In order to thoroughly understand what makes Linux tick and why it works so well on a wide variety of systems, you need to delve deep into the heart of the kernel. The kernel handles all interactions between the CPU and the external world, and determines which programs will share processor time, in what order. It manages limited memory so well that hundreds of processes can share the system efficiently, and expertly organizes data transfers so that the CPU isn't kept waiting any longer than necessary for the relatively slow disks.

The third edition of Understanding the Linux Kernel takes you on a guided tour of the most significant data structures, algorithms, and programming tricks used in the kernel. Probing beyond superficial features, the authors offer valuable insights to people who want to know how things really work inside their machine. Important Intel-specific features are discussed. Relevant segments of code are dissected line by line. But the book covers more than just the functioning of the code; it explains the theoretical underpinnings of why Linux does things the way it does.

This edition of the book covers Version 2.6, which has seen significant changes to nearly every kernel subsystem, particularly in the areas of memory management and block devices. The book focuses on the following topics:

• Memory management, including file buffering, process swapping, and Direct memory Access (DMA)
• The Virtual Filesystem layer and the Second and Third Extended Filesystems
• Process creation and scheduling
• Signals, interrupts, and the essential interfaces to device drivers
• Timing
• Synchronization within the kernel
• Interprocess Communication (IPC)
• Program execution

Understanding the Linux Kernel will acquaint you with all the inner workings of Linux, but it's more than just an academic exercise. You'll learn what conditions bring out Linux's best performance, and you'll see how it meets the challenge of providing good system response during process scheduling, file access, and memory management in a wide variety of environments. This book will help you make the most of your Linux system.

为了彻底了解是什么让Linux运转起来，以及为什么它在各种系统上运转得这么好，你需要深入了解内核的核心。内核处理CPU和外部世界之间的所有互动，并决定哪些程序将分享处理器时间，以何种顺序。它能很好地管理有限的内存，使数以百计的程序能有效地共享系统，并能熟练地组织数据传输，使CPU在相对较慢的磁盘上的等待时间不会超过必要的时间。

第三版《理解Linux内核》将带领你参观内核中使用的最重要的数据结构、算法和编程技巧。作者超越了表面特征的探究，为那些想知道事情在他们的机器中如何真正工作的人提供了宝贵的见解。讨论了英特尔的重要特征。对相关的代码段进行了逐行剖析。但是，本书所涉及的不仅仅是代码的功能；它还解释了Linux为什么要这样做的理论基础。

本书的这一版本涵盖了2.6版本，几乎所有的内核子系统都发生了重大变化，特别是在内存管理和块设备领域。本书重点介绍了以下内容。

内存管理，包括文件缓冲、进程交换和直接内存访问（DMA）。

虚拟文件系统层以及第二和第三扩展文件系统

进程的创建和调度

信号、中断和设备驱动程序的基本接口

时间安排

内核内的同步化

进程间通信（IPC）

程序执行

了解Linux内核将使你熟悉Linux的所有内部运作，但它不仅仅是一个学术练习。你会了解到什么情况下能发挥出Linux的最佳性能，你会看到它是如何在各种环境下的进程调度、文件访问和内存管理中迎接挑战，提供良好的系统响应。本书将帮助你最大限度地利用你的Linux系统。