Producer-consumer communication in distributed shared memory multiprocessors

Abstract

The shared memory abstraction supported by hardware based distributed shared memory (DSM) multiprocessors is an inherently consumer driven means of communication. When a process requires data, it retrieves them from the global shared memory. In distributed cache coherent systems, the data may reside in a remote memory module or in the producer's cache. Producer initiated mechanisms reduce communication latency by sending data to the consumer as soon as they are produced. We classify producer initiated mechanisms as implicit or explicit, according to whether the producer must know the identity of the consumer when data are transmitted. Explicit schemes include data forwarding and message passing. Implicit schemes include update based coherence, selective updates, and cache based locks. Several of these mechanisms are evaluated for performance and sensitivity to network parameters, using a common simulated architecture and a set of application kernel benchmarks. StreamLine, a cache based message passing mechanism, provides the best performance on the benchmarks with regular communication patterns. Forwarding write and cache based locks are also among the best performing producer initiated mechanisms. Consumer initiated prefetch, however, has good average performance and is the least expensive to implement.