Impact analysis for timing requirements on real-time systems

The analysis of real-time properties is crucial in safety critical areas, and is particularly difficult for distributed systems as complex interferences between tasks of different priorities can occur. In previous works we have introduced a state-based analysis approach to validate end-to-end deadlines for distributed systems, where the state spaces of all resources, such as processors and buses, are computed in a compositional fashion. For this, abstraction and composition operations were defined to adequately handle task and resource dependencies. During the design process of a system changes occur typically on both the specification and implementation level, such that already performed analyses of the system have to be repeated. In this work, we define a methodology to adequately handle such changes and to determine the minimal part of the affected architecture. For this, we define an appropriate refinement relation between state spaces of the resources. We use contracts to further reduce the re-validation effort. This check takes place at a higher design level, where only the specification is considered.