Hard Real-Time Computing Systems: Predictable Scheduling Algorithms and Applications

538 Pages·2011·3.87 MB·English

by  Giorgio C. Buttazzo (auth.)

Hard Real-Time Computing Systems
Real-Time Systems Series
Series Editor
JohnA. Stankovic
UniversityofVirginia,Virginia,USA
Forfurthervolumes:
http://www.springer.com/series/6941
Giorgio C. Buttazzo
Hard Real-Time Computing
Systems
Predictable Scheduling Algorithms
and Applications
Third Edition
Giorgio C. Buttazzo
RETIS Lab
Scuola Superiore Sant’Anna
Pisa
Italy
[e-mail]
ISSN 1867-321X e-ISSN 1867-3228
ISBN 978-1-4614-0675-4 e-ISBN 978-1-4614-0676-1
DOI 10 .1007/978-1-4614-0676-1
Springer New York Dordrecht Heidelberg London

Library of Congress Control Number: 2011937234

© Springer Science(cid:0) +Business Media, LLC 2011

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Printedonacid-freepaper
Springer is part of Springer Science+Business Media (www.springer.com)
CONTENTS
Preface ix
1 A GENERAL VIEW 1
1.1 Introduction 1
1.2 Whatdoesrealtimemean? 4
1.3 Achievingpredictability 13
2 BASIC CONCEPTS 23
2.1 Introduction 23
2.2 Typesoftaskconstraints 25
2.3 Definitionofschedulingproblems 34
2.4 Schedulinganomalies 42
3 APERIODIC TASK SCHEDULING 53
3.1 Introduction 53
3.2 Jackson’salgorithm 54
3.3 Horn’salgorithm 58
3.4 Non-preemptivescheduling 63
3.5 Schedulingwithprecedenceconstraints 70
3.6 Summary 76
4 PERIODIC TASK SCHEDULING 79
4.1 Introduction 79
4.2 Timelinescheduling 84
4.3 RateMonotonicscheduling 86
4.4 EarliestDeadlineFirst 100
4.5 DeadlineMonotonic 103
4.6 EDFwithconstraineddeadlines 110
4.7 ComparisonbetweenRMandEDF 116
v
vi Contents
5 FIXED-PRIORITY SERVERS 119
5.1 Introduction 119
5.2 Backgroundscheduling 120
5.3 PollingServer 121
5.4 DeferrableServer 130
5.5 PriorityExchange 139
5.6 SporadicServer 143
5.7 Slackstealing 149
5.8 Non-existenceofoptimalservers 153
5.9 Performanceevaluation 155
5.10 Summary 157
6 DYNAMIC PRIORITY SERVERS 161
6.1 Introduction 161
6.2 DynamicPriorityExchangeServer 162
6.3 DynamicSporadicServer 167
6.4 TotalBandwidthServer 171
6.5 EarliestDeadlineLateServer 174
6.6 ImprovedPriorityExchangeServer 178
6.7 ImprovingTBS 181
6.8 Performanceevaluation 185
6.9 TheConstantBandwidthServer 189
6.10 Summary 201
7 RESOURCE ACCESS PROTOCOLS 205
7.1 Introduction 205
7.2 Thepriorityinversionphenomenon 206
7.3 Terminologyandassumptions 209
7.4 Non-PreemptiveProtocol 210
7.5 HighestLockerPriorityProtocol 212
7.6 PriorityInheritanceProtocol 214
7.7 PriorityCeilingProtocol 226
7.8 StackResourcePolicy 234
7.9 Schedulabilityanalysis 246
7.10 Summary 247
Contents vii
8 LIMITED PREEMPTIVE SCHEDULING 251
8.1 Introduction 251
8.2 Non-preemptivescheduling 257
8.3 Preemptionthresholds 261
8.4 DeferredPreemptions 266
8.5 Tasksplitting 270
8.6 Selectingpreemptionpoints 274
8.7 Assessmentoftheapproaches 279
9 HANDLING OVERLOAD CONDITIONS 287
9.1 Introduction 287
9.2 Handlingaperiodicoverloads 293
9.3 Handlingoverruns 316
9.4 Handlingpermanentoverloads 326
10 KERNEL DESIGN ISSUES 349
10.1 Structureofareal-timekernel 349
10.2 Processstates 351
10.3 Datastructures 356
10.4 Miscellaneous 361
10.5 Kernelprimitives 366
10.6 Intertaskcommunicationmechanisms 385
10.7 Systemoverhead 392
11 APPLICATION DESIGN ISSUES 397
11.1 Introduction 398
11.2 Timeconstraintsdefinition 401
11.3 Hierarchicaldesign 408
11.4 Arobotcontrolexample 413
12 REAL-TIME OPERATING SYSTEMS AND
STANDARDS 419
12.1 Standardsforreal-timeoperatingsystems 419
12.2 Commercialreal-timesystems 428
12.3 Linuxrelatedreal-timekernels 432
12.4 Open-sourcereal-timeresearchkernels 437
12.5 DevelopmentTools 452
viii Contents
13 SOLUTIONS TO THE EXERCISES 457
GLOSSARY 487
REFERENCES 497
INDEX 515
PREFACE
Real-time computingplays a crucial role in our society since an increasing number
of complex systems rely, in part or completely, on computer control. Examples of
applications that require real-time computing include nuclear power plants, railway
switchingsystems,automotiveandavionicsystems,airtrafficcontrol,telecommuni-
cations,robotics,andmilitarysystems. Inthelastseveralyears,real-timecomputing
has beenrequiredin newapplicationsareas, suchas medical equipments,consumer
electronics,multimediasystems,flightsimulationsystems,virtualreality,andinterac-
tivegames.
Despitethis largeapplicationdomain,mostofthecurrentreal-timesystemsarestill
designed and implemented using low-level programming and empirical techniques,
without the support of a scientific methodology. This approach results in a lack of
reliability,whichincriticalapplicationsmaycauseseriousenvironmentaldamageor
evenlossoflife.
Thisbookisabasictreatiseonreal-timecomputing,withparticularemphasisonpre-
dictableschedulingalgorithms. Themainobjectivesofthebookaretointroducethe
basic concepts of real-time computing, illustrate the most significant results in the
field, andprovidethebasic methodologiesfordesigningpredictablecomputingsys-
temsusefulinsupportingcriticalcontrolapplications.
Thisbookiswrittenforinstructionaluseandisorganizedtoenablereaderswithouta
strongknowledgeofthesubjectmattertoquicklygraspthematerial. Technicalcon-
ceptsareclearlydefinedatthebeginningofeachchapter,andalgorithmdescriptions
arecorroboratedthroughconcreteexamples,illustrations,andtables.
ix