Book Image

Mastering Linux Kernel Development

By : CH Raghav Maruthi
Book Image

Mastering Linux Kernel Development

By: CH Raghav Maruthi

Overview of this book

Mastering Linux Kernel Development looks at the Linux kernel, its internal arrangement and design, and various core subsystems, helping you to gain significant understanding of this open source marvel. You will look at how the Linux kernel, which possesses a kind of collective intelligence thanks to its scores of contributors, remains so elegant owing to its great design. This book also looks at all the key kernel code, core data structures, functions, and macros, giving you a comprehensive foundation of the implementation details of the kernel’s core services and mechanisms. You will also look at the Linux kernel as well-designed software, which gives us insights into software design in general that are easily scalable yet fundamentally strong and safe. By the end of this book, you will have considerable understanding of and appreciation for the Linux kernel.
Table of Contents (12 chapters)

Runqueue


Conventionally, the runqueue contains all the processes that are contending for CPU time on a given CPU core (a runqueue is per-CPU). The generic scheduler is designed to look into the runqueue whenever it is invoked to schedule the next best runnable task. Maintaining a common runqueue for all the runnable processes would not be a possible since each scheduling class deals with specific scheduling policies and priorities.

The kernel addresses this by bringing its design principles to the fore. Each scheduling class defined the layout of its runqueue data structure as best suitable for its policies. The generic scheduler layer implements an abstract runqueue structure with common elements that serves as the runqueue interface. This structure is extended with pointers that refer to class-specific runqueues. In other words, all scheduling classes embed their runqueues into the main runqueue structure. This is a classic design hack, which lets every scheduler class choose an appropriate...