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)
Section 1: The Basics
Writing Your First Kernel Module - LKMs Part 2
Section 2: Understanding and Working with the Kernel
Kernel Memory Allocation for Module Authors - Part 1
Kernel Memory Allocation for Module Authors - Part 2
Section 3: Delving Deeper
About Packt

Viewing the results

We carry out a similar procedure for the remaining two test cases and summarize the results of all three in Figure 11.14:

Figure 11.14 – Results of the (simplistic) test cases we ran showing the min/avg/max latencies for different kernels and systems while under some stress

Interesting; though the maximum latency of the RTL kernel is much below the other standard kernels, both the minimum and, more importantly, average latencies are superior for the standard kernels. This ultimately results in superior overall throughput for the standard kernels (this very same point was stressed upon earlier).

The bash script invokes the gnuplot(1) utility to generate graphs, in such a manner that the title line shows the minimum/average/maximum latency values (in microseconds) and the kernel the test was run upon. Recollect that test case #1 and #2 ran on the Raspberry Pi 3B+ device, whereas test case #3 ran on a generic...