Epilogue, June 1992

Clusters of 10 to 100 workstations are emerging as a high-performance parallel processing computer—the result of economic realities. For example, Lawrence Livermore National Laboratory estimates spending three times more on workstations that are 15 per cent utilized than it does on supercomputers. Supers cost a dollar per 500 FLOPS and workstations about a dollar per 5000 FLOPS. Thus, 25 times the power is available in their unused workstations as in supers. A distributed network of workstations won the Gordon Bell Prize for parallelism in 1992.

The ability to use workstation clusters is enabled by a number of environments such as Linda, the Parallel Virtual Machine, and Parasoft Corporation's Express. HPF (Fortran) is emerging as a powerful standard to allow higher-level use of multicomputers (e.g., Intel's Paragon, Thinking Machine's CM-5), and this could also be used for workstation clusters as standardization of interfaces and clusters takes place.

The only inhibitor to natural evolution is that government, in the form of the High Performance Computing and Communications (HPCC) Initiative, and especially the Defense Advanced Research Projects Agency, is attempting to "manage" the introduction of massive parallelism by attempting to select winning multicomputers from its development-funded companies. The HPCC Initiative is focusing on the peak TFLOPS at any price, and this may require an ultracomputer (i.e., a machine costing $50 to $250 million). Purchasing such a machine would be a

mistake—waiting a single three-year generation will reduce prices by a least a factor of four.

In the past, the government, specifically the Department of Energy, played the role of a demanding but patient customer, but it never funded product development—followed by managing procurement to the research community. This misbehavior means that competitors are denied the significant market of leading-edge users. Furthermore, by eliminating competition, weak companies and poor computers emerge. There is simply no need to fund computer development. This money would best be applied to attempting to use the plethora of extant machines—and with a little luck, weed out the poor machines that absorb and waste resources.

Whether traditional supercomputers or massively parallel computers provide more computing, measured in FLOPS per month by 1995, is the object of a bet between the author and Danny Hillis of Thinking Machines. Unless government continues to tinker with the evolution of computers by massive funding for massive parallelism, I believe supers will continue as the main source of FLOPS in 1995.