Book Image

Linux Kernel Programming

By : Kaiwan N. Billimoria
Book Image

Linux Kernel Programming

By: Kaiwan N. Billimoria

Overview of this book

Linux Kernel Programming is a comprehensive introduction for those new to Linux kernel and module development. This easy-to-follow guide will have you up and running with writing kernel code in next-to-no time. This book uses the latest 5.4 Long-Term Support (LTS) Linux kernel, which will be maintained from November 2019 through to December 2025. By working with the 5.4 LTS kernel throughout the book, you can be confident that your knowledge will continue to be valid for years to come. You’ll start the journey by learning how to build the kernel from the source. Next, you’ll write your first kernel module using the powerful Loadable Kernel Module (LKM) framework. The following chapters will cover key kernel internals topics including Linux kernel architecture, memory management, and CPU scheduling. During the course of this book, you’ll delve into the fairly complex topic of concurrency within the kernel, understand the issues it can cause, and learn how they can be addressed with various locking technologies (mutexes, spinlocks, atomic, and refcount operators). You’ll also benefit from more advanced material on cache effects, a primer on lock-free techniques within the kernel, deadlock avoidance (with lockdep), and kernel lock debugging techniques. By the end of this kernel book, you’ll have a detailed understanding of the fundamentals of writing Linux kernel module code for real-world projects and products.
Table of Contents (19 chapters)
1
Section 1: The Basics
6
Writing Your First Kernel Module - LKMs Part 2
7
Section 2: Understanding and Working with the Kernel
10
Kernel Memory Allocation for Module Authors - Part 1
11
Kernel Memory Allocation for Module Authors - Part 2
14
Section 3: Delving Deeper
17
About Packt

Summary

In this, our second chapter on CPU scheduling on the Linux OS, you have learned several key things. Among them, you learned how to visualize kernel flow with powerful tools such as LTTng and the Trace Compass GUI, as well as with the trace-cmd(1) utility, a convenient frontend to the kernel's powerful Ftrace framework. You then saw how to programatically query and set any thread's CPU affinity mask. This naturally led to a discussion on how you can programmatically query and set any thread's scheduling policy and priority. The whole notion of being "completely fair" (via the CFS implementation) was brought into question, and some light was shed on the elegant solution called cgroups. You even learned how to leverage the cgroups v2 CPU controller to allocate CPU bandwidth as desired to processes in a sub-group. We then understood that though Linux is a GPOS, an RTL patchset very much exists, which, once applied and the kernel is configured and...