The world’s Largest Sharp Brain Virtual Experts Marketplace Just a click Away
Levels Tought:
Elementary,Middle School,High School,College,University,PHD
| Teaching Since: | May 2017 |
| Last Sign in: | 398 Weeks Ago, 4 Days Ago |
| Questions Answered: | 66690 |
| Tutorials Posted: | 66688 |
MCS,PHD
Argosy University/ Phoniex University/
Nov-2005 - Oct-2011
Professor
Phoniex University
Oct-2001 - Nov-2016
Scheduling to minimize average completion time
Suppose you are given a set S = {a1, a2, ..., an} of tasks, where task ai requires pi units of processing time to complete, once it has started. You have one computer on which to run these tasks, and the computer can run only one task at a time. Let ci be the completion time of task ai , that is, the time at which task ai completes processing. Your goal is to minimize the average completion time, that is, to minimize . For example, suppose there are two tasks, a1 and a2, with p1 = 3 and p2 = 5, and consider the schedule in which a2 runs first, followed by a1. Then c2 = 5, c1 = 8, and the average completion time is (5 + 8)/2 = 6.5.
a. Give an algorithm that schedules the tasks so as to minimize the average completion time. Each task must run non-preemptively, that is, once task ai is started, it must run continuously for pi units of time.
Prove that your algorithm minimizes the average completion time, and state the running time of your algorithm.
b. Suppose now that the tasks are not all available at once. That is,each task has a release time ri before which it is not available to be processed. Suppose also that we allow preemption, so that a task can be suspended and restarted at a later time. For example, a task ai with processing time pi = 6 may start running at time 1 and be preempted at time 4. It can then resume at time 10 but be preempted at time 11 and finally resume at time 13 and complete at time 15.Task ai has run for a total of 6 time units, but its running time has been divided into three pieces. We say that the completion time of ai is 15. Give an algorithm that schedules the tasks so as to minimize the average completion time in this new scenario. Prove that your algorithm minimizes the average completion time, and state the running time of your algorithm.
Hel-----------lo -----------Sir-----------/Ma-----------dam-----------Tha-----------nk -----------You----------- fo-----------r u-----------sin-----------g o-----------ur -----------web-----------sit-----------e a-----------nd -----------and----------- ac-----------qui-----------sit-----------ion----------- of----------- my----------- po-----------ste-----------d s-----------olu-----------tio-----------n.P-----------lea-----------se -----------pin-----------g m-----------e o-----------n c-----------hat----------- I -----------am -----------onl-----------ine----------- or----------- in-----------box----------- me----------- a -----------mes-----------sag-----------e I----------- wi-----------ll