====== Linux - drop cache ======

  * Clear PageCache only:
<code>
# sync; echo 1 > /proc/sys/vm/drop_caches
</code>
  * Clear dentries and inodes:
<code>
# sync; echo 2 > /proc/sys/vm/drop_caches
</code>
  * Clear PageCache, dentries and inodes:
<code>
# sync; echo 3 > /proc/sys/vm/drop_caches
</code>