Measuring the performance of asynchronous systems with PAFAS

Based on Process Algebra for Faster Asynchronous Systems (PAFAS), a testing-based faster-than relation has previously been developed that compares the worst-case efficiency of asynchronous systems. This approach reveals that pipelining does not improve efficiency in general; that it does so in practice depends on assumptions about the user behaviour. As a case study for testing under such assumptions, we adapt the PAFAS-approach to a setting where user behaviour is known to belong to a specific, but often occurring class of request–response behaviours. Just as the testing preorder in classical testing, the original faster-than relation is qualitative. We give it a quantitative reformulation for the general approach; based on this, we demonstrate in our case study how to determine an asymptotic performance measure for finite-state processes. With this result, we can show that pipelining indeed improves efficiency in our setting, and we discuss additional examples.