Algorithms for dependable hard real-time systems

Hard real-time code is special purpose code whose worst-case performance (worst-case execution time ... WCET) needs to be good and easy to predict. Despite these specific demands on the temporal properties of hard real-time code, real-time programmers often use the same algorithms and programming techniques that have proven effective for non real-time applications. This paper explains the different temporal requirements imposed on real-time resp. non real-time code, and outlines why traditional (non real-time) programming tends to produce code that (a) has a high WCET and (b) is hard to analyse for its WCET Based on these observations the paper proposes an unconventional programming strategy that avoids the shortcomings of traditional coding and yields code that is well-suited for hard real-time systems, i.e., its WCET is short and predictable. The evaluation of a number of examples demonstrates the advantages of the proposed programming strategy on WCET and its predictability.