MPIFilesetview(3OpenMPI) MPIFilesetview(3OpenMPI)

NAME
       MMPPIIFFiilleesseettvviieeww  -  Changes  process's  view of data in file (collec-
       tive).

SSYYNNTTAAXX
       C Syntax
           #include 
           int MPIFilesetview(MPIFile fh, MPIOffset disp,
                  MPIDatatype etype, MPIDatatype filetype,
                  char *datarep, MPIInfo info)

       Fortran Syntax (see FORTRAN 77 NOTES)
           INCLUDE 'mpif.h'
           MPIFILESETVIEW(FH, DISP, ETYPE,
                   FILETYPE, DATAREP, INFO, IERROR)
             INTEGER FH, ETYPE, FILETYPE, INFO, IERROR
             CHARACTER*(*) DATAREP
             INTEGER(KIND=MPIOFFSETKIND) DISP


CC++++ SSyynnttaaxx
       #include 
       void MPI::File::Setview(MPI::Offset disp,
            const MPI::Datatype& etype,
            const MPI::Datatype& filetype, const char* datarep,
            const MPI::Info& info)


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


IINNPPUUTT PPAARRAAMMEETTEERRSS
       disp      Displacement (integer).

       etype     Elementary data type (handle).

       filetype  File type (handle). See Restrictions, below.

       datarep   Data representation (string).

       info      Info object (handle).


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


DESCRIPTION
       The MPIFilesetview routine changes the process's view of the data in
       the  file  -  the beginning of the data accessible in the file through
       that view is set to disp; the type of data is set  to  etype;  and  the
       distribution  of  data  to  processes is set to filetype.  In addition,
       MPIFilesetview resets the independent file pointers and  the  shared
       file pointer to zero. MPIFilesetview is collective; all processes in
       the group must pass identical values for fh and etype; values for disp,
       filetype,  and  info  may  vary. It is erroneous to use the shared file
       pointer data-access routines unless identical values for disp and file-
       type  are  also given. The data types passed in etype and filetype must
       be committed.

       The disp displacement argument specifies the position (absolute  offset
       in bytes from the beginning of the file) where the view begins.

       The  MPIFilesetview  interface allows the user to pass a data-repre-
       sentation string to MPI I/O via the datarep  argument.  To  obtain  the
       default value (or "native"), pass NULL. The user can also pass informa-
       tion via the info argument. See the HINTS section for a list  of  hints
       that can be set. For more information, see the MPI-2 standard.


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

       SETTABLE HINTS:

       - MPIINFONULL

       -  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.


FFOORRTTRRAANN 7777 NNOOTTEESS
       The MPI standard prescribes portable Fortran syntax for the DISP  argu-
       ment  only  for  Fortran 90.  FORTRAN 77 users may use the non-portable
       syntax

            INTEGER*MPIOFFSETKIND DISP

       where MPIOFFSETKIND is a constant defined in  mpif.h  and  gives  the
       length of the declared integer in bytes.


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     MPIFilesetview(3OpenMPI)