A Definition and Classification of Timing Anomalies

Timing anomalies are characterized by counterintuitive timing behaviour. A locally faster execution leads to an increase of the execution time of the whole program. The presence of such behaviour makes WCET analysis more difficult: It is not safe to assume local worst-case behaviour wherever the analysis encounters uncertainty. Existing definitions of timing anomalies are rather imprecise and intuitive in nature. Some do not cover all kinds of known timing anomalies. After giving an overview of related work, we give a concise formal definition of timing anomalies. We then begin to identify different classes of anomalies. One of these classes, coined Scheduling Timing Anomalies, coincides with previous restricted definitions.