Using simple abstraction to guide the reinvention of computing for parallelism

The sudden shift from single-processor computer systems to many-processor parallel computing systems requires rein-venting much of Computer Science (CS): how to actually build and program the new parallel systems. CS urgently requires convergence to a robust parallel general-purpose platform that provides good performance and is easy to pro-gram. Unfortunately, this same objective has eluded decades of parallel computing research. Now, continued delays and uncertainty could start affecting important sectors of the economy. This paper advocates a minimalist stepping-stone: settle first on a simple abstraction that encapsulates the new interface between programmers, on one hand, and system builders, on the other hand. This paper also makes several concrete suggestions: (i) the Immediate Concurrent Execution (ICE) abstraction as a candidate for the new abstraction, and (ii) the Explicit Multi-Threaded (XMT) general-purpose parallel platform, under development at the University of Maryland, as a possi-ble embodiment of ICE. ICE and XMT build on a formidable body of knowledge, known as PRAM (for parallel random-access machine, or model) algorithmics, and a latent, though not widespread, familiarity with it. Ease-of-programming, strong speedups and other attractive properties of the ap-proach suggest that we may be much better prepared for the challenges ahead than many realize