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MPI_Win_fence(3) LAM/MPI MPI_Win_fence(3)


MPI_Win_fence - Synchronizes one-sided communications on a window


#include <mpi.h>
MPI_Win_fence(int assertion, MPI_Win win)


- program assertion (integer)
- window object (handle)


The MPI call MPI_WIN_FENCE(assert, win) synchronizes RMA calls on win. The call is collective on the group of win. All RMA operations on win originating at a given process and started before the fence call will complete at that process before the fence call returns. They will be completed at their target before the fence call returns at the target. RMA operations on win started by a process after the fence call returns will access their target window only after MPI_WIN_FENCE has been called by the target process.

Calls to MPI_WIN_FENCE should both precede and follow calls to put, get or accumulate that are synchronized with fence calls.


All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have an additional argument ierr at the end of the argument list. ierr is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the call statement.

All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.


The IMPI standard only supports MPI-1 functions. Hence, this function is currently not designed to operate within an IMPI job.


If an error occurs in an MPI function, the current MPI error handler is called to handle it. By default, this error handler aborts the MPI job. The error handler may be changed with MPI_Errhandler_set ; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned (in C and Fortran; this error handler is less useful in with the C++ MPI bindings. The predefined error handler MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value needs to be recovered). Note that MPI does not guarantee that an MPI program can continue past an error.

All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as the value of the function and Fortran routines in the last argument. The C++ bindings for MPI do not return error values; instead, error values are communicated by throwing exceptions of type MPI::Exception (but not by default). Exceptions are only thrown if the error value is not MPI::SUCCESS .

Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI functions will return upon an error, there will be no way to recover what the actual error value was.

- No error; MPI routine completed successfully.
- Invalid window. A common error is to use a null window in a call.
- This error indicates than an operation has been attempted on a "closed" window. Certain one-sided operations can only be performed on windows whose epoch has been started with MPI_Win_start.
- Other error; use MPI_Error_string to get more information about this error code.

seealso MPI_Put(3), MPI_Get(3), MPI_Win_create(3), MPI_Win_start(3), MPI_Win_complete(3), MPI_Accumulate(3), MPI_Win_free(3), MPI_Win_get_group(3), MPI_Win_get_group(3), MPI_Win_wait(3)


For more information, please see the official MPI Forum web site, which contains the text of both the MPI-1 and MPI-2 standards. These documents contain detailed information about each MPI function (most of which is not duplicated in these man pages).



6/24/2006 LAM/MPI 7.1.4