CPU Load Generator

This script generates a fixed CPU load for a finite or indefinite time period, on one or more CPU cores. A PI controller is used for this purpose.

You provide the desired CPU load and the CPU core(s) to load. The controller and the CPU monitor run in separate threads.

Supported platforms: Linux, macOS, and Windows (Windows is less tested; psutil supports CPU affinity on all three).

Theoretical insight

• Project homepage: https://gaetanocarlucci.github.io/CPULoadGenerator/ — more details on the tool.
• Blog: Theoretical explanation of this tool.

Dependencies

• Python 3.9+ (tested with 3.13)

Setup (Linux and macOS)

Create and activate a virtual environment, then install dependencies:

cd CPULoadGenerator/
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

Run the script (e.g. 20% load on core 0 for 10 seconds):

python cpu_load_generator.py -l 0.2 -d 10 -c 0

Or make the script executable and run: chmod +x cpu_load_generator.py then ./cpu_load_generator.py -l 0.2 -d 10 -c 0.

System-wide install (Debian/Ubuntu): sudo apt install python3-matplotlib python3-psutil python3-click

Platform notes: On macOS, CPU affinity is not supported, so the load may be distributed across cores. Use exactly one core with --plot for the live plot window and PNG (e.g. -c 0 -l 0.5 -d 20 --plot); with multiple cores, --plot is ignored.

Docker

Run from Docker Hub:

docker run --rm gaetano/cpuloadgen -c 0 -l 0.2 -d 10

Build locally: docker build -t cpuloadgen .

Examples

1. 20% load on core 0 for 20 seconds:

   ./cpu_load_generator.py -l 0.2 -d 20 -c 0

2. 65% load on cores 0, 1 and 5, until interrupted (Ctrl-C):

   ./cpu_load_generator.py -l 0.65 -c 0 -c 1 -c 5

3. 55% load on core 0, 12% on core 3, until interrupted:

   ./cpu_load_generator.py -c 0 -c 3 -l 0.55 -l 0.12

4. 12% load on cores 0 and 1 for 20.5 seconds, then plot the load:

   ./cpu_load_generator.py -l 0.12 -c 0 -c 1 -d 20.5 --plot

5. Example graph of CPU load (50% target on core 0):

   

Tests

Test and identification scripts live in tests/ (see tests/README.md). Expected output from the PID script after CPU identification: