Unique information of a super computer

Over the years many definitions for the notion of “supercomputer” have been given. Some of the most well-known are “the fastest existing computer at any point in time” and “a computer that has a performance level that is typically hundreds of times higher than that of normal commodity computers.” Both definitions have their drawbacks. In the first definition the object in question is a moving target because of the fast rate at which new computers are conceived and built. Therefore, with this definition it is hard to know whether a certain computer is still the supercomputer or a new, even faster one has just emerged.

The second definition is vague because it presupposes that one can easily determine the performance level of a computer, which is by no means true, and furthermore, the performance factor that should discriminate between supercomputers and commodity computers is also not easily established. Indeed, it is not even straightforward to define what is meant by the term “commodity computer.”
Should a supercomputer be measured against a PC, used mainly for word processing, or against a workstation used for technical computations?

Faster Standard Computing

Still, it is obvious that, whatever definition is used, one expects supercomputers to be significantly faster on any task than the computers to which one is normally exposed. In that sense the second definition is more appropriate. Therefore, we adhere mainly to this rather vague definition, with the addition that supercomputers have a special architecture to enable them to be faster than the standard computing equipment we use every day.
The architecture, that is, the high-level structure in terms of its processors, its memory modules, and the interconnection network between these elements, largely determines its performance and, as such, whether or not it is a supercomputer. Other defining features of the architecture are the instruction set of the computer and the accessibility of the components in the architecture from the programmer’s point of view.

Moore’s Law

It is good to realize that even for commodity computers the speed is continuously increasing because of the processor speed, which, according to Moore’s law, is doubling every 18 months. Therefore, supercomputers need to be at least at the same technology curve with respect to the processor speed and, in addition, employ their architectural advantage to stay ahead of commodity computers. This is also evident from the clock cycle in both commodity computers and supercomputers: in both types of systems the clock cycle is in the range of 1–3 nsec, and it is not likely that future supercomputers will contain processors with significantly faster processors because of the enormous additional costs incurred in the development and fabrication.

Coordination of Processors

As it stands, nowadays the architectural advantage of supercomputers is due almost entirely to parallelism, i.e., many processors in a supercomputer are commonly involved in a single computational task. Ideally, the speedup that is achieved increases linearly with the number of processors that are contributing to such a computational task. Because of the time spent in the coordination of the processors, this linear increase in speed is seldomly observed. Nevertheless, parallelism enables us to tackle computational problems that would be simply un-thought of without it.