Controlling CPU usage
You can control resource usage either by using the systemctl set-property command or by editing systemd unit files. For the first demo, we'll have Vicky put some stress on the virtual machine's CPUs. We'll deal with it by using systemctl set-property to configure the cpu resource controller.
Controlling Vicky's CPU usage
By default, all users on a Linux system have unlimited use of the system resources. That could be problematic on a system with multiple users. Any user could decide to hog all the resources, which could effectively cause a Denial-of-Service situation for all the other users. In real life, a user could cause trouble by doing something completely innocent, such as rendering a large video file. An authorized user could also cause a Denial-of-Service by doing something they aren't supposed to do, such as using server resources to do some cryptocurrency mining. In any case, we want to limit the resources that a user can...