Planning the Execution of Task Groups in Real-Time Systems

Many real time applications are designed such that not simply individual tasks but also groups thereof are specified and must be executed satisfying a common real time requirement. Examples are real time transactions executed in a distributed environment, applications with end-to-end constraints and real-time applications with some dependability requirements in which redundancy is introduced for fault tolerance purposes. This paper investigates on the problem of planning groups of tasks in real-time environments. It first discusses the issues related to the design choices and their implications on planning strategies for tasks groups. Then an algorithm for planning groups of tasks is proposed for the specific case of fault tolerant real-time applications where fault tolerance is realised by groups of tasks forming together fault tolerant structures.