HieraGen: Automated Generation of Concurrent, Hierarchical Cache Coherence Protocols

We present HieraGen, a new tool for automatically generating hierarchical cache coherence protocols. HieraGen’s inputs are the simple, atomic, stable state protocols for each level of the hierarchy. HieraGen’s output is a highly concurrent hierarchical protocol, in the form of the finite state machines for all of the cache and directory controllers. HieraGen thus reduces the complexity that architects face, by offloading the challenging tasks of composing protocols and managing concurrency. Experiments show that HieraGen can automatically generate correct-by-construction MOESI family of hierarchical protocols with dozens of states and hundreds of transitions. We have verified all of the generated protocols for safety and deadlock freedom using a model checker.