Clear Linux Memory Buffer Cache:

• Free pagecache, dentries and inodes in cache memory # sync; echo 3 > /proc/sys/vm/drop_caches.
• Free dentries and inodes use following command # sync; echo 2 > /proc/sys/vm/drop_caches.
• Free pagecache only use following command # sync; echo 1 > /proc/sys/vm/drop_caches.

-- vladget