C Syntax

       2003-2025, The Open MPI Community

                                                  Jun 07, 2025                              MPI_FILE_SET_INFO(3)

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 MPI_File_open, MPI_File_delete,  MPI_File_set_view,  and
       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
       HINTSsection for a list of hints that can be set.

       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 MPImanpage for a full list of MPIerrorcodes.

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

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

       SETTABLEHINTS

       • 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-SETTABLEHINTS

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

       • info: Info object (handle).

       • fh: File handle (handle).

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

CSyntax
          #include <mpi.h>

          int MPI_File_set_info(MPI_File fh, MPI_Info info)

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

   Fortran2008Syntax
          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