fadvise64_64

FADVISE64,FADVISE64_64(2)  Linux Programmer’s Guide FADVISE64,FADVISE64_64(2)



NAME
       fadvise64,fadvise64_64 - Give advice about file access

SYNOPSIS
       long fadvise64_64 (int fs, loff_t offset, loff_t len, int advice,
						   int fs, loff_t offset,
						   loff_t len, int advice);

       long sys_fadvise64  (int fs, loff_t offset, loff_t len, int advice,
			  int fs, loff_t offset, loff_t len, int advice);


DESCRIPTION
       Allows an application to to tell the kernel how it expects  to  use  a
       file  handle, so that the kernel can choose appropriate read-ahead and
       caching techniques for access to the corresponding file. This is simi-
       lar  to the POSIX version of the madvise system call, but for file ac-
       cess instead of memory access. The sys_fadvise64() function  is	obso-
       lete  and corresponds to a broken glibc API, sys_fadvise64_64() is the
       fixed version.  The following are the values for the advice parameter:


       FADV_NORMAL
	      No special treatment.


       FADV_RANDOM
	      Expect page references in random order.


       FADV_SEQUENTIAL
	      Expect page references in sequential order.


       FADV_WILLNEED
	      Expect access in the near future.


       FADV_DONTNEED
	      Do  not  expect access in the near future. Subsequent access of
	      pages in this range will succeed, but  will  result  either  in
	      reloading	 of  the  memory  contents from the underlying mapped
	      file or zero-fill-in-demand pages for mappings without  an  un-
	      derlying file.


       FADV_NOREUSE
	      Access data only once.


RETURN VALUE
       delete_module  returns  0 on success; otherwise, it returns one of the
       errors listed in the "Errors" section.


ERRORS
       -EBADF An invalid file descriptor was specified. to  modify  the	 mod-
	      ules.


       -EINVAL
	      An  invalid  f_mapping of file, len value smaller than 0 or ad-
	      vice value unknown.


SEE ALSO
       madvise(2)




AUTHOR
       Niki Rahimi



Linux 2.6			2004-March-12	    FADVISE64,FADVISE64_64(2)