“One reader who commented on the blog post joked that Tokyo
officials “didn’t have enough licenses to run [Windows] on that
many.”“But it turns out a software bug prevented the Windows HPC
Server run from matching Linux’s speed and ability to run across
more nodes. The bug was not in Windows HPC Server itself but rather
in a software package Microsoft designed to run the Top 500
benchmarking test.“Satoshi Matsuoka, professor at the Tokyo Institute of
Technology, explained it to me today at the SC10 supercomputing
conference in New Orleans, saying Linux’s victory “was purely by
chance.”