The twice yearly ranking of the largest supercomputers was released at the International Supercomputing conference Wednesday (June 18). It was the first version to report power consumption figures.

As expected the IBM Roadrunner system passed the petaflops marker, hitting 1.026 PFlops in a Linpack test conducted at an IBM research facility in New York. The system uses a mix of Opteron processors from Advanced Micro Devices and a variant of the IBM Cell processor also used in the Sony Playstation 3.

The system surpassed another IBM design, the BlueGene/L system at Lawrence Livermore National Laboratory. Blue Gene/L hits 478.2 teraflops and has been at the top of the list since November 2004.

A number of other supercomputers are gearing up for a run at the petaflops milestone, but it's not clear whether any will hit the mark when the list is updated in the fall. "Achieving this level will be a non-trivial task for November," said Erich Strohmaier, a computer scientist at Lawrence Berkeley National Laboratory and a founding editor of the Top 500 list.

A total of 374 systems (74.8 percent) are now using Intel processors, up from 354 systems (70.8 percent) in the list six months ago, the largest share for Intel in the Top 500 to date. The number of systems using Intel Harpertown and Clovertown quad-core chips showed the fastest growth rising in six months from 102 to 252 systems.

Multicore processors now dominate the Top 500. A total of 282 systems on the list now use quad-core processors. Another 204 systems are using dual-core CPUs, and only eleven use single core processors.

IBM Power processors passed the AMD Opteron family in the latest ranking with 68 systems (13.6 percent) using Power chips, up from 61 systems (12.2 percent) six months ago. Opteron chips appeared in 56 systems (11.2 percent), down from 78 systems (15.6 percent) six months ago.

"AMD was ahead with its dual-core offerings but lost a lot of momentum and credibility with the delays in its quad-core processors," said Strohmaier. Meanwhile, "Intel managed its quad-core entrance very cleverly, starting with the pragmatic double-die Woodcrest capable of doing four floating point operations per core per cycle, double the performance for both Intel's and AMD's dual-core chips," he added.