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NAME
MPI_File_set_atomicity - Sets consistency semantics for data-access
operations (collective).
SYNTAX
C Syntax
#include <mpi.h>
int MPI_File_set_atomicity(MPI_File fh, int flag)
Fortran Syntax
INCLUDE 'mpif.h'
MPI_FILE_SET_ATOMICITY(FH, FLAG, IERROR)
INTEGER FH, FLAG, IERROR
C++ Syntax
#include <mpi.h>
void MPI::File::Set_atomicity(bool flag)
INPUT PARAMETERS
fh File handle (handle).
flag true to enable atomic mode, false to enable nonatomic mode
(boolean).
OUTPUT PARAMETER
IERROR Fortran only: Error status (integer).
DESCRIPTION
The consistency semantics for data-access operations using the set of
file handles created by one collective MPI_File_open is set by collec-
tively calling MPI_File_set_atomicity. All processes in the group must
pass identical values for fh and flag. If flag is true, atomic mode is
set; if flag is false, nonatomic mode is set.
The default value on a call to MPI_File_open in Open MPI is true for
jobs running on more than one node, false for jobs running on a single
SMP. For more information, see the MPI-2 standard.
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++ func-
tions 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. For MPI I/O function errors, the default error handler is set
to MPI_ERRORS_RETURN. The error handler may be changed with
MPI_File_set_errhandler; the predefined error handler
MPI_ERRORS_ARE_FATAL may be used to make I/O errors fatal. Note that
MPI does not guarantee that an MPI program can continue past an error.
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