A Distributed Real-Time Operating System with Location-Transparent System Calls for Task Management and Inter-task Synchronization

The paper presents a distributed real-time operating system (DRTOS) for hard real-time embedded systems such as automotive control systems. A real-time control application program is usually designed as a set of tasks that cooperate with each other through the mechanism of a real- time operating system. In a distributed embedded control system, location-transparent mechanisms are required because the tasks are allocated to multiple nodes. We have developed a DRTOS that provides location-transparent system calls for task management and inter-task synchronization. The DRTOS is an extension to OSEK OS, which is a standard operating system in the automotive control domain. The DRTOS manages distributed tasks based on the global time supported by the clock synchronization of FlexRay, which is a real-time network based on a TDMA (Time Division Multiple Access) protocol. By using the DRTOS, we can develop a distributed control application program with location-transparent system calls. We can also reallocate the tasks of the application program just by reconfiguration, without rewriting the source code. The worst case response time of a remote system call of the DRTOS is predictable if the FlexRay communication is well configured.