The Linux kernel is the foundation of modern computing, powering everything from embedded devices to supercomputers. Unlike user-space applications, which operate within an abstracted runtime environment, the kernel directly manages hardware resources, enforces security policies, and provides critical system services.

For engineers, researchers, and system architects, a deep understanding of the Linux kernel enables:

• Optimized Performance: Fine-tuning CPU scheduling, memory allocation, and I/O operations.
• System Customization: Developing kernel modules, modifying existing subsystems, and implementing new security policies.
• Debugging and Profiling: Identifying bottlenecks and diagnosing system crashes at the lowest levels.
• Security Hardening: Understanding privilege separation, syscall filtering, and exploit mitigation techniques.

This guide provides a structured roadmap to mastering the Linux kernel, focusing on its core subsystems. Each section presents key technical questions to explore and hands-on projects that reinforce practical skills. By working through these topics, you will develop a systems-level mindset, enabling you to contribute to the kernel, optimize system performance, and build more robust software.

Index

Process Management & Scheduling

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• ❓ How does the Linux scheduler choose which process to run?
• ❓ What are the differences between CFS (Completely Fair Scheduler) and real-time scheduling policies?
• ❓ How does fork() work at the kernel level?
• ❓ How do kernel threads (kthread) differ from user-space threads?
• ✅ Write a simple kernel module that creates and manages a kernel thread.
• ✅ Modify the CFS scheduler to log scheduling decisions.
• ✅ Implement a simple syscall that returns process scheduling statistics.

Memory Management