POSIX_FADVISE(P) POSIX Programmer's Manual POSIX_FADVISE(P)
posix_fadvise - file advisory information (ADVANCED REALTIME)
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:
Specifies that the application has no advice to give on its behavior with respect to the specified data. It is the default charac-
teristic if no advice is given for an open file.
Specifies that the application expects to access the specified data sequentially from lower offsets to higher offsets.
Specifies that the application expects to access the specified data in a random order.
Specifies that the application expects to access the specified data in the near future.
Specifies that the application expects that it will not access the specified data in the near future.
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.
The posix_fadvise() function is part of the Advisory Information option and need not be provided on all implementations.
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 Technol-
ogy -- 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 .
IEEE/The Open Group 2003 POSIX_FADVISE(P)