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Special K

June 23, 2011

No, this article isn't about ketamine hydrochloride, sometimes called "Special K;" nor is it about the breakfast cereal that gave me super powers when I was a youth. It's about the fastest computer in the world, at least for the present. This is the K Computer of the RIKEN Advanced Institute for Computational Science, Kobe, Japan, which is rated at eight petaflops, or the equivalent performance of about a million desktop computers.[1-5] The "K" designation comes from the Japanese word, "Kei," for ten quadrillion, or ten times 1015, the 2012 target for the number of floating point operations per second for this computer.[4]

Some news stories are periodic. You can be sure of the typical tax stories around the mid-April filing deadline. In the days when people actually mailed their tax forms, there was obligatory video of people in line at the post office waiting to get their deadline postmark. It was likewise a tradition in New Jersey, where I live, to see annual spring video of people in row boats on the main streets of their just flooded towns.

Supercomputer stories are periodic, also. There will always be another, faster computer. One popular exhortation is to be wary of the computing gap between the US and other countries; and, yes, supercomputers predict the weather, but they are used also in weapons design. Less attention is given to the fact that without a corp of capable programmers, these newer computers may only execute programs as well as the ones that they replaced.

Cray-1 Supercomputer

Cray-1 supercomputer on display at the École polytechnique fédérale de Lausanne, Lausanne, Switzerland.

The Cray-1 benchmarked at just 80 megaflop/sec.

(Via Wikimedia Commons)

Supercomputers rankings are posted in the periodically updated TOP500 List of the fastest supercomputers. The 37th edition of this list was released on June 20, 2011, at the 2011 International Supercomputing Conference in Hamburg, Germany.[1] The rating is impartially determined by the speed of execution of the Linpack benchmark that I wrote about in a previous article (Benchmarks, November 17, 2010).

The TOP500 list is updated every six months. It's compiled by computer scientists at the University of Tennessee, the National Energy Research Scientific Computing Center at Lawrence Berkeley National Laboratory, and the University of Mannheim.[4] Jack Dongarra, a professor of electrical engineering and computer science at the University of Tennessee, maintains the database.[3]

Perhaps more significant than who won first place is the fact that all computers in the top ten achieved petaflop performance for the first time. Here's the current top ten list:[1]

1.K Computer8.2RIKEN Advanced Institute for Computational Science, Kobe, Japan
2.Tianhe-1A2.6National Supercomputing Center, Tianjin, China
3.Cray Jaguar1.75U.S. Department of Energy, Oak Ridge National Laboratory
4.Nebulae1.27National Supercomputing Center, Shenzen, China
5.Tsubame 2.01.19Tokyo Institute of Technology, Tokyo, Japan
6.Cray Cielo1.11Los Alamos National Laboratory, Los Alamos, New Mexico
7.Pleiades1.09NASA Ames Research Center, Moffett Field, California
8.Hopper1.054DOE National Energy Research Scientific Computing Center, Oakland, California
9.Tera 1001.05Commissariat à l'énergie atomique et aux énergies alternatives, Essonne, France
10.Roadrunner1.04Los Alamos National Laboratory, Los Alamos, New Mexico

There's been much press about using Graphics processing unit (GPU) chips in computing applications. The Tianhe-1A is built from NVIDIA GPU chips, and nineteen systems on the TOP500 list use GPU chips. The K Computer, which was built by Fujitsu, is composed of 68,544 "traditional" CPU chips, the eight core SPARC64 VIIIfx. This results in a computer with a phenomenal 548,352 cores, which is nearly twice the number of any other supercomputer in the TOP500 list. The Japanese government has invested about $1.25 billion in the K Computer project as it attempts to position Japan as the world supercomputer leader.[4]

The particular SPARC chips manufactured by Fujitsu run at 2 GHz. The basic module from which the K Computer is built is a four CPU, water-cooled blade server with 512 gigaflop double-precision floating point capability. The K Computer uses a torus network architecture described previously by Fujitsu.[5]

Notable is the fact that, although the K Computer was designed to be energy-efficient, it still consumes 9.89 megawatts! Energy consumption is becoming an important factor in supercomputing. Twenty-nine of the 500 listed computers consume more than a megawatt of power each.[1] The average power consumption of computers on the top ten list is 4.3 megawatts, which is much higher than the 3.2 megawatts of the last list, published six months ago.[1] A megawatt translates to hundreds of dollars per hour operating cost; and this figure doesn't include necessary cooling systems.

There's no economic slowdown in the supercomputing arena. The total computing capacity of the present TOP500 list is 58.88 petaflops, an increase of 34.7% from November 2010, and an increase of 81.7% per cent from June, 2010.[5] The present list averages 15,550 cores per system, which is up from 13,071 in November, 2010, and 10,267 in June, 2010.[1]

The US is losing its supercomputing lead. At 256, it has just a few more than half of the present top 500 supercomputers, which is down from 274 last November. China has 62, Germany has 30, the United Kingdom has 27, Japan has 26, and France has 25.[5]


  1. Erich Strohmaier, "Japan Reclaims Top Ranking on Latest TOP500 List of World's Supercomputers," TOP500 Press Release, June 16, 2011.
  2. Verne G. Kopytoff, "Japanese 'K' Computer Is Ranked Most Powerful," The New York Times, June 19, 2011.
  3. Tom Chivers, "Japanese supercomputer 'K' is world's fastest," Telegraph (UK), June 20, 2011.
  4. Daisuke Wakabayashi, "Japanese Supercomputer Claims World's Top Spot," Wall Street Journal, June 20, 2011.
  5. Timothy Prickett Morgan, "Japan takes the Top 500 lead with K super - The mother of all Sparc systems," Register (UK), June 20, 2011.

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