Originální popis anglicky:
posix_fadvise - file advisory information (
ADVANCED REALTIME)
Návod, kniha: POSIX Programmer's Manual
#include <fcntl.h>
int posix_fadvise(int
fd, off_t
offset , size_t len,
int advice);
The
posix_fadvise() function shall advise the implementation on the
expected behavior of the application with respect to the data in the file
associated with the open file descriptor,
fd, starting at
offset
and continuing for
len bytes. The specified range need not currently
exist in the file. If
len is zero, all data following
offset is
specified. The implementation may use this information to optimize handling of
the specified data. The
posix_fadvise() function shall have no effect
on the semantics of other operations on the specified data, although it may
affect the performance of other operations.
The advice to be applied to the data is specified by the
advice parameter
and may be one of the following values:
- POSIX_FADV_NORMAL
-
Specifies that the application has no advice to give on its behavior with
respect to the specified data. It is the default characteristic if no
advice is given for an open file.
- POSIX_FADV_SEQUENTIAL
-
Specifies that the application expects to access the specified data
sequentially from lower offsets to higher offsets.
- POSIX_FADV_RANDOM
-
Specifies that the application expects to access the specified data in a
random order.
- POSIX_FADV_WILLNEED
-
Specifies that the application expects to access the specified data in the
near future.
- POSIX_FADV_DONTNEED
-
Specifies that the application expects that it will not access the specified
data in the near future.
- POSIX_FADV_NOREUSE
-
Specifies that the application expects to access the specified data once and
then not reuse it thereafter.
These values are defined in
<fcntl.h>.
Upon successful completion,
posix_fadvise() shall return zero; otherwise,
an error number shall be returned to indicate the error.
The
posix_fadvise() function shall fail if:
- EBADF
- The fd argument is not a valid file descriptor.
- EINVAL
- The value of advice is invalid.
- ESPIPE
- The fd argument is associated with a pipe or FIFO.
The following sections are informative.
None.
The
posix_fadvise() function is part of the Advisory Information option
and need not be provided on all implementations.
None.
None.
posix_madvise() , the Base Definitions volume of
IEEE Std 1003.1-2001,
<fcntl.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
