MPIO_REQUEST man page on IRIX
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mpi_io(3) mpi_io(3)
NAME
mpi_io - Introduction to the ROMIO implementation of MPI I/O routines
DESCRIPTION
MPI I/O routines are based on MPI-2 MPI I/O routines, in which derived
data types are used to express data partitioning. These MPI-2 I/O
routines are derived from the ROMIO 1.2.4 source code. The current IRIX
implementation contains all interfaces defined in the MPI-2 I/O chapter
of the MPI-2 standard except shared file pointer functions (Sec. 9.4.4),
split collective data access functions (Sec. 9.4.5), support for file
interoperability (Sec. 9.5), I/O error handling (Sec. 9.7), and I/O error
classes (Sec. 9.8).
Limitations
The MPI I/O routines have the following limitations:
* Beginning with MPT 1.6, the status argument is set following all
read, write, MPIO_Test, and MPIO_Wait functions. Consequently,
MPI_Get_count and MPI_Get_elements will now work when passed the
status object from these operations. Previously, they did not.
* Beginning with MPT 1.8, all nonblocking I/O functions use the same
MPI_Request object that the message-pass- ing functions use.
Accordingly, you may mix requests from the two classes of functions
in calls to MPI_Wait(), MPI_Test(), and their variants. MPIO_Test()
and MPIO_Wait(), which, prior to MPT 1.8 were required to be used
with requests from nonblock- ing I/O functions only, are no longer
required, but continue to exist for compatibility with older MPT
binary applications.
* All functions return only two possible error codes: MPI_SUCCESS on
success and MPI_ERR_UNKNOWN on failure.
* End-of-file is not detected. The individual file pointer is
increased by the requested amount of data and not by the actual
amount of data read. Therefore, after end-of-file is reached,
MPI_File_get_position(3) returns a wrong offset.
Direct I/O
MPI I/O supports direct access to files stored in XFS filesystems. Direct
access bypasses the system's buffer cache, leading to better performance
in some specialized cases. You can enable direct I/O for read and write
operations by setting the appropriate environment variable(s),
MPIO_DIRECT_READ or MPIO_DIRECT_WRITE, to the string "TRUE," as in the
following example:
setenv MPIO_DIRECT_READ TRUE
setenv MPIO_DIRECT_WRITE TRUE
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mpi_io(3) mpi_io(3)
List of Routines
The MPI I/O routines are as follows:
MPI_File_c2f(3)
MPI_File_close(3)
MPI_File_delete(3)
MPI_File_f2c(3)
MPI_File_get_amode(3)
MPI_File_get_atomicity(3)
MPI_File_get_byte_offset(3)
MPI_File_get_group(3)
MPI_File_get_info(3)
MPI_File_get_position(3)
MPI_File_get_size(3)
MPI_File_get_type_extent(3)
MPI_File_get_view(3)
MPI_File_iread(3)
MPI_File_iread_at(3)
MPI_File_iwrite(3)
MPI_File_iwrite_at(3)
MPI_File_open(3)
MPI_File_preallocate(3)
MPI_File_read(3)
MPI_File_read_all(3)
MPI_File_read_at(3)
MPI_File_read_at_all(3)
MPI_File_seek(3)
MPI_File_set_atomicity(3)
MPI_File_set_info(3)
MPI_File_set_size(3)
MPI_File_set_view(3)
MPI_File_sync(3)
MPI_File_write(3)
MPI_File_write_all(3)
MPI_File_write_at(3)
MPI_File_write_at_all(3)
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