The problem of multiprogram scheduling on a single processor is studied from the viewpoint...

and related areas. Application requirements motivated the major research areas, processor scheduling and non-uniform memory management, as these areas contain the most important problems raised by the changing design and use of multiprocessors.

Scheduling theory maintains that there are fundamental similarities in problems of sequence that transcend the characteristics of the particular tasks to be ordered or the resources to be used. Traditionally, scheduling policies are implemented using algorithms; we study scheduling algorithms to discover the various properties of the schedules they produce. To facilitate analysis the policies are typically limited to homogeneous task sets (e.g., all periodic tasks) and consider only one or very few task attributes. In some cases the results are so attractive that the task sets of systems are made to fit the algorithm rather than using a policy more appropriate to the system. We therefore make the following observation: if scheduling policies are driven by how well they can be expressed and analyzed, then we need a more general framework for expressing scheduling policies. We introduce the Importance Abstraction as a general scheduling framework. The scheduling algorithm is invariant: ...

C.M. de Jongh Proefschrift Technische Universiteit Delft - Met lit. opg. Met samenvatting in het Nederlands ISBN 90-9015128-1 NUGI 811 Keywords: distributed systems, scheduling, queueing theory, simulation Correspondence: JanDeJongh@ACM.Org c # 2002 by J.F.C.M. de Jongh All rights reserved. No part of this publication may be reproduced or distributed in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without the prior written permission from the publisher: J.F.C.M. de Jongh. Printed by Ponsen en Looijen B.V., Wageningen, The Netherlands Voor John Rotsvast verankerd blijf je in onze gedachten Contents Contents vii 1 Introduction 1 1.1 SystemModels ................................. 1 1.1.1 TheUniprocessorModel........................ 2 1.1.2 TheMultiprocessorModel....................... 2 1.1.3 TheDistributed-SystemModel ...........

ion The importance abstraction is a framework within which we can describe scheduling policies by focusing on the importances of the tasks within a system. The system has a goal and the tasks within the system are processed with the intent of meeting the system goal. A task within the system is viewed as "important" to the system vis-a-vis 16 how that task can contribute to accomplishing the system goal. As the system progresses and its state changes, various tasks become more or less important to the system. The importance abstraction is a framework for expressing those conditions under which tasks within a system become important to the system. The importance abstraction includes within its framework sets of importance functions that describe the tasks within a system, and a scheduler which uses the importance functions to determine which tasks should receive service. By using this abstraction to consider scheduling problems, we shift the emphasis from the analysis of the schedulin...