A Cyclic-Queue Model of System Overhead in Multiprogrammed Computer Systems

A probabilistic model is presented of a multiprogrammed computer system operating under demand paging. The model contains an explicit representation of system overhead, the CPU requirements and paging characteristics of the program load being described statistically. Expressions for steady-state CPU problem program time, CPU overhead time, and channel utilization are obtained. Some numerical results are given which quantify the gains in CPU utilization obtained from multiprogramming. It is also pointed out heuristically and demonstrated numerically that an actual decrease in CPU utilization results if there is too much overhead associated with multiprogramming and if the average time between page exceptions decreases too rapidly with increasing number of multiprogrammed jobs. © 1971, ACM. All rights reserved.