Verification Methods for Weaker Shared Memory Consistency Models

The problem of verifying nite-state models of shared memory multiprocessor coherence protocols for conformance to weaker memory consistency models is examined. We start with W.W. Collier's architectural testing methods and extend it in several non-trivial ways in order to be able to handle weaker memory models. This, our rst contribution, presents the construction of architectural testing programs similar to those constructed by Collier (e.g. the Archtest suite) suited for weaker memory models. Our own primary emphasis has, however, been to adapt these methods to the realm of model-checking. In an earlier e ort (joint work with Nalumasu and Mokkedem), we had demonstrated how to adapt Collier's architectural testing methods to model-checking. Our veri cation approach consisted of abstracting executions that violate memory orderings into a xed collection of automata (called Test Automata) that depend only on the memory model. The main advantage of this approach, called Test Model-checking, is that the test automata remain xed during the iterative design cycle when di erent coherence protocols that (presumably) implement a given memory model are being compared for performance. This facilitates `push-button' re-veri cation when each new protocol is being considered. Our second contribution is to extend the methods of constructing test automata to be able to handle architectural tests for weaker memory models. After reviewing prior work, in this paper we mainly focus on architectural tests for weaker memory models and the new abstraction methods thereof to construct test automata for weaker memory models. An extended version of this paper is available through www.cs.utah.edu/formal_verification/ under `Publications'