Free Clear Purge System memory ( RAM ) in Linux.
Its best to leave the memory management to linus kernel but if you must clear up some memory then this is how you do it.
Execute this command as root:
sync; echo 3 > /proc/sys/vm/drop_caches
What does it do ?
sync; will write all the unwritten data to disk so that nothing is lost.
echo 3 > /proc/sys/vm/drop_caches; will drop all the cached data from memory.