ABSTRACT
Hard real-time systems are subject to stringent timing constraints which are dictated by the surrounding physical environment. We assume that a real-time system consists of a number of tasks, which realize the required functionality. A schedulability analysis for this set of tasks and a given hardware has to be performed in order to guarantee that all the timing constraints of these tasks will be met (“timing validation”). Existing techniques for schedulability analysis require upper bounds for the execution times of all the system’s tasks to be known. ese upper bounds are commonly called the worst-case execution times (WCETs), a misnomer that causes a lot of confusion and will therefore not be adopted in this presentation. In analogy, lower bounds on the execution time have been named best-case execution times, (BCET). ese upper bounds (and lower bounds) have to be
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“safe,” i.e., they must never underestimate (overestimate) the real execution time. Furthermore, they should be tight, i.e., the overestimation (underestimation) should be as small as possible.
