Voluntary Preemption: a Tool Tn The Design Of Hard Real-Time Systems

A new technique for scheduling hard real-time systems is proposed. We term this technique as voluntary preemption as it allows the user to determine the points at which the execution of a process can be preempted. There are several advantages of this technique. First of all, the internal structure of the processes can be used in determining the points where a process may be preempted. This permits, among other things, that critical sections are not preempted as well as identifying points at which a process should be preempted. Secondly, overhead cost of context switching can be taken into account realistically without sacrificing performance. Finally, since the overhead cost of context switching depends on the point (in the execution) where a process is preempted, this technique allows the preemption points to be chosen to reduce the overhead cost of context switching. These various considerations about where a process can be preempted, can be incorporated into an automatic tool to aid in the design of real-time systems.