* The next example illustrates a time-shared computer facility considered by Adiri and Avi-Itzhak(1969). A company has a * computer system consisting of a single central processing unit (CPU) and n terminals. The operator of each terminal "thinks" * for an amount of time that is an exponential random variable with a mean of 25seconds and then sends to the CPU a job having * service time distributed exponentially with mean=0.8seconds. Arriving jobs join a single queue for the CPU but are served in * a round-robin rather than FIFO manner. That is, the CPU allocates to each jobs a maximum service quantum of length q=0.1 * second. If the remaining service time of a job (s) is no more than q, the CPU spends s seconds plus a fixed swap time x=0.015 * second, processing the job, which then returns to its terminal. However, if s>q. the CPU spends q+x second processing the * job, which then joins the end of the queue, and its remaining service time is decremented by q seconds. This process is * repeated until the job's service is eventually completed at which point it returns to its terminal, whose operator begins * another think time. *
** We simulate this system for 1000 job completions. and estimate the expected average response times of these jobs, the * expected time-average number of jobs waiting in queue and the expected utilization of the CPU. All terminals are in the think * state at t=0. The company would like to know how many terminals it can have on its system and still provide users with an * average response time of no more than 30 seconds. *
* Copyright (c) 2002-2020 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See * for project information https://simulation.tudelft.nl. The DSOL * project is distributed under a three-clause BSD-style license, which can be found at * * https://simulation.tudelft.nl/dsol/3.0/license.html. *
* @author Peter Jacobs * @author Alexander Verbraeck */ package nl.tudelft.simulation.examples.dsol.timesharedcomputer;