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Mastering Embedded Linux Programming

You're reading from   Mastering Embedded Linux Programming Create fast and reliable embedded solutions with Linux 5.4 and the Yocto Project 3.1 (Dunfell)

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Product type Paperback
Published in May 2021
Publisher Packt
ISBN-13 9781789530384
Length 758 pages
Edition 3rd Edition
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Authors (2):
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Frank Vasquez Frank Vasquez
Author Profile Icon Frank Vasquez
Frank Vasquez
Mr. Chris Simmonds Mr. Chris Simmonds
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Mr. Chris Simmonds
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Table of Contents (27) Chapters Close

Preface 1. Section 1: Elements of Embedded Linux
2. Chapter 1: Starting Out FREE CHAPTER 3. Chapter 2: Learning about Toolchains 4. Chapter 3: All about Bootloaders 5. Chapter 4: Configuring and Building the Kernel 6. Chapter 5: Building a Root Filesystem 7. Chapter 6: Selecting a Build System 8. Chapter 7: Developing with Yocto 9. Chapter 8: Yocto Under the Hood 10. Section 2: System Architecture and Design Decisions
11. Chapter 9: Creating a Storage Strategy 12. Chapter 10: Updating Software in the Field 13. Chapter 11: Interfacing with Device Drivers 14. Chapter 12: Prototyping with Breakout Boards 15. Chapter 13: Starting Up – The init Program 16. Chapter 14: Starting with BusyBox runit 17. Chapter 15: Managing Power 18. Section 3: Writing Embedded Applications
19. Chapter 16: Packaging Python 20. Chapter 17: Learning about Processes and Threads 21. Chapter 18: Managing Memory 22. Section 4: Debugging and Optimizing Performance
23. Chapter 19: Debugging with GDB 24. Chapter 20: Profiling and Tracing 25. Chapter 21: Real-Time Programming 26. Other Books You May Enjoy

Scheduling

The second big topic I want to cover in this chapter is scheduling. The Linux scheduler has a queue of threads that are ready to run, and its job is to schedule them on CPUs as they become available. Each thread has a scheduling policy that may be time-shared or real-time. The time-shared threads have a niceness value that increases or reduces their entitlement to CPU time. The real-time threads have priority in that a higher priority thread will preempt a lower one. The scheduler works with threads, not processes. Each thread is scheduled regardless of which process it is running in.

The scheduler runs when any of the following occurs:

  • A thread is blocked by calling sleep() or another blocking system call
  • A time-shared thread exhausts its time slice
  • An interruption causes a thread to be unblocked, for example, because of
    I/O completing

For background information on the Linux scheduler, I recommend that you read the chapter on process scheduling...

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