There are two major problems with the current state of the art in high-performance computing. First, the cost of the very highest end machines lies far beyond the point where widespread deployment is feasible, and second (and more critical) the software environments for these machines are awkward at best, and capable of eking out only fractions of the performance that the hardware is capable of supplying. The thesis of this is that much of the problem stems from our historical separation of memory and CPU logic parts. Individual CPU clock rates and internal architectures continue to accelerate, and thus require ever increasing amounts of bandwidth from the memory subsystem. These rates have far exceeded the bandwidth capabilities of our densest DRAM memory parts (needed to control system costs), and the gap will widen over time. The net effect is complex memory hierarchies, which in turn drives cost and software complexity in addressing these hierarchies efficiently. A new technology is emerging to counter this fundamental defect: the combination on one chip of both dense DRAM and very significant amounts of logic. This capability permits new architectures termed Processing-In-Memory (PIM) to place computing either right next to, or even inside of, the memory macros, where there are huge amounts of raw bandwidth. The first such chip, EXECUBE, integrated onto a 4Mbit DRAM chip 8 complete CPUs configured in a 3D binary hypercube, and was capable of being used as a one chip-type building block for MPPs of both MIMD and SIMD organization. The objective of this project is to look at utilizing PIM technology potentials over the next decade and demonstrate that they promise efficient solution. The approach to be used involves configuring and studying some "point design" MPPs with 100 tera(fl)op potential for several interesting classes of problems, and then utilizing the novel features of these architectures, along with matching system software and software development tools, to attack them in ways that may permit not only exceptional performance, but also greatly simplified programming environments.
