Using coarse-grained abstractions to verify linearizability on TSO architectures

Abstract

Most approaches to verifying linearizability assume a sequentially consistent memory model, which is not always realised in practice. In this paper we study correctness on a weak memory model: the TSO (Total Store Order) memory model, which is implemented in x86 multicore architectures. Our central result is a proof method that simplifies proofs of linearizability on TSO. This is necessary since the use of local buffers in TSO adds considerably to the verification overhead on top of the already subtle linearizability proofs. The proof method involves constructing a coarse-grained abstraction as an intermediate layer between an abstract description and the concurrent algorithm. This allows the linearizability proof to be split into two smaller components, where the effect of the local buffers in TSO is dealt with at a higher level of abstraction than it would have been otherwise.