MPI_File_get_info(3OpenMPI)											       MPI_File_get_info(3OpenMPI)

NAME

       MPI_File_get_info - Returns a new info object containing values for current hints associated with a file.

SYNTAX

       C Syntax
	   #include <mpi.h>
	   int MPI_File_get_info(MPI_File fh, MPI_Info *info_used)

       Fortran Syntax
	   INCLUDE 'mpif.h'
	   MPI_FILE_GET_INFO(FH, INFO_USED, IERROR)
		  INTEGER    FH, INFO_USED, IERROR

C++ Syntax
       #include <mpi.h>
       MPI::Info MPI::File::Get_info() const

INPUT PARAMETER

       fh	 File handle (handle).

OUTPUT PARAMETERS

       info_used New info object (handle).

       IERROR	 Fortran only: Error status (integer).

DESCRIPTION

       MPI_File_get_info  returns  a  new  info object containing all the hints that the system currently associates with the file fh. The current
       setting of all hints actually used by the system related to this open file is returned in info_used. The user is  responsible  for  freeing
       info_used via MPI_Info_free.

       Note  that  the	set  of  hints	returned  in  info_used  may  be  greater  or  smaller	than  the set of hints passed in to MPI_File_open,
       MPI_File_set_view, and MPI_File_set_info, as the system may not recognize some hints set by the user, and may automatically set other hints
       that the user has not requested to be set. 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_used 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 exit-
       ing 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++ 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.

Open MPI 1.2							  September 2006				       MPI_File_get_info(3OpenMPI)