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How Supers Are Being Niched

Supercomputers are being niched across the board by supersubstitutes that provide a user essentially the same service but at much lower entry and use costs. In addition, all the other forms of computers, including


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mainframes with vector facilities, minis, superminis, minisupers, ordinary workstations, and PCs, offer substitutes. Thus, the supercomputer problem (i.e., the lack of the U.S.'s ability to support them in a meaningful market fashion) is based on economics as much as on competition.

Numerous machines types are contenders as supersubstitutes. Here are some observations on each category.

Workstations

Workstations from companies like Digital Equipment Corporation (DEC), the Hewlett-Packard Company, Silicon Graphics Inc., and Sun Microsystems, among others, provide up to 10 per cent of the capacity of a CRAY Y-MP processor. But they do it at speeds of less than 0.3 per cent of an eight-processor Y-MP LINPACK peak and at about two per cent the speed of a single-processor Y-MP on the LINPACK 100-×-100 benchmark. Thus, while they may achieve impressive scalar performance, they have no way to hit performance peaks for the compute-intensive programs for which the vector and parallel capabilities of supercomputers were developed. As a result, they are not ideal as supersubstitutes. Nevertheless, ordinary computers like workstations, PCs, minicomputers, and superminis together provide most of the technical computing power available today.

Minicomputers and Superminis

These machines provide up to 20 per cent of the capacity of a CRAY-MP processor. But again, with only 0.25 per cent the speed of the LINPACK peak of the Cray, they are also less-than-ideal supercomputer substitutes.

Mainframes

IBM may be the largest supplier of supercomputing power. It has installed significant computational power in its 3090 mainframes with vector-processing facilities. Dataquest has estimated that 250 of the 750 3090-processors shipped last year had vector-processing capability. Although a 3090/600 has 25 per cent of the CRAY Y-MP's LINPACK peak power, its ability to carry out a workload, as measured by Livermore Loops, is roughly one-third that of a CRAY Y-MP/8.

But we see only modest economic advantages and little or no practical benefit to be derived from substituting one centralized, time-shared resource for another. For numeric computing, mainframes are not the best performers in their price class. Although they supply plenty of computational power, they rarely hit the performance peaks that supercomputer-class applications demand. The mainframes from IBM—and


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even the new DEC 9000 series—suffer from the awkwardness of traditional architecture evolution. Their emitter-coupled-logic (ECL) circuit technology is costly. And the pace of improvement in ECL density lags far behind the rate of progress demonstrated by the complementary-metaloxide-semiconductor (CMOS) circuitry employed in more cost-effective and easier-to-use supersubstitutes.

Massively Data-Parallel Computers

There is a small but growing base of special-purpose machines in two forms: multicomputers (e.g., hundreds and thousands of computers interconnected) and the SIMD (e.g., the Connection Machine, MasPar), some of which supply a peak of 10 times a CRAY Y-MP/8 with about the same peak-delivered power (1.5 GFLOPS) on selective, parallelized applications that can operate on very large data sets. This year a Connection Machine won the Bell Perfect Club Prize[*] for having the highest peak performance for an application. These machines are not suitable for a general scientific workload. For programs rich in data parallelism, these machines can deliver the performance. But given the need for complete reprogramming to enable applications to exploit their massively parallel architectures, they are not directly substitutable for current supercomputers. They are useful for the highly parallel programs for which the super is designed. With time, compilers should be able to better exploit these architectures that require explicitly locating data in particular memory modules and then passing messages among the modules when information needs to be shared.

The most exciting computer on the horizon is the one from Kendall Square Research (KSR), which is scalable to over 1000 processors as a large, shared-memory multiprocessor. The KSR machine functions equally well for both massive transaction processing and massively parallel computation.

Minisupercomputers

The first viable supersubstitutes, minisupercomputers, were introduced in 1983. They support a modestly interactive, distributed mode of use and exploit the gap left when DEC began in earnest to ignore its


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technical user base. In terms of power and usage, their relationship to supercomputers is much like that of minicomputers to mainframes. Machines from Alliant Computer Systems and CONVEX Computer Corporation have a computational capacity approaching one CRAY Y-MP processor.

Until the introduction of graphics supercomputers in 1988, minisupers were the most cost-effective source of supercomputing capacity. But they are under both economic and technological pressure from newer classes of technical computers. The leading minisuper vendors are responding to this pressure in different ways. Alliant plans to improve performance and reduce computing costs by using a cost-effective commodity chip, Intel's i860 RISC microprocessor. CONVEX has yet to announce its next line of minisupercomputers; however, it is likely to follow the Cray path of a higher clock speed using ECL.

Superworkstations

This machine class, judging by the figures in Table 1, is the most vigorous of all technical computer categories, as it is attracting the majority of buyers and supplying the bulk of the capacity for high-performance technical computing. In 1989, superworkstation installations reached more users than the NSF centers did, delivering four times the computational capacity and power supplied by the CRAY Y-MP/8.

Dataquest's nomenclature for this machine class—superworkstations—actually comprises two kinds of machines: graphics supercomputers and superworkstations. Graphics supercomputers were introduced in 1988 and combine varying degrees of supercomputer capacity with integral three-dimensional graphics capabilities for project and departmental use (i.e., multiple users per system) at costs ranging between $50,000 and $200,000. Priced even more aggressively, at $25,000 to $50,000, superworkstations make similar features affordable for personal use.

Machines of this class from Apollo (Hewlett-Packard), Silicon Graphics, Stardent, and most recently from IBM all provide between 10 and 20 per cent of the computational capacity of a CRAY Y-MP processor, as characterized by the Livermore Loops workload. They also run the LINPACK 100-×-100 benchmark at about 12 per cent of the speed of a one-processor Y-MP. While the LINPACK peak of such machines is only two per cent of an eight-processor CRAY Y-MP, the distributed approach of the superworkstations is almost three times more cost effective. In other words, users spending the same amount can get three to five times


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as much computing from superworkstations and graphics supercomputers than from a conventional supercomputer.

In March 1990, IBM announced its RS/6000 superscalar workstation, which stands out with exceptional performance and price performance. Several researchers have reported running programs at the same speed as the CRAY Y-MP. The RS/6000's workload ability measured by the Livermore Loops is about one-third that of a CRAY Y-MP processor.

Superworkstations promise the most benefits for the decade ahead because they conjoin more leading-edge developments than any other class of technical computer, including technologies that improve performance and reduce costs, interactivity, personal visualization, smarter compiler technologies, and the downward migration of super applications. More importantly, superworkstations provide for interactive visualization in the same style that PCs and workstations used to stabilize mainframe and minicomputer growth. Radically new applications will spring up around this new tool that are not versions of tired 20-year-old code that ran on the supercomputer, mainframe, and minicode museums. These will come predominantly from science and engineering problems, but most financial institutions are applying supercomputers for econometric modeling, work optimization, portfolio analysis, etc.

Because these machines are all based on fast-evolving technologies, including single-chip RISC microprocessors and CMOS, we can expect performance gains to continue at the rate of over 50 per cent a year over the next five years. We'll also see continuing improvements in clock-rate growth to more than 100 megahertz by 1992. By riding the CMOS technology curve, future superworkstation architectures will likely be able to provide more power for most scientific applications than will be available from the more costly multiple-chip systems based on arrays of ECL and GaAs (gallium arsenide) gates. Of course, the bigger gains will come through the use of multiple of these low-cost processors for parallel processing.


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