Schedule Design to Guarantee Freedom of Interference in Mixed Criticality Systems 2012-01-0036

The integration of mixed-criticality software according to safety standards like ISO 26262 generates new, parasitic mutual effects within the involved software architectures. In this situation, established schedule design patterns like RMS fail to deliver both efficiency and safety, in particular the freedom of interference. In today's practice of building a schedule, certain such measures to fulfill these safety requirements can conflict with efficiency requirements. The target of this paper is to present a sound approach of how to solve such requirement conflicts and to build up schedules that are safe and also efficient. We present a general early-stage procedure to build safe, certifiable, and efficient schedules. The procedure is based on the established design patterns and adds guidelines on how to exploit additional options in both schedule design and software partitioning. This procedure was validated against typical real-world systems and one example is presented.