The Thinking Machines CM-5 is one of the first of a new generation of massively parallel systems.To assess the scalability of the CM-5's computation and interprocessor communication rates, we used a sem"es of benchmarks to measure the performance of the CM-5 data and control networks, the node vector units, and the balance of computation and communication.At the application level, we found the achievable communication bandwidth and processing rates to be roughly fifiy percent and forty percent, respectively, of the corresponding theoretical peak rates.Our early assessment is that the CM-5 is scalable but that a better balance of communication and processing rates would increase its effectiveness. 1

In distributed-memory multiprocessors, remote memory accesses incur larger delays than local accesses. Hence, insightful allocation and access of distributed data can yield substantial performance gains. The authors argue for the use of dynamic data management policies encapsulated within individual distributed data structures. Distributed data structures offer performance, flexibility, abstraction, and system independence. This approach is supported by data from a trace-driven simulation study of parallel scientific benchmarks. Experimental data on memory locality, message count, message volume, and communication delay, suggest that data-structure-specific data management is superior to a single, system-imposed policy.>

We propose a machine architecture for a high-performance processing node for a message-passing, MIMD concurrent computer. The principal mechanisms for attaining this goal are the direct execution and buffering of messages and a memory-based architecture that permits very fast context switches. Our architecture also includes a novel memory organization that permits both indexed and associative accesses and that incorporates an instruction buffer and message queue. Simulation results suggest that this architecture reduces message reception overhead by more than an order of magnitude.