# check for swap space
swapon -s

# check filesystem
df -h

# create and enabled the swap file (e.g. 512MB)
sudo dd if=/dev/zero of=/swapfile bs=1024 count=512k
sudo mkswap /swapfile

# activate the swap file
sudo swapon /swapfile

# add swap to filesystem
vi /etc/fstab
# by pasting the following
/swapfile swap swap defaults 0 0

# set ownership and permission
chown root:root /swapfile
chmod 600 /swapfile

# configure swappiness (0-100, 100 = swap often and too soon usually)
sysctl vm.swappiness=10
cat /proc/sys/vm/swappiness

# (optional) set swappiness on boot
vi /etc/sysctl.conf
# and set
vm.swappiness=10
# note: It may be useful to set your swappiness to 0 to ensure that your VPS operates optimally.