Twice a year, Top500.org publishes a list of supercomputing benchmarks from sites around the world; the new results are in. Reader jbrodkin writes "Microsoft says a Windows-based supercomputer has broken the petaflop speed barrier, but the achievement is not being recognized by the group that tracks the world's fastest supercomputers, because the same machine was able to achieve higher speeds using Linux. The Tokyo-based Tsubame 2.0 computer, which uses both Windows and Linux, was ranked fourth in the world in the latest Top 500 supercomputers list. While the computer broke a petaflop with both operating systems, it achieved a faster score with Linux, denying Microsoft its first official petaflop ranking." Also in Top-500 news, reader symbolset writes with word that "the Chinese Tianhe-1A system at the National Supercomputer Center in Tianjin takes the top spot with 2.57 petaflops. Although the US has long held a dominant position in the list things now seem to be shifting, with two of the top spots held by China, one by Japan, and one by the US. In the Operating System Family category Linux continues to consolidate its supercomputing near-monopoly with 91.8% of the systems — up from 91%. High Performance Computing has come a long way quickly. When the list started as a top-10 list in June of 1993 the least powerful system on the list was a Cray Y-MP C916/16526 with 16 cores driving 13.7 RMAX GFLOP/s. This is roughly the performance of a single midrange laptop today."