POSIX_FADVISE(3P) POSIX Programmer's Manual POSIX_FADVISE(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of
this interface may differ (consult the corresponding Linux manual page for details of
Linux behavior), or the interface may not be implemented on Linux.
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 characteristic 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
Specifies that the application expects to access the specified data in the near
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 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 orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 POSIX_FADVISE(3P)