Table Of ContentUndergraduate Topics in Computer Science
Undergraduate Topics in Computer Science (UTiCS) delivers high-quality instructional content for
undergraduatesstudyinginallareasofcomputingandinformationscience.Fromcorefoundationaland
theoreticalmaterialtofinal-yeartopicsandapplications,UTiCSbookstakeafresh,concise,andmodern
approachandareidealforself-studyorforaone-ortwo-semestercourse.Thetextsareallauthoredby
establishedexpertsintheirfields,reviewedbyaninternationaladvisoryboard,andcontainnumerous
examplesandproblems.Manyincludefullyworkedsolutions.
Alsointhisseries
IainD.Craig
Object-OrientedProgrammingLanguages:Interpretation
978-1-84628-773-2
MaxBramer
PrinciplesofDataMining
978-1-84628-765-7
HanneRiisNielsonandFlemmingNielson
SemanticswithApplications:AnAppetizer
978-1-84628-691-9
Michael Kifer and Scott A. Smolka
Introduction
to Operating
System Design
and Implementation
The OSP 2 Approach
MichaelKifer,PhD ScottA.Smolka,PhD
StateUniversityofNewYork StateUniversityofNewYork
atStonyBrook,NY,USA atStonyBrook,NY,USA
Serieseditor
IanMackie
ÉcolePolytechnique,FranceandKing’sCollegeLondon,UK
Advisoryboard
SamsonAbramsky,UniversityofOxford,UK
ChrisHankin,ImperialCollegeLondon,UK
DexterKozen,CornellUniversity,USA
AndrewPitts,UniversityofCambridge,UK
HanneRiisNielson,TechnicalUniversityofDenmark,Denmark
StevenSkiena,StonyBrookUniversity,USA
IainStewart,UniversityofDurham,UK
DavidZhang,TheHongKongPolytechnicUniversity,HongKong
BritishLibraryCataloguinginPublicationData
AcataloguerecordforthisbookisavailablefromtheBritishLibrary
LibraryofCongressControlNumber:2007926598
UndergraduateTopicsinComputerScienceISSN1863-7310
ISBN978-1-84628-842-5 e-ISBN978-1-84628-843-2
Printedonacid-freepaper
c Springer-VerlagLondonLimited2007
⃝
Apartfromanyfairdealingforthepurposesofresearchorprivatestudy,orcriticismorreview,as
permittedundertheCopyright,DesignsandPatentsAct1988,thispublicationmayonlybereproduced,
storedortransmitted,inanyformorbyanymeans,withthepriorpermissioninwritingofthe
publishers,orinthecaseofreprographicreproductioninaccordancewiththetermsoflicencesissued
bytheCopyrightLicensingAgency.Enquiriesconcerningreproductionoutsidethosetermsshouldbe
senttothepublishers.
Theuseofregisterednames,trademarks,etc.inthispublicationdoesnotimply,evenintheabsenceofa
specificstatement,thatsuchnamesareexemptfromtherelevantlawsandregulationsandthereforefree
forgeneraluse.
Thepublishermakesnorepresentation,expressorimplied,withregardtotheaccuracyofthe
informationcontainedinthisbookandcannotacceptanylegalresponsibilityorliabilityforanyerrors
oromissionsthatmaybemade.
987654321
SpringerScience+BusinessMedia
springer.com
Contents
Preface ......................................................... ix
1. Organization of 2 ..................................... 1
OSP
1.1 Chapter Objective........................................ 1
1.2 Operating System Basics .................................. 1
1.3 2 Organization ..................................... 6
OSP
1.4 Simulated Hardware in 2 ............................. 8
OSP
1.5 Utilities ................................................. 11
1.6 2 Events ........................................... 16
OSP
1.7 2 Daemons ......................................... 18
OSP
1.8 Compiling and Running Projects ........................... 19
1.9 General Rules of Engagement .............................. 24
1.9.1 A Day in the Life of an 2 Thread................ 25
OSP
1.9.2 Convention for Calling Student Methods .............. 26
1.9.3 Static vs. Instance Methods.......................... 28
1.9.4 Obfuscation of Method and Class Names .............. 28
1.9.5 Possible Hanging After Errors........................ 29
1.9.6 Possible Exceptions After the End of Execution ........ 29
1.9.7 General Advice: How to Figure it Out ................ 29
1.10 System Log, Snapshots, and Statistics....................... 30
1.11 Debugging............................................... 31
1.12 Project Submission ....................................... 35
2. Putting it All Together: An Example Session with 2 .. 39
OSP
2.1 Chapter Objective........................................ 39
2.2 Overview of Thread Management in 2 ................. 39
OSP
vi Introduction to OperatingSystemDesign and Implementation:The 2 Approach
OSP
2.3 The Student Method do resume().......................... 40
2.4 Step 1: Compiling and Running the Project.................. 41
2.5 Step 2: Examining the OSP.log File ........................ 42
2.6 Step 3: Introducing an Error into do resume()............... 43
3. Tasks: Management of Tasks (a.k.a. Processes) ............. 45
3.1 Chapter Objective........................................ 45
3.2 Conceptual Background ................................... 45
3.3 Class TaskCB ............................................ 46
3.4 Methods Exported by the Tasks Package ................... 53
4. Threads: Management and Scheduling of Threads .......... 57
4.1 Chapter Objective........................................ 57
4.2 Overview of Threads...................................... 57
4.3 The Class ThreadCB ...................................... 61
4.4 The Class TimerInterruptHandler......................... 71
4.5 Methods Exported by the Threads Package................. 72
5. Memory: Virtual Memory Management..................... 75
5.1 Chapter Objective........................................ 75
5.2 Overview of Memory Management.......................... 75
5.3 Class FrameTableEntry................................... 83
5.4 Class PageTableEntry .................................... 86
5.5 Class PageTable ......................................... 90
5.6 Class MMU................................................ 91
5.7 Class PageFaultHandler.................................. 95
5.8 Methods Exported by Package Memory ....................100
6. Devices: Scheduling of Disk Requests.......................103
6.1 Chapter Objective........................................103
6.2 Overview of I/O Handling .................................103
6.3 Class IORB...............................................106
6.4 Class Device ............................................109
6.5 Class DiskInterruptHandler..............................114
6.6 Methods Exported by Package Devices.....................117
7. FileSys: The File System ...................................119
7.1 Chapter Objective........................................119
7.2 File System Design Objectives .............................119
7.3 Overview of the 2 File System ........................121
OSP
7.4 Class MountTable ........................................123
7.5 Class INode..............................................127
Contents vii
7.6 Class DirectoryEntry ....................................129
7.7 Class OpenFile ..........................................131
7.8 Class FileSys ...........................................136
7.9 Methods Exported by the FileSys Package..................141
8. Ports: Interprocess Communication ........................143
8.1 Chapter Objective........................................143
8.2 Interprocess Communication in 2 ......................143
OSP
8.3 The MessageClass .......................................144
8.4 The PortCB Class ........................................146
8.5 Methods Exported by PackagePorts.......................151
9. Resources: Resource Management..........................153
9.1 Chapter Objective........................................153
9.2 Overview of Resource Management .........................153
9.3 Overview of Resource Management in 2 ................155
OSP
9.4 Class ResourceTable .....................................156
9.5 Class RRB................................................157
9.6 Class ResourceCB ........................................160
9.7 Methods Exported by the Resources Package...............166
Index...........................................................167
Preface
2 is bothanimplementationofamodernoperatingsystem,andaflexible
OSP
environment for generating implementation projects appropriate for an intro-
ductory course in operating system design. It is intended to complement the
use of an introductory textbook on operating systems and contains enough
projects for up to three semesters. These projects expose students to many
essential features of operating systems, while at the same time isolating them
from low-level machine-dependent concerns. Thus, even in one semester, stu-
dents can learn about page replacement strategies in virtual memory manage-
ment, cpu scheduling strategies, disk seek time optimization, and other issues
in operating system design.
2 is written in the Java programminglanguage and students program
OSP
their 2 projectsinJavaaswell.Thereforeasprerequisitesforusing 2,
OSP OSP
students are expected to have solid Java programming skills; be well-versed in
object-oriented programming concepts such as classes, objects, methods, and
inheritance; to have taken an undergraduate Computer Science course in data
structures;andtohaveworkingknowledgeofaJavaprogrammingenvironment,
i.e., javac,java,text editing, etc. 2 is the successorto the original
OSP OSP
software, which was released in 1990 and programmedin C.
2 consists of a number of modules, each of which performs a basic
OSP
operating systems service, such as device scheduling, cpu scheduling, inter-
rupt handling, file management, memory management, process management,
resource management, and interprocess communication. Projects can be orga-
nized in any desired order so as to progress in a manner consistent with the
lecture material. The 2 distribution comes with a reference Java imple-
OSP
mentation of each module, which is provided to the course instructor.
Each 2 project has a well-defined API (application programming in-
OSP
terface), that the student must implement in order to successfully complete
x Introduction toOperating SystemDesign andImplementation:The 2 Approach
OSP
the project. Thus, among other things, 2 teaches students to work with
OSP
“open” environments where programming must be conducted to satisfy con-
cretesets ofprojectrequirementsandwhere APIsmustbe usedtointerface to
other subsystems.
Each 2 project consists of a “partialloadmodule” of standard 2
OSP OSP
modules to which the students link their implementation of the assigned mod-
ules.Theresultisanewandcompleteoperatingsystem,partiallyimplemented
by the student. Additionally, each project includes one or more “*.java” files,
which contain class and method headings for each of the assigned modules.
These files serve as templates in which the student is to fill in the code for the
requiredmethods. This ensures a consistent interface to 2 and eliminates
OSP
much of the routine typing, both by the instructor and by the student.
The heart of 2 is a simulator that gives the illusion of a computer
OSP
systemwithadynamicallyevolvingcollectionofuserprocessestobemultipro-
grammed. All the other modules of 2 are built to respond appropriately
OSP
to the simulator-generated events that drive the operating system. The simu-
lator “understands” its interactionwith the other modules in that it can often
detect an erroneous response by a module to a simulated event. In such cases,
the simulator will gracefully terminate execution of the program by delivering
a meaningful error message to the user, indicating where the error might be
found. This facility serves both as a debugging tool for the student and as
teachingtoolforthe instructor,asitensuresthatstudentprogramsacceptable
to the simulatorarevirtuallybug-free.(Verificationbythe simulatordoesnot,
ofcourse,replacetheneedtoexaminestudentprogramstoensurethattheyare
properly designed and acceptable from a software engineering point of view.)
The difficulty of the job streams generated by the simulator can be dy-
namically adjusted by manipulating the simulation parameters. This yields a
simple and effective way of testing the quality of student programs. There are
alsofacilities thatallowstudents to debug theirprograms,including adetailed
system log of events and various hooks into the system that allow student-
provided methods to be called when an 2 warning or error is detected.
OSP
Also, a graphical user interface (GUI) is available that provides a convenient
way for students and instructors to enter simulation parameters and to view
various statistics concerning the execution of 2.
OSP
The underlying model in 2 is not a clone of any specific operating
OSP
system. Rather it is an abstraction of the common features of several systems
(although a bias towards Unix and the Mach operating systems can be seen,
at times). Moreover, the 2 modules were designed to hide a number of
OSP
low-levelconcerns,yetstillencompassthe mostsalientaspectsoftheirreal-life
counterparts in modern systems. Their implementation is well-suited as the
project component of an introductory course in operating systems.
