What is the "% CPU usage" pin?

I see this pin on the output of the targetInterface block. How does it work?

This pin shows what percent

This pin shows what percent of your sample interval is used by your algorithm. For example, if you sample at 1kHz, you will have a sample interval of 1 ms. If your algorithm takes 250 microsecs to run, the output from the pin will be 25, indicating that you are using 25% of your 1 ms sample interval. If you speed up your sample rate to 2 kHz, you should see your usage go up to 50%.