Processor Utilization in Multiprogramming Systems via Diffusion Approximations

Abstract

Cyclic queuing systems have been proposed by several authors in the study of the behavior of multiprogrammed computer systems. Programs in the system wait for service at the central processor unit (CPU); then, after page fault or input-output request at a data transmission unit (DTU), the process repeats until the program completes. Semi-Markov analysis of such systems, based on the apparently plausible assumption of independently but exponentially distributed CPU burst time, and independent, but nearly constant DTU tune may be conducted. This paper presents some very simple approximations based on a continuous-state approximation—the simple diffusion with two reflecting barriers—to describe the CPU utilization. Computational experience from which the quality of the approximations can be assessed is reported.