1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
.. _mpi_file_get_info:
MPI_File_get_info
=================
.. include_body
:ref:`MPI_File_get_info` |mdash| Returns a new info object containing values for
current hints associated with a file.
SYNTAX
------
C Syntax
^^^^^^^^
.. code-block:: c
#include <mpi.h>
int MPI_File_get_info(MPI_File fh, MPI_Info *info_used)
Fortran Syntax
^^^^^^^^^^^^^^
.. code-block:: fortran
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_GET_INFO(FH, INFO_USED, IERROR)
INTEGER FH, INFO_USED, IERROR
Fortran 2008 Syntax
^^^^^^^^^^^^^^^^^^^
.. code-block:: fortran
USE mpi_f08
MPI_File_get_info(fh, info_used, ierror)
TYPE(MPI_File), INTENT(IN) :: fh
TYPE(MPI_Info), INTENT(OUT) :: info_used
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
INPUT PARAMETER
---------------
* ``fh``: File handle (handle).
OUTPUT PARAMETERS
-----------------
* ``info_used``: New info object (handle).
* ``ierror``: Fortran only: Error status (integer).
DESCRIPTION
-----------
:ref:`MPI_File_get_info` returns a new info object containing all the hints
that the system currently associates with the file *fh*. The current
setting of all hints actually used by the system related to this open
file is returned in *info_used*. The user is responsible for freeing
*info_used* via :ref:`MPI_Info_free`.
Note that the set of hints returned in *info_used* may be greater or
smaller than the set of hints passed in to :ref:`MPI_File_open`,
:ref:`MPI_File_set_view`, and :ref:`MPI_File_set_info`, as the system
may not recognize some hints set by the user, and may automatically
set other hints that the user has not requested to be set. See the
:ref:`HINTS section <man-openmpi-mpi-file-get-info>` for a list of
hints that can be set.
.. _man-openmpi-mpi-file-get-info:
HINTS
-----
The following hints can be used as values for the *info_used* 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.
.. 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
------
.. include:: ./ERRORS.rst
|
