readahead

READAHEAD(2)		  Linux Programmer’s Manual		 READAHEAD(2)



NAME
       readahead  - Read in advance one or more pages of a file within a page
       cache

SYNOPSIS
       #include <unistd.h>


       ssize_t sys_readahead (int fd, loff_t offset, size_t count);


DESCRIPTION
       readahead reads count pages in the page cache.  If a page  is  not  in
       the page cache, it is added to the page cache.


       fd is the file descriptor of the file being read.  offset is the loca-
       tion within the file to start reading.  A page in the  page  cache  is
       identified  by  a  file’s inode and by the offset within the file.  fd
       and offset are used to identify the page in the page cache.


       The offset is incremented by one to read the  next  page	 until	count
       pages  are  read.  If count pages is larger than the size of the file,
       then only up to the size of the file is read.


RETURN VALUE
       readahead returns 0 on success; otherwise, it returns the error listed
       in  the "Errors" section.  If the offset specified is greater than the
       size of the file, then nothing is read and 0 is returned.


ERRORS
       EBADF  readahead was not able to get the file.


AUTHOR
       Joy Latten.



Linux 2.4			  2003-02-21			 READAHEAD(2)