How to Check Memory ?

1) watch -n 3 cat /proc/meminfo
2) watch -n 3 free -m

How to free Memory ?

1. Freeing Up the Page Cache
echo 1 > /proc/sys/vm/drop_caches
2. Freeing Up the Dentries and Inodes
echo 2 > /proc/sys/vm/drop_caches
3. Freeing Up the Page Cache, Dentries and Inodes
echo 3 > /proc/sys/vm/drop_caches
4. Flushing the File System Buffers