The economics of large-memory computations

Abstract

We propose and justify an economic theory to guide memory system design, operation and analysis. Our theory treats memory random-access latency, and its cost per installed megabyte, as fundamentals. We introduce incentives in our economic theory, and side-constraints in our analytic model of hierarchical memory to ensure sufficient memory bandwidth and processor speed in any "well-formed" system of a given latency and size. We suggest, on the basis of our theory, that computer users should be charged a "rental" cost, proportional to their use of the total capacity in a hierarchical memory system. Finally, we use our theory to compare the cost/performance of various large-memory organisations such as PoPCs (piles of PCs), NOWs (networks of workstations), SMPs (shared memory multiprocessors), MPPs (massively parallel processors), and even Cray-class vector supercomputers.