ABSTRACT
In the “old days” of scientific supercomputing roughly between 1975 and 1995, leading-edge high performance systems were specially designed for the HPC market by companies like Cray, CDC, NEC, Fujitsu, or Thinking Machines. Those systems were way ahead of standard “commodity” computers in terms of performance and price. Single-chip general-purpose microprocessors, which had been invented in the early 1970s, were only mature enough to hit the HPC market by the end of the 1980s, and it was not until the end of the 1990s that clusters of standard workstation or even PC-based hardware had become competitive at least in terms of theoretical peak performance. Today the situation has changed considerably. The HPC world is dominated by cost-effective, off-the-shelf systems with processors that were not primarily designed for scientific computing. A few traditional supercomputer vendors act in a niche market. They offer systems that are designed for high application performance on the single CPU level as well as for highly parallel workloads. Consequently, the scientist and engineer is likely to encounter such “commodity clusters” first and only advance to more specialized hardware as requirements grow. For this reason, this chapter will mostly focus on systems based on standard cache-based microprocessors. Vector computers support a different programming paradigm that is in many respects closer to the requirements of scientific computation, but they have become rare. However, since a discussion of supercomputer architecture would not be complete without them, a general overview will be provided in Section 1.6.
