Exact Interference of Tasks With Variable Rate-Dependent Behavior

In embedded real-time systems, the schedulability analysis is an important method to verify whether the real-time constraints are satisfied. Especially, engine control systems in the automotive industry are particular challenging regarding their real-time analysis. Some of the tasks of such systems are triggered at predetermined angular values of the crankshaft. Thus, the frequency of activation increases for higher crankshaft rotation speeds. To avoid overloads, these tasks reduce their computational demand for higher rotation speeds. The variable rate-dependent behavior (VRB) task model has been proposed as a means of modeling such rate-dependent behavior. In this paper, we introduce a new method for the exact computation of interference for VRB-tasks. A number of experimental results are reported to validate our approach and compare it with existing analysis. These experimental results illustrate that our method outperforms previous results in terms of precision and runtime.