Analysis of a Drum Input/Output Queue Under Scheduled Operation in a Paged Computer System

Abstract

Properly scheduling the usage of input output devices is an important aspect of the design of modern multiprogramming systems featuring a paged environment. In this paper magnetic drums in the role of auxiliary memories are studied in the context of these systems. It is the nature of the drum, its usage by the system, and the organization of information on the drum are discussed in the light of current system designs. Mathematical models are then defined such that two extremes in scheduling disciplines are represented in a system in which page requests are assumed to arrive singly and at random. The analysis leads to results for a measure of drum utilization, a generating function for the queue length probabilities in equilibrium, the mean queue length, and the mean waiting time. Finally, the significance of the results is discussed along with some examples.