HP-UX Reference (11i v3 07/02) - 2 System Calls (vol 5)

p
posix_fadvise(2) posix_fadvise(2)
NAME
posix_fadvise(), posix_fadvise64() - file advisory information
SYNOPSIS
#include <sys/fcntl.h>
int posix_fadvise(
int
fd,
off_t
offset,
off_t
len,
int
advice
);
int posix_fadvise64(
int
fd,
off_t
offset,
off_t
len,
int
advice
);
Parameters
fd The open file descriptor to which the fadvise operation applies.
offset The begining of the specified range as a positive, byte offset.
len The length of the specified range in bytes.
advice Specifies advice to be applied to range.
DESCRIPTION
The posix_fadvise()
function is used to advise the system about the expected behavior of the applica-
tion 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 fol-
lowing offset is specified.
It should be noted that the effect of all hints is cumulative for a given file object. All hints will be removed
on processing the last close of the file object.
The
posix_fadvise64()
function may be used for large file access by a 32-bit application built with
_FILE_OFFSET_BITS
set to 64.
The advice parameter is used to convey the hint to be applied to the data 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 range of data
sequentially from the lower offsets to higher offsets.
POSIX_FADV_RANDOM Specifies that the application will expect to access the specified specified
range of data in a random order.
POSIX_FADV_WILLNEED Specifies that the application will expect to access the specified range of
data in the near future.
POSIX_FADV_DONTNEED Specifies that the application will expect that it will not access the
specified range of data in the near future.
POSIX_FADV_NOREUSE Specifies that the application will expect to access the specified range of
data once and then not reuse it thereafter.
These values will be defined in <sys/fcntl.h>.
RETURN VALUE
0 Successful completion.
-1 Failure. errno is set to indicate the error.
270 Hewlett-Packard Company − 1 − HP-UX 11i Version 3: February 2007