Table Of ContentCONSTRUCTING PREDICTABLE
REAL TIME SYSTEMS
THEKLUWER INTERNATIONALSERIES
IN ENGINEERINGAND COMPUTERSCIENCE
REAL-TIME SYSTEMS
ConsultingEditor
John A.Stankovic
REAL-TIMEUNIXSYSTEMS:DesignandApplicationGuide,
B.Furht,D.Grostick,D. Gluch,G. Rabbat,J. Parker,M. McRoberts,
ISBN: 0-7923-9099-7
FOUNDATIONSOFREAL-TIMECOMPUTING:Schedulingand
ResourceManagement, A. M.vanTilborg,G.M.Koob
ISBN: 0-7923-9166-7
FOUNDATIONSOFREAL-TIMECOMPUTING:Formal
SpecificationsandMethods, A. M.vanTilborg,
ISBN: 0-7923-9167-5
CONSTRUCTING PREDICTABLE
REAL TIME SYSTEMS
by
WolfgangA. Halang
University of Groningen
Alexander D. Stoyenko
New Jersey Institute of Technology
~.
"
SPRINGER SCIENCE+BUSINESS MEDIA, LLC
Library ofCongress Cataloging-in-PublicatioD Data
Halang, Wolfgang A., 1951 -
Constructing predictable real time systems / by Wolfgang A.
Halang, A1cxander D. Stoyenko.
p. cm. -- (The Kluwer international series in engineering and
computer science; 146. Real-time systems)
Inc\udes index.
ISBN 978-1-4613-6803-8 ISBN 978-1-4615-4032-8 (eBook)
DOI 10.1007/978-1-4615-4032-8
1. Real-time data processing. 2. System design. 1. Stoyenko,
A1exander D., 1962 - II. Title. III. Series: K1uwer
international series in engineering and computer science ; SECS
146. IV. Series: K1uwer international series in engineering and
computer science. Real-time systems.
QA76.54.H35 1991
004' .33--dc20 91-19988
CIP
Copyright © 1991 Springer Science+Business Media New York
Originally published by Kluwer Academic Publishers,New York in 1991
Softcover reprint ofthe hardcover Ist edition 1991
AII rights reserved. No part of this publication may be reproduced, stored in a retrieval
system or transmitted in any form or by any means, mechanical, photo-copying, record ing,
or otherwise, without the prior written permission of the publisher, Springer
Science+Business Media, LLC.
Printed on acid-free paper.
To our wives Bertha and Lana
Contents
List of Figures xv
List of Tables XVll
Authors xix
Vorwort
XXI
Foreword
XXllI
Preface and Abstract XXv
Disclaimers and Acknowledgements XXIX
1 Introduction 1
1.1 Motivation 1
1.1.1 A Chemical Process Application 3
1.1.2 A Power Plant Application .. 5
1.1.3 A Fighter Aircraft Application 5
1.1.4 Real Time System Requirements 7
1.2 Predictability and Simplicity . 9
viii Constructing Predictable Real Time Systems
1.3 New Thinking Categories and Optimality Criteria .... 11
1.4 Guiding Principles for Predictable, Verifiable Real Time
Software and Hardware .... 13
1.4.1 Language Assumptions 13
1.4.2 System Software and Hardware Assumptions 15
1.5 Book Outline . 16
2 Real Time Features of High Level Languages 19
2.1 A Representative Real Time Application Design 20
2.2 Historical Development of Real Time Languages 27
2.3 Requirements of a Real Time Language 28
2.4 Review of Existing Languages . 30
2.4.1 Pseudocodes and Assembly Languages 30
2.4.2 FORTRAN 31
2.4.3 JOVIAL .. 31
2.4.4 RTL/l and RTL/2 32
2.4.5 PEARL 32
2.4.6 ILIAD. 33
2.4.7 Modula and Modula-2 33
2.4.8 PORTAL 34
2.4.9 Ada 35
2.4.10 Forth 35
2.4.11 Languages for Programmable Logic Controllers 36
2.4.12 Experimental Hard Real Time Languages 37
2.4.13 Survey Summary. . . . . . . . . . . 38
2.5 Taking a Closer Look at Real-Time Euclid. 40
2.5.1 Language Structure . 40
Contents IX
2.5.2 Real Time Units and Time Functions 41
2.5.3 Absence of Dynamic Data Structures. 42
2.5.4 Time-Bounded Loops 43
2.5.5 Absence of Recursion 44
2.5.6 Processes . 44
2.5.7 Condition Variables 45
2.5.8 Monitors, Signals, Waits and Broadcasts. 47
2.5.9 Exception Handling 48
2.5.10 Summary . 52
2.6 A Second Review - Focusing on Real Time Features 53
2.6.1 Selection of Reviewed Languages . . . . . . 53
2.6.2 A Survey of Real Time Features Supported 55
2.6.3 A Discussion of Additional Real Time Features
Needed 59
2.6.4 Summary 63
2.7 Taking a Closer Look at Ada 64
2.7.1 Ada's Limitations 65
2.7.2 Changing Ada .. 66
2.8 Taking a Closer Look at PEARL 68
2.8.1 An Overview of Basic PEARL 68
2.8.2 PEARL's Limitations ..... 70
2.8.3 An Overview of Distributed PEARL 70
2.9 Proposal for an Extension of PEARL. 73
2.9.1 Locks and Timeouts .. 73
2.9.2 Timed Synchronisation 76
2.9.3 Time-Bounded Loops 78
x Constructing Predictable Real Time Systems
2.9.4 Status Operators .. . . . 78
2.9.5 Surveillance of Event Occurrences 79
2.9.6 Parallel Processing and Precedence Relations of
Tasks Sets. . . . 81
2.9.7 Expressing Timing Constraints 81
2.9.8 Overload Detection and Handling. 83
2.9.9 Hierarchical Deadlock Prevention. 84
2.9.10 Support of Task-Oriented Hierarchical Storage
Management .. 84
2.9.11 Exact Timing of Operations. 85
2.9.12 Tracing and Event Recording 86
2.9.13 Restriction to Static Language Features 86
2.9.14 Application-Oriented Simulation .. 86
2.9.15 Graceful System Degradation Using the Concept
of Imprecise Results . . 87
2.9.15.1 Transient Overloads 88
2.9.15.2 Diversity Based Error Detection and
Handling . . . . . . 90
2.9.16 Synopsis of PEARL Language Extensions 91
2.9.17 Summary 95
3 Language-Independent Schedulability Analysis of Real
Time Programs 97
3.1 Front End of the Schedulability Analyser 98
3.1.1 Front End Segment Trees . . . . . 99
3.1.2 Condition, Bracket, Subprogram and Process
Records . . . . . . . 104
3.1.3 Front End Statistics . 104
Contents Xl
3.2 Back End ofthe Schedulability Analyser. · 105
3.2.1 Resolving Segment Trees · 105
3.2.2 Converting Process Trees · 105
3.2.3 A Real Time Model ... · 108
3.2.3.1 A High Level Model Description . 109
3.2.3.2 A Survey of Real Time Modeling. . 110
3.2.3.3 Frame Superimposition - Our Solution
of the Model . 122
3.2.3.4 Delays.... . 130
3.2.3.5 Interruptible Slow-downs . 131
3.2.3.6 Overall Solution Algorithm . 132
3.3 Schedulability Analysis of Real-Time Euclid and Ex-
tended PEARL . 135
3.4 Summary . . . . 138
4 A Real Time Hardware Architecture 139
4.1 Useful Analogies . · 140
4.2 Properties and Architectural Implications ofComprehen-
sive Deadline-Driven Scheduling 142
4.2.1 Implications of Employing Earliest Deadline
Scheduling 147
4.2.2 Sufficient Conditionsfor FeasibleTask Executabil-
ity under Resource Constraints . . . . . 149
4.2.3 Non-pre-emptive Deadline Scheduling . 152
4.2.4 Avoiding Context-Switches Without Violation of
Feasibility 153
4.3 The Layered Structure of Real Time Operating Systems . 155
4.4 Outline ofthe Architecture 156
