Reliable Mode Changes in Real-Time Systems with Fixed Priority or EDF Scheduling

Abstract

Many application domains require adaptive real-time embedded systems that can change their functionality over time. In such systems it is not only necessary to guarantee timing constraints in every operating mode, but also during the transition between different modes. Known approaches that address the problem of timing analysis over mode changes are restricted to fixed priority scheduling policies. In addition, most of them are also limited to simple periodic event stream models and therefore, they can not faithfully abstract the bursty timing behavior which can be observed in embedded systems. In this paper, we propose a new method for the design and analysis of adaptive multi-mode systems that supports any event stream model and can handle earliest deadline first (EDF) as well as fixed priority (FP) scheduling of tasks. We embed the analysis method into a well-established modular performance analysis framework based on Real-Time Calculus and prove its applicability by analyzing a case study.