It is now possible from kernel version 2.6.16 to drop Linux internal caches (page caches, inodes and dentry caches). This can be done by echoing a number into
/proc/sys/vm/drop_caches :
To drop page cache :
echo 1 > /proc/sys/vm/drop_caches
To drop inode and dentry cache :
echo 2 > /proc/sys/vm/drop_caches
And finally to drop everything :
echo 3 > /proc/sys/vm/drop_caches
Source :
Drop Caches - linux-mm.org
