POSIX_FADVISE(P)					     POSIX Programmer's Manual						  POSIX_FADVISE(P)

NAME

       posix_fadvise - file advisory information (ADVANCED REALTIME)

SYNOPSIS

       #include <fcntl.h>

       int posix_fadvise(int fd, off_t offset, size_t len, int advice);

DESCRIPTION

       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 charac-
	      teristic 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>.

RETURN VALUE

       Upon successful completion, posix_fadvise() shall return zero; otherwise, an error number shall be returned to indicate the error.

ERRORS

       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.

EXAMPLES

       None.

APPLICATION USAGE

       The posix_fadvise() function is part of the Advisory Information option and need not be provided on all implementations.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       posix_madvise() , the Base Definitions volume of IEEE Std 1003.1-2001, <fcntl.h>

COPYRIGHT

       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)