IBM's Roadrunner and Cray's Jaguar have retained their No. 1 and No. 2 rankings on the Top500 supercomputer list, which is drawn up twice a year.
Roadrunner, the first machine to break the petaflop barrier a year ago, registered 1.105 petaflops to top the June 2009 list, published on Tuesday. (One petaflop is 1,000 trillion floating-point operations per second.) Built in 2008, the system is housed at the US Department of Energy's (DOE) Los Alamos National Laboratory.
Jaguar, installed at DOE's Oak Ridge National Laboratory, reached 1.059 petaflops. The result was a repeat of the rankings in November, when the machines led with the same results.
Eight of the top 10 systems in the June list are housed in the United States, while two machines are based in Germany.
In third spot was another Big Blue machine — a new BlueGene/P system called Jugene, installed at the Forschungszentrum Juelich (FZJ) in Germany. It achieved 825.5 teraflops and has a theoretical peak performance of just above 1 petaflop, according to the Top500 Web site.
FZJ is also home to Juropa, the new No. 10 system, which registered 274.8 teraflops. It is built from Bull Novascale and Sun Microsystem SunBlade x6048 servers.
Two other high-performance computing (HPC) systems in the top 10 are new: the Kraken, a Cray XT5 machine installed at the National Institute for Computational Sciences at the University of Tennessee, at No. 6; and anIBM BlueGene/P system called Dawn, installed at the DOE's Lawrence Livermore National Laboratory, at No. 9.
The highest-ranked UK supercomputers are two machines at the European Centre for Medium-Range Weather Forecasts in Reading, which took 25th and 26th place.
Overall, there were significant gains in performance, said the Top500 team. The last system on the June list would have been listed at No. 274 in the November rankings, the team said.
The United States' share of supercomputers stood unchanged from the previous list at 291, while the European share dropped to 145 from November's 151. Asia was home to 49 of the HPC systems, up from 47.
While IBM is ahead by overall installed performance, its share of the total number of systems on the latest Top500 list was 24 short of rival Hewlett-Packard's 212 systems.
A total of 399 systems, up from 379 previously, are powered by Intel processors. According to an Intel statement on Tuesday, 33 of these machines tap into the Xeon 5500, launched in March.
IBM Power processors were used in 55 systems, down from 60 last November, while AMD's share of the systems decreased by 16, to the current 43.