posix_fadvise(2) [netbsd man page]

POSIX_FADVISE(2)					      BSD System Calls Manual						  POSIX_FADVISE(2)

NAME

     posix_fadvise -- hint at the future access pattern of a file

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/fcntl.h>

     int
     posix_fadvise(int fd, off_t offset, off_t size, int hint);

DESCRIPTION

     posix_fadvise() hints at the application's access pattern to the file and range given by the file descriptor, fd, and offset and size.  If
     size is zero, it means to the end of file.

     hint should be one of the followings.

	   POSIX_FADV_NORMAL	  No hint.  (default)
	   POSIX_FADV_RANDOM	  Random access.
	   POSIX_FADV_SEQUENTIAL  Sequential access.  (from lower offset to higher offset.)
	   POSIX_FADV_WILLNEED	  Will be accessed.
	   POSIX_FADV_DONTNEED	  Will not be accessed.
	   POSIX_FADV_NOREUSE	  Will be accessed just once.

     Calling posix_fadvise() doesn't alter the semantics of the operations, it is only a matter of performance.

RETURN VALUES

     On success, posix_fadvise() returns 0.  Otherwise, it returns an error number.

SEE ALSO

     errno(2), madvise(2)

BUGS

     For POSIX_FADV_NORMAL, POSIX_FADV_RANDOM, and POSIX_FADV_SEQUENTIAL, the current implementation ignores offset and size, and applies the hint
     to the whole file.

BSD
								   June 9, 2009 							       BSD

posix_fadvise(3C)					   Standard C Library Functions 					 posix_fadvise(3C)

NAME

       posix_fadvise - file advisory information

SYNOPSIS

       #include <fcntl.h>

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

DESCRIPTION

       The posix_fadvise() function advises the system 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 system may use this information to optimize handling of the specified
       data. The posix_fadvise() function has 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 off-
				sets.

       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 VALUES

       Upon successful completion, posix_fadvise() returns zero. Otherwise, an error number is returned to indicate the error.

ERRORS

       The posix_fadvise() function will fail if:

       EBADF	 The fd argument is not a valid file descriptor.

       EINVAL	 The value of advice is invalid, or the value of len is less than zero.

       ESPIPE	 The fd argument is associated with a pipe or FIFO.

USAGE

       The posix_fadvise() function has a transitional interface for 64-bit file offsets. See lf64(5).

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+
       |Standard		     |See standards(5). 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       posix_madvise(3C), attributes(5), standards(5)

SunOS 5.11							    14 Jul 2008 						 posix_fadvise(3C)