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MPI_Win_start(3) man page (version 1.10.1)

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MPI_Win_start - Starts an RMA access epoch for win


C Syntax

#include <mpi.h>
int MPI_Win_start(MPI_Group group, int assert, MPI_Win win)

Fortran Syntax

INCLUDE ’mpif.h’

C++ Syntax

#include <mpi.h>
void MPI::Win::Start(const MPI::Group& group, int assert) const

Input Parameters

The group of target processes (handle).
Program assertion (integer).
Window object (handle).

Output Parameters

Fortran only: Error status (integer).


MPI_Win_start is a one-sided MPI communication synchronization call that starts an RMA access epoch for win. RMA calls issued on win during this epoch must access only windows at processes in group. Each process in group must issue a matching call to MPI_Win_post. MPI_Win_start is allowed to block until the corresponding MPI_Win_post calls have been executed, but is not required to.

The assert argument is used to provide assertions on the context of the call that may be used for various optimizations. (See Section 6.4.4 of the MPI-2 Standard.) A value of assert = 0 is always valid. The following assertion value is supported:

When this value is passed in to this call, the library assumes that the post call on the target has been called and it is not necessary for the library to check to see if such a call has been made.


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_Win_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_Win_post MPI_Win_complete

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