fop - call posix_fadvise on files

Usage: fop [-a|--advice <advice|#>] [-d|--dump] [-s|--sync]
           [-v|--verbose] [-L|--links] [-R|--recursive]
           <file> ..

  -d is equivalent to -a POSIX_FADV_DONTNEED.
  See posix_fadvise(2) for advice names and numbers.

This tool can be used to drop files from the OS's buffer cache, which
allows you do perform reliable benchmarks using data read from
disk. It is a more surgical alternative to Linux's:

  echo 3 > /proc/sys/vm/drop_caches

Typical usage is:

  fop -dR <directory_to_dump>