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Stress Testing

pitop includes a built-in CPU stress test for benchmarking and thermal testing your Raspberry Pi.

Starting a stress test

From the command line

# Start with stress test enabled (uses all CPU cores)
pitop --stress

# Start with a specific number of worker threads
pitop --stress --stress-workers 2

At runtime

If pitop was launched with --stress, you can toggle the stress test on and off:

Key Action
Ctrl+S Toggle stress test on/off
Ctrl+Up Add one worker thread
Ctrl+Down Remove one worker thread

Note

The stress test controls (Ctrl+S, Ctrl+Up/Down) are only available when pitop was launched with the --stress flag. Without it, these key bindings have no effect.

How it works

The stress test spawns CPU-intensive worker threads that perform prime number computation via trial division. Each worker runs in a tokio::task::spawn_blocking task with its own atomic stop flag, so workers can be individually started and stopped without affecting the rest of the application.

Worker count

  • Default: one worker per CPU core (detected from /proc/cpuinfo)
  • Minimum: 1 worker
  • Maximum: 2x the initial worker count

For example, on a Pi 5 with 4 cores, the default is 4 workers with a maximum of 8.

Monitoring under stress

The stress test is designed to be used alongside pitop's monitoring features:

  • Overview tab -- watch CPU gauges hit 100% across all cores
  • Overview tab -- watch temperature climb in real-time via the sparkline
  • Power tab -- monitor power draw increase on Pi 5 PMIC rails
  • Header bar -- check for throttle events (under-voltage, thermal throttling)

This makes it easy to test:

  • Thermal performance -- does your cooling solution keep temperatures safe?
  • Power supply adequacy -- does the Pi throttle due to under-voltage under load?
  • System stability -- does the system remain responsive under full load?

When a stress test is active, the footer bar shows the stress test status:

[STRESS 4/8 workers 02:30]

This shows:

  • Current worker count / maximum workers
  • Elapsed time since the stress test started

The indicator is color-coded:

Color Meaning
Green Fewer workers than the initial count
Yellow Workers equal to the initial count
Red More workers than the initial count

When the stress test is stopped, the footer shows [STRESS STOPPED].

Stopping the stress test

Press Ctrl+S to stop all workers. Workers are signaled to stop via atomic flags and terminate within a few milliseconds. The CPU load should drop almost immediately.

Closing pitop (via q or Ctrl+C) also stops all stress test workers automatically.