SCHEDULING ALGORITHMS AND OPERATING-SYSTEMS SUPPORT FOR REAL-TIME SYSTEMS

This paper summarizes the state of the real-time field in the areas of scheduling and operating system kernels. Given the vast amount of work that has been done by both the operations research and computer science communities in the scheduling al ea, we discuss four paradigms underlying the scheduling approaches and present several exemplars of each. The Soul paradigms are: static table-driven scheduling, static priority preemptive scheduling, dynamic planning-based scheduling, and dynamic best effort scheduling. In the operating system context, we argue that most of the proprietary commercial kernels as well as real-time extensions to time-sharing operating system kernels do not fit the needs of predictable real-time systems. We discuss several research kernels that al e currently being built to explicitly meet the needs of real-time applications.