CSC/ECE 506 Fall 2007/wiki1 5 jp07

Section 1.1.4: Supercomputers.

Compare current supercomputers with those of 10 yrs. ago. Update Figures 1.10 to 1.12 with new data points. For 1.12, consult top500.org

Definitions of Supercomputer

Supercomputer

• "The class of fastest and most powerful computers available." [1]
• "An extremely fast computer that can perform hundreds of millions of instructions per second." [2]
• "A time dependent term which refers to the class of most powerful computer systems world-wide at the time of reference." [3]
• "An extremely fast computer that can perform hundreds of millions of instructions per second." [4]

It is obvious that the term supercomputer has a definition that takes many forms. For some it refers to a definite set of goals such as, x number of instructions per second. For others it is about having the best possible performance of any computer at the current time. Still for some, the primary factor is price. In general, a supercomputer receives its classification because it is both one of the most expensive computers and one of the most powerful computers.

LINPACK Benchmark

The main metric for evaluating the effectiveness of supercomputers has long been the LINPACK benchmark suite. [5] In general this benchmark attempts to solve a dense system of linear equations and measure's the processors speed at completing the task. Although this is a very narrow field, it proves to give a industry standard metric for supercomputers and is used for ranking by top sites such as the Top 500.

Note that benchmark performance with the LINPACK benchmarks is usually given in FLOPS, floating point operation per second. This is not necessarily the best overall metric for measuring system performance [6] but still proves useful because of the nature and specific target of the LINPACK benchmark.

Cray Supercomputing

Perhaps the most famous name in relation to supercomputing is Seymour Cray. Commonly referred to as the "father of supercomputing" Cray fueled the interest in supercomputing by developing the Cray-1 in 1976 for Los Alamos National Laboratory. At the time it sold for $8.8 million, had a 8MB memory, and performed at 160 MFLOPS. [7] Cray founded his own business which eventually became Cray Inc. [8] Even today Cray manufactured computers have contenders for the fastest supercomputers in the world. Their overall market share has declined however, with only 2.2% of the world's top 500 belonging to Cray manufactured machines. [9]

The Evolution of the Supercomputer

Innovation in computer architecture always begins with supercomputers. The world of supercomputers is a "playground" for new architecture, with concepts being introduced long before they are used in standard microprocessors. In the past this was especially true as the 1960's introduced supercomputers with pipelined instruction processing and dynamic instruction scheduling. Then in the 1970's vector processors began to emerge as the major force for supercomputing architecture. Since that time massively parallel processors have begun to dominate the market share of supercomputers. The world's top supercomputers today can have up to 2048 processors running in parallel.

Evolution of Architecture

As mentioned already, the types of systems have varied greatly among supercomputers, and the last 10 years have been no different. As the following graphs show, Parallel Vector Processors (PVPs) and Symettric shared memory multiprocessors (SMPs) have died out. MPPs have seen a decline in popularity and given way to a majority of the market coming from clustered architectures. [10]

Evolution of Performance

Since the Cray1 there has been significant strides made in architecture performance. In 1995 the fastest supercomputers in the world, the T94 was fastest, had a uniprocessor performance around 1,000 MFLOPS for the LINPACK benchmark. In the recent June 2007 reports, the fastest supercomputer in the world, the Blue/Gene L System topped 280.6 TFLOPS. A massive improvement over 10 years.

To see the improvement since 1993, Top 500 has a chart that illustrates the improvement of the top supercomputers in the world located here. Note that since 2004, the maximum performance has leveled off as no major developments of new supercomputers have broken the threshold of the reigning champion, the Blue/Gene L.

Blue/Gene L System

Currently the fastest supercomputer in the world, the Blue/Gene L System is located in the Terascale Simulation Facility at Lawrence Livermore National Laboratory. Developed by IBM, the computer performs many complex tasks such as scientific simulations that include "ab initio molecular dynamics; three-dimensional (3D) dislocation dynamics; and turbulence, shock, and instability phenomena in hydrodynamics. It is also a computational science research machine for evaluating advanced computer architectures." [11]

The following list taken from Top 500 lists some of the main features of the Blue Gene System:

• "Nodes are configured as a 32 x 32 x 64 3D torus; each node is connected in six different directions for nearest-neighbor communications"
• "A global reduction tree supports fast global operations such as global max/sum in a few microseconds over 65,536 nodes"
• "Multiple global barrier and interrupt networks allow fast synchronization of tasks across the entire machine within a few microseconds"
• "1,024 gigabit-per-second links to a global parallel file system to support fast input/output to disk"

Source: Top500.org [12]

Additional Links

• Top 500
• Cray Supercomputing
• Supercomputing History
• Wiki Article on Supercomputers