Datamation: A Quarter of a Century and Four Orders of Magnitude Later

The combination of the high-performance psort sorting library and of a carefully tuned desktop-class cluster allowed us to improve the previous record on the Datamation sort benchmark by over an order of magnitude, sorting a million 100 byte records from disk to disk in a few dozen milliseconds. Of the many implementation and configuration choices we faced, the most crucial were judicious data placement and access patterns on disk, adoption of UDP sockets instead of MPI, careful pruning of virtually all system daemons, and rejection of ``on demand'' frequency scaling.