Fastest supercomputers
By Asha

The TOP500 list of the world’s super computers has been released and a Japanese supercomputer capable of performing more than 8 quadrillion calculations per second (petaflop/s) is the new number one system in the world, putting Japan back in the top spot for the first time since the Earth Simulator was dethroned in November 2004. The system, called the K Computer, is at the RIKEN Advanced Institute for Computational Science (AICS) in Kobe.

The 37th edition of the closely watched list was released Monday, June 20, at the 2011 International Supercomputing Conference in Hamburg. The ranking of all systems is based on how fast they run Linpack, a benchmark application developed to solve a dense system of linear equations.

For the first time, all of the top 10 systems achieved petaflop/s performance – and those are also the only petaflop/s systems on the list. The U.S. is tops in petaflop/s with five systems performing at that level; Japan and China have two each, and France has one.

Bumped to second place after capturing No. 1 on the previous list is the Tianhe-1A supercomputer the National Supercomputing Center in Tianjin, China, with a performance at 2.6 petaflop/s. Also moving down a notch was Jaguar, a Cray supercomputer at the U.S. Department of Energy’s (DOE’s) Oak Ridge National Laboratory, at No. 3 with 1.75 petaflop/s.

Rounding out the Top 10 are Nebulae at China’s National Supercomputing Center in Shenzen (1.27 petaflop/s), Tsubame 2.0 at the Tokyo Institute of Technology (1.19 petaflop/s), Cielo at Los Alamos National Laboratory in New Mexico (1.11 petaflop/s), Pleiades at the NASA Ames Research Center in California (1.09 petaflop/s), Hopper at DOE’s National Energy Research Scientific Computing Center (NERSC) in California (1.054 petaflop/s), Tera 100 at the CEA (Commissariat à l'énergie atomique et aux énergies alternatives) in France (1.05 petaflop/s), and Roadrunner at Los Alamos National Laboratory in New Mexico (1.04 petaflop/s).

The K Computer, built by Fujitsu, currently combines 68544 SPARC64 VIIIfx CPUs, each with eight cores, for a total of 548,352 cores—almost twice as many as any other system in the TOP500. The K Computer is also more powerful than the next five systems on the list combined.

The K Computer’s name draws upon the Japanese word "Kei" for 10^16 (ten quadrillions), representing the system's performance goal of 10 petaflops. RIKEN is the Institute for Physical and Chemical Research. Unlike the Chinese system it displaced from the No. 1 slot and other recent very large system, the K Computer does not use graphics processors or other accelerators. The K Computer is also one of the most energy-efficient systems on the list.

Some other highlights from the newest List

•The two Chinese systems at No. 2 and No. 4 and the Japanese Tsubame 2.0 system at No. 5 are all using NVIDIA GPUs to accelerate computation, and a total of 19 systems on the list are using GPU technology.
•China keeps increasing its number of systems and is now up to 62, making it clearly the No. 2 country as a user of HPC, ahead of Germany, UK, Japan and France.
•Intel continues to provide the processors for the largest share (77.4 percent) of TOP500 systems. Intel’s Westmere processors increased their presence in the list strongly with 169 systems, compared with 56 in the last list.
•Quad-core processors are used in 46.2 percent of the systems, while already 42.4 percent of the systems use processors with six or more cores.
•Cray defended the No. 2 spot in market share by total against Fujitsu, but IBM stays well ahead of either. Cray’s XT system series remains very popular for big research customers, with three systems in the TOP 10 (one new and two previously listed).