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 appropri-
       ate read-ahead and caching techniques for access to the corresponding file. This is similar to the POSIX version  of  the
       madvise  system  call,  but for file access instead of memory access. The sys_fadvise64() function is obsolete and corre-
       sponds to a broken glibc API, sys_fadvise64_64() is the fixed version.  The following are the values for the  advice  pa-
       rameter:


       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  map-
              pings without an underlying 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 modules.


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


SEE ALSO
       madvise(2)



AUTHOR
       Niki Rahimi



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