Supercomputer Ranking Offers Clues About Chips, China

By Don Clark

If doubts lingered about a major shift in supercomputer technology, the latest ranking Monday of the 500 largest scientific systems should dispel them–as well as any fears that China might claim a lead in the field anytime soon.

The latest Top500 list–compiled twice a year based on results of standard speed tests–anoints a machine called Titan at Oak Ridge National Laboratory as the speediest on the planet. This wasn’t too much of a surprise based on the lab’s recent comments about the system.

But the Titan’s ascendance nevertheless is a milestone for efforts to popularize system designs that use two varieties of chips to get computing work done faster. While most supercomputers still lean heavily on the PC-style x86 microprocessors sold by Intel and Advanced Micro Devices , more specialized chips are also being added to achieve greater leaps in performance within a reasonable power budget.

Titan, an upgrade of a Cray system called Jaguar, adds new AMD chips but gets most of its speed from a new Nvidia chip family that is based on the technology used to provide sophisticated graphics in videogames. Nvidia on Monday is providing the first details of the new Tesla chips, the K20 and K20X, which the company says are three times faster than prior-generation products.

The system, which edged out an IBM system called Sequoia at Lawrence Livermore National Laboratory for the top ranking, scored a ranking on a benchmark test called Linpack of 17.59 petaflops, or quadrillions of scientific calculations per second.

In all, 62 systems on the latest Top500 list use some sort of additional accelerator or coprocessor chip, up from 58 systems in the list released six months ago.

Another sign of the times is the Dell system that ranked No. 7 on the latest list–Stampede, which is currently being installed at the Texas Advanced Computing Center. Besides the latest Intel Xeon chips, the system exploits a new coprocessor called Xeon Phi that is based on x86 technology rather than an entirely new type of computing engine.

Not until the eighth position on the list do we find a system in China. That machine, the Tianhe-1A, set off considerable hand-wringing among some researchers about threats to U.S. dominance when it took the No. 1 spot on the list in November 2010. But there seems to have been little progress since then; while machines like Sequoia and Titan have set new records, the Tianhe-1A is the only Chinese system in the Top Ten.

To be sure, China still ranks No. 2 in terms of the number of supercomputers installed, no small feat. But the country’s 72 systems falls far short of the 251 running in the United States, while Japan–which operates the No. 3 machine–remains ahead of China in terms of the aggregate performance of the systems in use. Germany, in fact, placed two machines ahead of the Tianhe-1A–both supplied by IBM.

Among system makers, IBM and Hewlett-Packard remain No. 1 and No. 2 in the field. Cray, which takes its name from the late supercomputer designer Seymour Cray, has a much smaller number of systems. But Titan allowed the company to increase its share of the Top500 total performance to 17.4% from 8.8%.

The Top500 list, which is marking its 20th anniversary this month, is compiled by researchers Hans Meuer of the University of Mannheim, Germany; Erich Strohmaier and Horst Simon of Lawrence Berkeley National Laboratory; and Jack Dongarra of the University of Tennessee, Knoxville.