A Survey of Verification Techniques for Cache Coherence Protocols

In this paper, we present a comprehensive survey of various approaches for the verification of cache coherence protocols based on state enumeration, (symbolic) model checking and symbolic state models. Since these techniques search the state space of the protocol exhaustively, the amount of memory required to manipulate the state information and the verification time grow very fast with the number of processors and the complexity of the protocol mechanisms. To be successful for systems of arbitrary complexity, a verification technique must solve this so-called state space explosion problem. The emphasis of our discussion is on the underlying theory in each method to handle the state space explosion problem, and to formulate and check the safety properties (e.g., data consistency) and the liveness properties (absence of deadlock and livelock). We compare the efficiency and discuss the limitations of each technique in terms of memory and computation time. Also, we discuss issues of generality, applicability, automaticity and amenity for existing tools in each class of methods. No method is truly superior because each method has its own strengths and weaknesses. Finally, refinements which can further reduce the verification time and/or the memory requirement are also discussed. Corresponding author: Fong Pong. Email: [email protected]