How the spinlock is implemented is really not our concern here; the fact that the spinlock has a lower overhead than the mutex lock is of interest to us. How so? It's simple, really: for the mutex lock to work, the loser thread has to go to sleep. To do so, internally, the schedule() function gets called, which means the loser sees the mutex lock API as a blocking call! A call to the scheduler will ultimately result in the processer being context-switched off. Conversely, when the owner thread unlocks the lock, the loser thread(s) must be woken up; again, it will be context-switched back onto the processor. Thus, the minimal "cost" of the mutex lock/unlock operation is the time it takes to perform two context switches on the given machine. (See the Information Box in the next section.) By relooking at the preceding screenshot once more, we can determine a few things, including...
Linux Kernel Programming
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Linux Kernel Programming
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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.
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Current Title:
Linux Kernel Programming
Table of Contents (19 chapters)
Preface
Section 1: The Basics
Free Chapter
Kernel Workspace Setup
Building the 5.x Linux Kernel from Source - Part 1
Building the 5.x Linux Kernel from Source - Part 2
Writing Your First Kernel Module - LKMs Part 1
Writing Your First Kernel Module - LKMs Part 2
Section 2: Understanding and Working with the Kernel
Kernel Internals Essentials - Processes and Threads
Memory Management Internals - Essentials
Kernel Memory Allocation for Module Authors - Part 1
Kernel Memory Allocation for Module Authors - Part 2
The CPU Scheduler - Part 1
The CPU Scheduler - Part 2
Section 3: Delving Deeper
Kernel Synchronization - Part 1
Kernel Synchronization - Part 2
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