A Hybrid Shared Memory/Message Passing Parallel Machine

Current and emerging high-performance parallel computer architectures generally implement one of two types of communication mechanisms: shared memory (SM) or message passing (MP). In this paper we propose a hybrid SM/MP architecture together with a hybrid SM/MP programming model, that we believe effectively combines the advantages of each system. The SM/MP architecture contains both a high-performance coherence protocol for shared memory, and message-passing primitives that coexist with the coherence protocol but have no coherence overhead. The SM/MP programming model provides a framework for safely and effectively using the SM/MP communication primitives. We illustrate the use of the model and primitives to reduce communication overhead in SM systems. 1. Introduction Two data communication mechanisms currently dominate in existing and emerging large-scale parallel computers. In the Message Passing (or Distributed Memory) model, each processor has its own private main memory and comm..