Studies in Markov models of computer systems

Abstract

A new general model of I/O - CPU interation is described. The model is a discrete Markov process, and takes into account mean CPU time between physical I/O requests, mean I/O service times for each device, single or double buffering, and CPU queue discipline. A simple method of finding the steady state probability vector is shown. The utilization results are calculated and compared to, for three CPU queue disciplines, and for various service times, the results of earlier analytical models, with some interesting outcomes. The new model is limited presently to small systems (i.e., five or less tasks, and six or less I/O queues) due to the number of states necessary to model a large system.