A Simple Method for Parameterized Verification of Cache Coherence Protocols

We present a simple method for verifying the safety properties of cache coherence protocols with arbitrarily many nodes. Our presentation begins with two examples. The first example describes in intuitive terms how the German protocol with arbitrarily many nodes can be verified using a combination of Murphi model checking and apparently circular reasoning. The second example outlines a similar proof of the FLASH protocol. These are followed by a simple theory based on the classical notion of simulation proofs that justifies the apparently circular reasoning. We conclude the paper by discussing what remains to be done and by comparing our method with other approaches to the parameterized verification of cache coherence protocols, such as compositional model checking, machine-assisted theorem proving, predicate abstraction, invisible invariants, and cut-off theorems.