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 (19 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback

Completely Fair Scheduling class (CFS)

All processes with dynamic priorities are handled by the CFS class, and as most processes in general-purpose *nix systems are normal (non-realtime), CFS remains the busiest scheduler class in the kernel.

CFS relies on maintaining balance in allocating processor time to tasks, based on policies and dynamic priorities assigned per task. Process scheduling under CFS is implemented under the premise that it has an "ideal, precise multi-tasking CPU," that equally powers all processes at its peak capacity. For instance, if there are two processes, the perfectly multi-tasking CPU ensures that both processes run simultaneously, each utilizing 50% of its power. As this is practically impossible (achieving parallelism), CFS allocates processor time to a process by maintaining proper balance across all contending processes. If a process fails to receive a fair amount of time, it is considered out of balance, and thus goes in next as the best runnable process.