Handling Interrupts with Static Scheduling in an Automotive Vehicle Control System

The requirements of industrial applications only rarely permit the exclusive use of single paradigms in the development of real-time systems. Product cost, reuse of existing solutions, and efficiency require diverse, or even opposing methods to coexist or to be integrated. In this paper, we deal with one problem encountered during the development of a real-time system for motion control in automotive vehicles, the integration of static scheduling and interrupts. The user mandates pre run-time scheduling for a number of reasons, e.g., predictability, testability and low run-time overhead. However, the interrupt overhead can not be ignored in a safety critical system, and therefor has to be accounted for when creating a static schedule. We propose a method that combines static scheduling and run-time interrupts by applying standard static scheduling techniques and exact analysis. The appropriateness of this method is underlined by successful industrial deployment.