No abstract available.

Much of the improvement in computer performance over the last twenty years has come from faster transistors and architectural advances that increase parallelism. Historically, parallelism has been exploited either at the instruction level with a grain-size of a single instruction or by partitioning applications into coarse threads with grain-sizes of thousands of instructions. Fine-grain threads fill the parallelism gap between these extremes by enabling tasks with run lengths as small as 20 cycles. As this fine-grain parallelism is orthogonal to ILP and coarse threads, it complements both methods and provides an opportunity for greater speedup. This paper describes the efficient communication and synchronization mechanisms implemented in the Multi-ALU Processor (MAP) chip, including a thread creation instruction, register communication, and a hardware barrier. These register-based mechanisms provide 10 times faster communication and 60 times faster synchronization than mechanisms that operate via a shared on-chip cache. With a three-processor implementation of the MAP: fine-grain speedups of 1.2-2.1 are demonstrated on a suite of applications.

Abstract This paper describes an experimental message‐driven programming system for fine‐grain multicomputers. The initial target architecture is the J‐machine designed at MIT. This machine combines a unique collection of architectural features that include fine‐grain processes, on‐chip associative memory; and hardware support for process synchronization. The programming system uses these mechanisms via a simple message‐driven process model that blurs the distinction between processes and messages: messages correspond to processes that are executed elsewhere in the network. This model allows code and data to be distributed across the computers in the machine, and is supported at every stage of the program development cycle. The prototype system we have developed includes a basic set of programming tools to support the model; these include a compiler, linker, archiver, loader and microkernel. Although the concepts are language independent, our prototype system is based on GNU‐C.