Approximate Queuing Models for Multiprogramming Computer Systems

Abstract

In a multiprogramming computer system several jobs may be handled simultaneously by utilizing the central processing unit in processing one job while other jobs are being served by the peripheral devices. Our analysis of such a computer system proceeds in the following way. First we view the system as a closed queuing network with a fixed number of jobs, and obtain exact results for customer cycle times and server utilization. Then we use these results to develop an approximate model for the open system where the computer is fed by randomly arriving jobs. For the approximate model we obtain simple closed-form expressions for the delay distribution. The approximate model is then tested by comparing its result for the expected sojourn time to the exact results that we obtain for some special cases.