sudo dd if=/dev/zero of=/swapfile count=4096 bs=1MiB
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
sudo swapon -s
Ref :
https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-centos-7
https://unix.stackexchange.com/questions/294600/i-cant-enable-swap-space-on-centos-7
