Process-Algebraic Analysis of Timing and Schedulability Properties

Process algebras, such as CCS [13], CSP [9], ACP [3] and others, are a well-established class of modeling and analysis formalisms for concurrent systems. They can be considered as high-level description languages consisting of a number of operators for building processes including constructs for defining recursive behaviors. They are accompanied by semantic theories which give precise meaning to processes, translating each process into a mathematical object on which rigorous analysis can be performed. In addition, they are associated with axiom systems which prescribe the relations between the various constructs and can be used for reasoning about process behavior. During the last two decades, they have been extensively studied and they have proved quite successful in the modeling and reasoning about various aspects of system correctness. In a process algebra, there exist a number of elementary processes as well as operators for composing processes into more complex ones. A system is then modeled as a term in this algebra. The rules in the operational semantics of an algebra define the steps that a process can make in terms of the steps of the subprocesses. When a process takes a step, it evolves into another process. The set of processes that a given process P can evolve into by performing a sequence of steps defines a state space of P . The state space is represented as a labeled transition system (LTS) with steps serving as labels. The notation for a process P performing a step a and evolving into a process P ′ is P a −→ P ′. State space exploration techniques allow us to analyze properties of processes, for example, identify