Supercomputers are normally large dedicated machines tuned to solve computationally intensive scientific challenges. Grid computing, on the other hand, pools thousands of ordinary PCs at computing centres around the world to tackle problems that can be split up into many relatively small chunks. Yet the processing power of individual computing centres on the Grid is growing rapidly, reaching levels comparable with top supercomputers. This was illustrated recently, when CERN for the first time entered the prestigious TOP500 Supercomputing Sites list, which ranks the fastest supercomputers in the world.

CERN reached a respectable 115th position in the TOP500 list released at the end of June. CERN's cluster, consisting of 340 servers with two Intel Xeon 5160 (Woodcrest) processors, with a total of 1360 cores, is one of only a few commodity clusters in the list. It reached a performance in the standard benchmark used for the TOP500 of just over 8.3 teraflops. The fastest supercomputer, an IBM BlueGene machine at Lawrence Livermore Laboratory, managed 280 teraflops with 131,072 cores. However, apart from the top three, all machines were rated below 100 teraflops.

It is significant that CERN achieved this result using only about 20% of the computing power available in its computer centre, which in turn is only a fraction of the computing power available on the EGEE Grid infrastructure. Another important feature of the result is that no special tuning of the CERN computers was required to achieve this result using the TOP500 benchmarks, even though the high-throughput requirements of Grid computing are very different from the low-latency requirements of normal supercomputers.

The TOP500 project was started in 1993 to provide a reliable basis for tracking and detecting trends in high-performance computing. Twice a year, a list of the sites operating the 500 most-powerful computer systems is assembled and released. The best performance on a benchmark, known as LINPACK, is used as a performance measure for ranking the computer systems.

• The full rankings list is available at www.top500.org/lists/2007/06.