Operating Systems Enhancements for Distributed Shared Memory

Publisher Summary This chapter focuses on distributed shared memory (DSM) systems supported primarily through software modifications to existing virtual memory management facilities, These DSM systems are characterized by a larger unit of sharing, typically at the page level, and are designed for loosely coupled workstation networks. The chapter discusses some of the important issues regarding design and implementation of DSM systems. It discusses techniques to reduce the latency attributable to memory coherence algorithms and the methods to reduce the communication overhead incurred by the underlying network software and hardware. It categorizes the sources of latency reduction as latency stemming from the choice of coherence semantics and the design of the coherence algorithms, latency attributable to communications overhead generated by network software and hardware, and latency because of unnecessary message-passing overhead because of large page sizes and false sharing. The chapter also discusses innovations in the design of DSM systems to minimize the impact of large page sizes and false sharing. It concludes with a summary of the lessons learned and achievements attained in performance during the past five years.