|
« Return to documentation listing
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 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.
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.)
- 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 rou-
tines can bind an extra thread to an LWP.
- mpiio_coll_contiguous: (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.
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.
1.3.4 Nov 11, 2009 MPI_File_set_info(3)
« Return to documentation listing
|
