root@tokyo:~# apt-get install -y dphys-swapfile

After that /etc/dphys-swapfile needs to be edited:

root@tokyo:~# vi /etc/dphys-swapfile

Here you can make various settings but for now let’s just use double the size of the RAM for the SWAP that should be created by changing

#CONF_SWAPFACTOR=2

to

CONF_SWAPFACTOR=2

Close and save /etc/dphys-swapfile and restart dphys-swapfile.

root@tokyo:~# /etc/init.d/dphys-swapfile restart

If you run

root@tokyo:~# top

you now can see your SWAP.