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

Measuring scheduling latency with cyclictest

To make this more interesting (as well as to run the latency test on a constrained system), we shall perform latency measurements using the well-known cyclictest app – while the system is under some amount of load (via the stress(1) utility) – on the equally well-known Raspberry Pi device. This section is divided into four logical parts:

  1. First, set up the working environment on the Raspberry Pi device.
  2. Second, download and apply the RT patches on the kernel source, configure, and build it.
  1. Third, install the cyclictest app, as well as a few other required packages (including stress), on the device.
  2. Fourth, run the test cases and analyze the results (even plotting graphs to help do so).

The first step and most parts of the second have already been covered in detail in Chapter 3, Building the 5.x Linux Kernel from Source – Part 2, in the Kernel build for the Raspberry Pi section. This includes...