A Framework for Correctness Criteria on Weak Memory Models

Abstract

The implementation of weak (or relaxed) memory models is standard practice in modern multiprocessor hardware. For efficiency, these memory models allow operations to take effect in shared memory in a different order from that which they occur in a program. A number of correctness criteria have been proposed for concurrent objects operating on such memory models, each reflecting different constraints on the objects which can be proved correct. In this paper, we provide a framework in which correctness criteria are defined in terms of two components: the first defining the particular criterion (as it would be defined in the absence of a weak memory model), and the second defining the particular weak memory model. The framework facilitates the definition and comparison of correctness criteria, and encourages reuse of existing definitions. The latter enables properties of the criteria to be proved using existing proofs. We illustrate the framework via the definition of correctness criteria on the TSO (Total Store Order) weak memory model.