ABSTRACT
This chapter introduces a simple process model, more suitable for reasoning and analysis. In a similar way, an abstract scheduling model specifies a scheduling algorithm and its associated analysis methods without going into the fine details of its implementation. The chapter introduces one of the simplest process models, called the basic process model, along with the nomenclature associated with it. It is used as a foundation to talk about the most widespread real-time scheduling algorithms and gain an insight into their properties. Since some of its underlying assumptions are quite unrealistic, it will also be progressively refined and extended to make it adhere better to what real-world processes look like. The chapter specifies how one of the simplest and most intuitive real-time scheduling methods, the cyclic executive, works. It completely builds the time diagram before the system is ever executed, and hence, it is possible to put into action sophisticated layout algorithms without incurring any significant overhead at runtime.
