Exact Interference of Adaptive Variable-Rate Tasks under Fixed-Priority Scheduling

Engine control applications require the execution of tasks activated in relation to specific system variables, such as the crankshaft rotation angle. To prevent possible overload conditions at high rotation speeds, such tasks are designed to vary their functionality (hence their computational requirements) for different speed ranges. Modeling and analyzing such a type of tasks poses new research challenges in the schedulability analysis that are now being addressed in the real-time literature. This paper advances the state of the art by presenting a method for computing the exact worst-case interference of such adaptive variable-rate tasks under fixed priority scheduling, enabling a tight analysis and design of engine control applications.