Stage 2: Kernel Adventurer

Help learners understand how the Linux kernel manages processes, memory, and scheduling. Build confidence in explaining kernel concepts and demonstrate practical commands that reveal system internals - a frequent interview focus.

Hackbook Overview

• Kernel Role: Core of Linux, manages hardware, memory, processes, and system calls.
• Processes: Each running program is a process with PID (Process ID).
• Scheduling: Kernel decides which process runs and when (fairness, efficiency).
• Memory Management: Handles RAM allocation, swap space, and virtual memory.
• System Calls: Interface between user programs and kernel functions.
• Why It Matters: Interviewers test kernel knowledge to assess system‑level understanding.

Hands‑On Practice

• View running processes: ps aux or top.
• Kill a process: kill -9 <PID>.
• Check memory usage: free -h.
• View kernel version: uname -r.
• Inspect system calls: strace ls.

Interview Question Bank

Conceptual

• Q1. What is the role of the Linux kernel?
  A1. The kernel manages hardware, memory, processes, and system calls, acting as the bridge between applications and hardware.
• Q2. What is a process in Linux?
  A2. A process is an instance of a running program, identified by a unique PID.
• Q3. Explain Linux scheduling.
  A3. Scheduling determines which process runs at a given time, balancing fairness and efficiency using algorithms like CFS (Completely Fair Scheduler).

Practical

• Q4. How do you check memory usage in Linux?
  A4. Run free -h or use top to see RAM and swap usage.
• Q5. How do you find the kernel version?
  A5. Run uname -r.
• Q6. How do you trace system calls made by a command?
  A6. Use strace <command>. Example: strace ls.

Scenario‑Based

• Q7. A process is consuming too much CPU. How do you handle it?
  A7. Identify with top or ps aux, then terminate using kill -9 <PID>.
• Q8. The system is running out of memory. What steps would you take?
  A8. Check usage with free -h, identify heavy processes with top, and consider adding swap space.
• Q9. How would you explain virtual memory to a junior engineer?
  A9. Virtual memory allows processes to use more memory than physically available by mapping to disk (swap).

Behavioral Based

• Q10. Tell me about a time you solved a kernel or process issue.
  A10. Example: “I once resolved a server slowdown by identifying a runaway process with top and terminating it, restoring performance.”

Cheatsheet (Quick Notes)

• Kernel Role: Manages hardware, memory, processes.
• Processes: Identified by PID, managed with ps, kill.
• Scheduling: Determines process execution order.
• Memory: free -h, swap space, virtual memory.
• System Calls: Interface between apps and kernel (strace).