Chinese supercomputer retains 'world's fastest' title, beating US and Japanese competition The Tianhe-2 was built by China's National University of Defence Technology in Guangzhou and is capable of operating at 33.86 petaflop/s. This is the equivalent of performing 33,863 trillion calculations per second and is almost double the score achieved by the second most powerful machine: the American Titan supercomputer, which clocked in at 17.59 petaflop/s. The list of the world's fastest supercomputer is compiled biannually by the University of Mannheim in Germany, using a test known as the Linpack benchmark. Despite a Chinese supercomputer holding the top-spot, the US still dominates the list overall, accounting for 265 of the 500 computers ranked. In geographical terms, America is followed by Europe (102 machines, down from 112) and then Asia (115 systems, down from 118). However, computer scientists have also criticized the metrics used by the test, pointing out that the single petaflops figure does not always translate directly into a useful supercomputer. "We need a more practical measurement that reflects the real use of these supercomputers based on their most important applications," Dr Alessandro Curioni, head of the computational sciences at IBM's Zurich research lab, told the BBC. Although the Tianhe-2 (it means "Milkyway 2") has the highest score in terms of raw processing power, Curioni notes that there are problems with running any computer efficiently. For example, although the Tianhe-2 may be capable of processing at some given high speed, it might not be able to reach these peaks if it cannot deliver the data to its processors fast enough. However, the symbolic importance of operating the world's "fastest" computer means that any proposed changes to how rankings are compiled could be met with "resistance." The top ten most powerful supercomputers: Tianhe-2 (China) 33.86 petaflop/s Titan (US) 17.59 petaflop/s Sequoia (US) 17.17 petaflop/s K computer (Japan) 10.51 petaflop/s Mira (US) 8.59 petaflop/s Piz Daint (Swiss) 6.27 petaflop/s Stampede (US) 5.17 petaflop/s Juqueen (Germany) 5.09 petaflop/s Vulcan (US) 4.29 petaflop/s SuperMuc (Germany) 2.90 petaflop/s