Keep CPU busy with a Systemd service

In order to test/burn-in your server, we need to keep the processor utilization at a specific percentage for a long period of time. Running a solo script to keep the system busy can lead to termination of the script randomly and thus failure of the job.

Here, we’ll create a bash script that keeps the processor busy at a specific percentage and run the script as a service which restarts whenever the service fails. This ensures that your processor will always be utilized at the given percentage, so you can test/burn-in or keep your server busy so that cloud providers do not reclaim it 🙂

Stress-ng is an amazing library which can be used to stress a number of components of a server, and is used to here keep the processor busy. If you don’t have it, you can install it using:

sudo apt install stress-ng

Here are the steps:

Create a bash script with the following code and save it as busy.sh:
```
#!/bin/bash
stress-ng --cpu 0 --cpu-load 30 -t 0
```
You can edit the --cpu-load to keep your desired CPU load percentage. We’re going with 30% here.
Make the bash script executable by running the following command on your terminal:
```
chmod +x busy.sh
```

Create a new service in Systemd in this directory /etc/systemd/system:

[Unit]
Description=keep CPU busy
[Service]
Type=simple
User=root
Group=root
ExecStart=/home/ubuntu/busy.sh #path to the created busy.sh
Restart=on-failure
RestartSec=5
[Install]
WantedBy=multi-user.target

Reload the service files to include the newly created service:
```
sudo systemctl daemon-reload
```
Start your keep-busy service:
```
sudo systemctl start busy.service
```
Check the status of your service:
```
sudo systemctl status busy.service
```
To start your service on every reboot:
```
sudo systemctl enable busy.service
```
To stop your service:
```
sudo systemctl stop busy.service
```
To disable starting of the service on every reboot:
```
sudo systemctl disable busy.service
```

You can use htop command to check if stress-ng is running at the specified CPU percentage utilization.

something

Enjoy keeping busy and don’t let cloud providers claim your server.

Best,
Pastav