Knative performance tests are tests geared towards producing useful performance metrics of the knative system. As such they can choose to take a closed-box point-of-view of the system and use it just like an end-user might see it. They can also go more open-boxy to narrow down the components under test.
Knative uses vegeta to generate HTTP load. It can be configured to generate load at a predefined rate. Officially it supports constant rate and sine rate, but if you want to generate load at a different rate, you can write your own pacer by implementing Pacer interface. Custom pacer implementations used in Knative tests are under pacers.
Knative uses mako for benchmarking. It provides a set of tools for metrics data storage, charting, statistical aggregation and performance regression analysis. To use it to create a benchmark for Knative and run it continuously, please refer to Benchmarks.md.