If it's the SC18 supercomputing conference, then there must be lists. The twice-yearly show is most famous for the Top500 list of the world's fastest supercomputers that use the Linpack parallel Fortan benchmark, a list that helps the industry gauge progress in performance, the growing influence of new technologies like GPU accelerators from Nvidia and AMD and the rise of new architectures, as marked this year by the introduction of the first supercomputer on the list powered by Arm-based processors. The "Astra" supercomputer, built by Hewlett Packard Enterprise and deployed at the Sandia National Laboratories, runs on 125,328 Cavium ThunderX2 cores and now sits in the number 205 slot. The list also helps fuel the ongoing global competition for supercomputer supremacy, with the United States this year finally retaking the top spot from China's Sunway TaihuLight in July with the Summit system based on IBM Power9 and Nvidia Volta compute engines, and then Sierra, a similarly architected machine, taking the number-two slot at this week's SC18 show in Dallas, pushing TaihuLight to number-three. However, China now claims 227 systems – or about 45 percent of the total number – on the Top500 list, with the United States dropping to an all-time low of 109, or 22 percent. The Green500 ranks supercomputers based on power efficiency.