle (the argument request). The completion of an MPI_Rput operation (i.e., after the corresponding test or wait) indicates that the sender is now free to update the locations in the origin_addr buffer. It does not indicate that the data is available at the target window. If remote completion is required, MPI_Win_flush, MPI_Win_flush_all, MPI_Win_unlock, or MPI_Win_unlock_all can be used.

NOTES
The target_datatype argument is a handle to a datatype object that is defined at the origin process, even though it defines a data layout in the target process memory. This does not cause problems in a homogeneous or heterogeneous environment, as long as only portable data types are used (portable data types are defined in Section 2.4 of the MPI-2 Standard).

The performance of a put transfer can be significantly affected, on some systems, from the choice of window location and the shape and location of the origin and target buffer: Transfers to a target window in memory allocated by MPI_Alloc_mem may be much faster on shared memory systems; transfers from contiguous buffers will be faster on most, if not all, systems; the alignment of the communication buffers may also impact performance.

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. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI::Exception object.

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_Get MPI_Rget
MPI_Accumulate MPI_Win_flush MPI_Win_flush_all MPI_Win_unlock MPI_Win_unlock_all