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MPI_File_set_info

:ref:`MPI_File_set_info` - Sets new values for hints (collective).

SYNTAX

C Syntax

#include <mpi.h>

int MPI_File_set_info(MPI_File fh, MPI_Info info)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_SET_INFO(FH, INFO, IERROR)
     INTEGER FH, INFO, IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_File_set_info(fh, info, ierror)
     TYPE(MPI_File), INTENT(IN) :: fh
     TYPE(MPI_Info), INTENT(IN) :: info
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT/OUTPUT PARAMETER

  • fh: File handle (handle).

INPUT PARAMETER

  • info: Info object (handle).

OUTPUT PARAMETER

  • ierror: Fortran only: Error status (integer).

DESCRIPTION

:ref:`MPI_File_set_info` is a collective routine that sets new values for the hints of the file associated with fh. These hints are set for each file, using the :ref:`MPI_File_open`, :ref:`MPI_File_delete`, :ref:`MPI_File_set_view`, and :ref:`MPI_File_set_info` routines. The opaque info object, which allows you to provide hints for optimization of your code, may be different on each process, but some info entries are required to be the same on all processes: In these cases, they must appear with the same value in each process's info object. See the :ref:`HINTS section <man-openmpi-mpi-file-set-info>` for a list of hints that can be set.

HINTS

The following hints can be used as values for the info argument.

SETTABLE HINTS

  • shared_file_timeout: Amount of time (in seconds) to wait for access to the shared file pointer before exiting with MPI_ERR_TIMEDOUT.

  • rwlock_timeout: Amount of time (in seconds) to wait for obtaining a read or write lock on a contiguous chunk of a UNIX file before exiting with MPI_ERR_TIMEDOUT.

  • noncoll_read_bufsize: Maximum size of the buffer used by MPI I/O to satisfy read requests in the noncollective data-access routines.

    Note

    A buffer size smaller than the distance (in bytes) in a UNIX file between the first byte and the last byte of the access request causes MPI I/O to iterate and perform multiple UNIX read() or write() calls. If the request includes multiple noncontiguous chunks of data, and the buffer size is greater than the size of those chunks, then the UNIX read() or write() (made at the MPI I/O level) will access data not requested by this process in order to reduce the total number of write() calls made. If this is not desirable behavior, you should reduce this buffer size to equal the size of the contiguous chunks within the aggregate request.

  • noncoll_write_bufsize: Maximum size of the buffer used by MPI I/O to satisfy write requests in the noncollective data-access routines.

    See the above note in noncoll_read_bufsize.

  • coll_read_bufsize: Maximum size of the buffer used by MPI I/O to satisfy read requests in the collective data-access routines.

    See the above note in noncoll_read_bufsize.

  • coll_write_bufsize: Maximum size of the buffer used by MPI I/O to satisfy write requests in the collective data-access routines.

    See the above note in noncoll_read_bufsize.

  • mpiio_concurrency: (boolean) controls whether nonblocking I/O routines can bind an extra thread to an LWP.

  • mpiio_coll_contiguous: (boolean) controls whether subsequent collective data accesses will request collectively contiguous regions of the file.

    NON-SETTABLE HINTS

  • filename: Access this hint to get the name of the file.

ERRORS