18.2.287. MPI_Put — Open MPI 5.0.1 documentation

# 18.2.287. MPI_Put

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

## 18.2.287.1. SYNTAX

### 18.2.287.1.1. 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)

### 18.2.287.1.2. Fortran Syntax

    USE MPI
    ! or the older form: 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

### 18.2.287.1.3. Fortran 2008 Syntax

    USE mpi_f08
    MPI_Put(origin_addr, origin_count, origin_datatype, target_rank,
                 target_disp, target_count, target_datatype, win, ierror)
         TYPE(*), DIMENSION(..), INTENT(IN), 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_Rput(origin_addr, origin_count, origin_datatype, target_rank,
         target_disp, target_count, target_datatype, win, request,
                 ierror)
         TYPE(*), DIMENSION(..), INTENT(IN), 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

## 18.2.287.2. 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).

## 18.2.287.3. OUTPUT PARAMETER

- `request`: MPI_Rput: RMA request

- `ierror`: Fortran only: Error status (integer).

## 18.2.287.4. 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.

## 18.2.287.5. 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.

## 18.2.287.6. ERRORS

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

Before the error value is returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) is called. If no communication object is associated with the MPI call, then the call is considered attached to MPI_COMM_SELF and will call the associated MPI error handler. When MPI_COMM_SELF is not initialized (i.e., before MPI_Init/MPI_Init_thread, after MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial error handler. The initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/MPI_Comm_spawn_multiple. If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all other MPI functions.

Open MPI includes three predefined error handlers that can be used:

- `MPI_ERRORS_ARE_FATAL` Causes the program to abort all connected MPI processes.

- `MPI_ERRORS_ABORT` An error handler that can be invoked on a communicator, window, file, or session. When called on a communicator, it acts as if MPI_Abort was called on that communicator. If called on a window or file, acts as if MPI_Abort was called on a communicator containing the group of processes in the corresponding window or file. If called on a session, aborts only the local process.

- `MPI_ERRORS_RETURN` Returns an error code to the application.

MPI applications can also implement their own error handlers by calling:

- MPI_Comm_create_errhandler then MPI_Comm_set_errhandler

- MPI_File_create_errhandler then MPI_File_set_errhandler

- MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init

- MPI_Win_create_errhandler then MPI_Win_set_errhandler

Note that MPI does not guarantee that an MPI program can continue past an error.

See the MPI man page for a full list of MPI error codes.

See the Error Handling section of the MPI-3.1 standard for more information.

See also

- MPI_Get

- MPI_Rget

- MPI_Accumulate

- MPI_Win_flush

- MPI_Win_flush_all

- MPI_Win_unlock

- MPI_Win_unlock_all