Add swap space on a Linux VPS

Check current swap:

sudo swapon --show
free -h

Create a 10GB swap file:

sudo fallocate -l 10G /swapfile
sudo chmod 0600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile

To limit RAM usage to 80%:

grep MemTotal /proc/meminfo
# calculate: result = value * 1024 * 0.8
ulimit -m {result}

Make it permanent by adding to /etc/fstab:

/swapfile none swap sw 0 0