Deadline-Aware Programming and Scheduling

Deadlines are the most important events in real-time systems. Realtime programs must therefore be aware of deadlines, and be able to identify and react to missed deadlines. Moreover, Earliest Deadline First (EDF) is the most widely studied optimal dynamic scheduling algorithm for uniprocessor real-time systems. In this paper we explore how a resource sharing protocol (called the DFP – Deadline Floor inheritance Protocol), which has been proposed for languages such as Ada, can be incorporated into the language’s definition. We also address the programming of systems that have mixed scheduling (e.g. fixed priority and EDF). The incorporation of the DFP into Ada requires some changes to the current predefined packages. These changes are also of use in supporting the programming of deadline-aware systems even when not scheduling by EDF.