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SYNTAX
C Syntax
#include <mpi.h>
int MPI_File_set_view(MPI_File fh, MPI_Offset disp,
MPI_Datatype etype, MPI_Datatype filetype,
const char *datarep, MPI_Info info)
Fortran Syntax
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_SET_VIEW(FH, DISP, ETYPE,
FILETYPE, DATAREP, INFO, IERROR)
INTEGER FH, ETYPE, FILETYPE, INFO, IERROR
CHARACTER*(*) DATAREP
INTEGER(KIND=MPI_OFFSET_KIND) DISP
Fortran 2008 Syntax
USE mpi_f08
MPI_File_set_view(fh, disp, etype, filetype, datarep, info, ierror)
TYPE(MPI_File), INTENT(IN) :: fh
INTEGER(KIND=MPI_OFFSET_KIND), INTENT(IN) :: disp
TYPE(MPI_Datatype), INTENT(IN) :: etype, filetype
CHARACTER(LEN=*), INTENT(IN) :: datarep
TYPE(MPI_Info), INTENT(IN) :: info
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
INPUT/OUTPUT PARAMETER
• fh: File handle (handle).
INPUT PARAMETERS
• disp: Displacement (integer).
• etype: Elementary data type (handle).
• filetype: File type (handle). See Restrictions, below.
• datarep: Data representation (string).
• info: Info object (handle).
OUTPUT PARAMETER
• ierror: Fortran only: Error status (integer).
DESCRIPTION
The MPI_File_set_view 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, MPI_File_set_view resets the
independent file pointers and the shared file pointer to zero. MPI_File_set_view is collective across the
fh; all processes in the group must pass identical values for datarep and provide an etype with an
identical extent. The 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 filetype 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 MPI_File_set_view interface allows the user to pass a data-representation string to MPI I/O via the
datarep argument. To obtain the default value pass the value “native”. The user can also pass information
via the info argument. 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
• MPI_INFO_NULL
• 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-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 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 MPI man page for a full list of MPI error codes.
See the Error Handling section of the MPI-3.1 standard for more information.
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2003-2025, The Open MPI Community
Feb 17, 2025 MPI_FILE_SET_VIEW(3)