The new edition of "Understanding the Linux Kernel takes you on a guided tour through the most significant data structures, many algorithms, and programming tricks used in the kernel. Probing beyond the superficial features, the authors offer valuable insights to people who want to know how things really work inside their machine. Relevant segments of code are dissected and discussed line by line. The book covers more than just the functioning of the code, it explains the theoretical underpinnings for why Linux does things the way it does. The new edition of the book has been updated to cover version 2.4 of the kernel, which is quite different from version 2.2: the virtual memory system is entirely new, support for multiprocessor systems is improved, and whole new classes of hardware devices have been added. You'll learn what conditions bring out Linux's best performance, and how it meets the challenge of providing good system response during process scheduling, file access, and memory managementin a wide variety of environments. If knowledge is power, then this book will help you make the most of your Linux system.

Preface

ix

Introduction

1

(33)

Linux Versus Other Unix-Like Kernels

2

(4)

Hardware Dependency

6

(1)

Linux Versions

7

(1)

Basic Operating System Concepts

8

(4)

An Overview of the Unix Filesystem

12

(6)

An Overview of Unix Kernels

18

(16)

Memory Addressing

34

(38)

Memory Addresses

34

(1)

Segmentation in Hardware

35

(5)

Segmentation in Linux

40

(4)

Paging in Hardware

44

(10)

Paging in Linux

54

(18)

Processes

72

(37)

Processes, Lightweight Processes, and Threads

72

(2)

Process Descriptor

74

(15)

Process Switch

89

(10)

Creating Processes

99

(7)

Destroying Processes

106

(3)

Interrupts and Exceptions

109

(52)

The Role of Interrupt Signals

110

(1)

Interrupts and Exceptions

111

(10)

Nested Execution of Exception and Interrupt Handlers

121

(1)

Initializing the Interrupt Descriptor Table

122

(3)

Exception Handling

125

(3)

Interrupt Handling

128

(17)

Softirqs, Tasklets, and Bottom Halves

145

(11)

Returning from Interrupts and Exceptions

156

(5)

Kernel Synchronization

161

(32)

Kernel Control Paths

161

(1)

When Synchronization Is Not Necessary

162

(1)

Synchronization Primitives

163

(21)

Synchronizing Accesses to Kernel Data Structures

184

(5)

Examples of Race Condition Prevention

189

(4)

Timing Measurements

193

(24)

Hardware Clocks

194

(3)

The Linux Timekeeping Architecture

197

(5)

CPU's Time Sharing

202

(1)

Updating the Time and Date

203

(1)

Updating System Statistics

204

(2)

Software Timers

206

(7)

System Calls Related to Timing Measurements

213

(4)

Memory Management

217

(46)

Page Frame Management

217

(22)

Memory Area Management

239

(17)

Noncontiguous Memory Area Management

256

(7)

Process Address Space

263

(40)

The Process's Address Space

264

(1)

The Memory Descriptor

265

(3)

Memory Regions

268

(17)

Page Fault Exception Handler

285

(13)

Creating and Deleting a Process Address Space

298

(2)

Managing the Heap

300

(3)

System Calls

303

(15)

POSIX APIs and System Calls

303

(1)

System Call Handler and Service Routines

304

(12)

Kernel Wrapper Routines

316

(2)

Signals

318

(30)

The Role of Signals

318

(9)

Generating a Signal

327

(5)

Delivering a Signal

332

(11)

System Calls Related to Signal Handling

343

(5)

Process Scheduling

348

(24)

Scheduling Policy

348

(4)

The Scheduling Algorithm

352

(15)

System Calls Related to Scheduling

367

(5)

The Virtual Filesystem

372

(55)

The Role of the Virtual Filesystem (VFS)

372

(6)

VFS Data Structures

378

(16)

Filesystem Types

394

(3)

Filesystem Mounting

397

(10)

Pathname Lookup

407

(9)

Implementations of VFS System Calls

416

(4)

File Locking

420

(7)

Managing I/O Devices

427

(47)

I/O Architecture

427

(10)

Device Files

437

(4)

Device Drivers

441

(8)

Block Device Drivers

449

(22)

Character Device Drivers

471

(3)

Disk Caches

474

(23)

The Page Cache

476

(5)

The Buffer Cache

481

(16)

Accessing Files

497

(31)

Reading and Writing a File

497

(16)

Memory Mapping

513

(10)

Direct I/O Transfers

523

(5)

Swapping: Methods for Freeing Memory

528

(46)

What Is Swapping?

529

(2)

Swap Area

531

(14)

The Swap Cache

545

(3)

Transferring Swap Pages

548

(3)

Swapping Out Pages

551

(5)

Swapping in Pages

556

(3)

Reclaiming Page Frame

559

(15)

The Ext2 and Ext3 Filesystems

574

(34)

General Characteristics of Ext2

574

(3)

Ext2 Disk Data Structures

577

(7)

Ext2 Memory Data Structures

584

(4)

Creating the Ext2 Filesystem

588

(2)

Ext2 Methods

590

(2)

Managing Ext2 Disk Space

592

(8)

The Ext3 Filesystem

600

(8)

Networking

608

(24)

Main Networking Data Structures

609

(9)

System Calls Related to Networking

618

(9)

Sending Packets to the Network Card

627

(2)

Receiving Packets from the Network Card

629

(3)

Process Communication

632

(29)

Pipes

633

(9)

FIFOs

642

(2)

System V IPC

644

(17)

Program Execution

661

(24)

Executable Files

662

(12)

Executable Formats

674

(2)

Execution Domains

676

(2)

The exec Functions

678

(7)

A. System Startup

685

(7)

B. Modules

692

(10)

C. Source Code Structure

702

(5)

Bibliography

707

(4)

Source Code Index

711

(38)

Index

749

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