NAME

       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

           INCLUDE 'mpif.h'
           MPI_FILE_SET_INFO(FH, INFO, IERROR)
                  INTEGER    FH, INFO, IERROR

C++ Syntax

       #include <mpi.h>
       void MPI::File::Set_info(const MPI::Info& info)

INPUT/OUTPUT PARAMETER

       fh        File handle (handle).

INPUT PARAMETER

       info      Info object (handle).

OUTPUT PARAMETER

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       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
       HINTS section 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. (See NOTE, below.)

       - noncoll_write_bufsize: Maximum size of the buffer used  by  MPI  I/O  to  satisfy  write
       requests in the noncollective data-access routines. (See NOTE, below.)

       -  coll_read_bufsize:  Maximum size of the buffer used by MPI I/O to satisfy read requests
       in the collective data-access routines. (See NOTE, below.)

       - coll_write_bufsize:  Maximum size of the  buffer  used  by  MPI  I/O  to  satisfy  write
       requests in the collective data-access routines. (See NOTE, below.)

       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.

       - 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

       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. 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.