Models of multiprocessor computing

Today's options for high-performance computing include message-passing MPP systems, clusters of workstations, shared-memory multiprocessors, and parallel vector processors. Shared-memory multiprocessors provide the most general-purpose programming model, but generally suffer from limited scalability. New multiprocessor cache coherence protocols together with high-performance CMOS VLSI and interconnects are enabling a new class of machine that scales the shared-memory paradigm. The author introduces the scalable shared-memory multiprocessor (SSMP) and SGI's new Origin servers based on this technology. The Origin machines are highly modular and permit a single system to grow from a cost-effective deskside uniprocessor to a supercomputer with hundreds of processors and hundreds of gigabytes of shared-memory. Nodes within the system provide a peak of 50 GB/sec of memory bandwidth and are connected by fat hypercube network that has a peak bisection bandwidth of 25 GB/sec. These capabilities also enable new levels of I/O performance including file servers with sustained bandwidths in excess of 500 MByte/sec and networking interfaces such as SuperHIPPI that can source and sink data at up to 800 MB/sec simultaneously. He concludes the talk with a look at the future of multiprocessing. He predicts a merger of the HPC computing models on SSMP and clusters of SSMP systems.