MPIFilesetinfo(3OpenMPI) MPIFilesetinfo(3OpenMPI)

NAME
       MMPPIIFFiilleesseettiinnffoo - Sets new values for hints (collective).


SSYYNNTTAAXX
       C Syntax
           #include 
           int MPIFilesetinfo(MPIFile fh, MPIInfo info)

       Fortran Syntax
           INCLUDE 'mpif.h'
           MPIFILESETINFO(FH, INFO, IERROR)
                  INTEGER    FH, INFO, IERROR


CC++++ SSyynnttaaxx
       #include 
       void MPI::File::Setinfo(const MPI::Info& info)


IINNPPUUTT//OOUUTTPPUUTT PPAARRAAMMEETTEERR
       fh        File handle (handle).


IINNPPUUTT PPAARRAAMMEETTEERR
       info      Info object (handle).


OOUUTTPPUUTT PPAARRAAMMEETTEERR
       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       MPIFilesetinfo  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 MPIFileopen, MPIFiledelete, MPIFilesetview, and
       MPIFilesetinfo 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  pro-
       cesses:  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.


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

       SETTABLE HINTS:

       -  sharedfiletimeout:  Amount of time (in seconds) to wait for access
       to the shared file pointer before exiting with MPIERRTIMEDOUT.

       - rwlocktimeout: 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 MPIERRTIMEDOUT.

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

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

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

       - collwritebufsize:  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.

       -  mpiioconcurrency:  (boolean)  controls whether nonblocking I/O rou-
       tines can bind an extra thread to an LWP.

       - mpiiocollcontiguous: (boolean) controls whether subsequent  collec-
       tive  data accesses will request collectively contiguous regions of the
       file.

       NON-SETTABLE HINTS:

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


EERRRROORRSS
       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::ERRORSTHROWEXCEPTIONS, 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  MPIERRORSRETURN.  The  error  handler   may   be   changed   with
       MPIFileseterrhandler;      the      predefined     error     handler
       MPIERRORSAREFATAL 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     MPIFilesetinfo(3OpenMPI)