Sequential Consistency in Distributed Systems : Theory and Implementation

Recently, distributed shared memory (DSM) systems have received much attention because such an abstraction simpliies programming. It has been shown that many practical applications using DSMs require competing operations. We have aimed at unifying theory and implementations of protocols for sequential consistency , which provides competing operations. The results are useful not only to clarify previously proposed implementations but also to develop new eecient implementations for consistency criteria which provide competing operations, such as sequential consistency, weak ordering (with sequential consistency for competing accesses), and release consistency (with sequential consistency for competing accesses). By adopting concepts from concurrency control, we have developed theory for sequential consistency, called a sequentializability theory. This paper rst presents the sequentializability theory, and then demonstrates the correctness of existing protocols using the theory. Finally, the paper presents new protocols which require sig-niicantly less communication than previously proposed protocols in systems which do not provide hardware atomic broadcasting facilities. Mots-cl e : coh erence s equentielle, m emoire distribu ee partag ee.