Operating Systems Study Notes

Classical Synchronization Problems

Study the Producer-Consumer, Readers-Writers, and Dining Philosophers problems and their semaphore-based solutions.

Common OS Pitfalls

The most frequent conceptual mistakes students make about operating systems, with corrections.

Context Switching

Understand what happens when the CPU switches between processes and why it is pure overhead.

Contiguous Memory Allocation

Allocating each process a single unbroken block of physical memory, and the fragmentation problems that follow.

Deadlock Conditions

The four necessary conditions (Coffman conditions) that must hold simultaneously for a deadlock to occur.

Deadlock Detection and Recovery

Letting deadlocks occur, detecting them via cycle/graph algorithms, and recovering through termination or preemption.

Deadlock Prevention and Avoidance

How to stop deadlocks before they happen: prevention breaks a Coffman condition; avoidance uses the Banker's Algorithm.

Demand Paging

Lazy loading of pages into memory only when referenced, and the step-by-step page-fault handling sequence that makes it work.

Directory Structures

How file systems organize files into single-level, two-level, tree, and acyclic-graph directory hierarchies.

Disk Scheduling Algorithms

How the OS orders pending disk I/O requests to minimize head movement, comparing FCFS, SSTF, and SCAN.

FCFS and SJF Scheduling

First-Come-First-Served and Shortest-Job-First scheduling, worked through Gantt charts with exact waiting/turnaround-time math.

File Allocation Methods

How the operating system maps a file's logical blocks onto physical disk blocks: contiguous, linked, and indexed allocation.

File System Basics

How an operating system organizes, names, and provides access to persistent data on secondary storage.

Interprocess Communication

How independent processes with separate address spaces exchange data and coordinate using OS-provided IPC mechanisms.

Introduction to Deadlocks

Get a high-level preview of what deadlock is and the four necessary conditions that must all hold for it to occur.

Introduction to Operating Systems

Learn what an operating system is, why it exists, and how it mediates between hardware and applications.

Memory Management Basics

How an OS tracks, allocates, and protects the memory used by processes running on a system.

Monitors

Learn how monitors bundle shared data, procedures, and condition variables into a higher-level synchronization construct.

Multilevel Queue Scheduling

How fixed-priority multilevel queues differ from adaptive multilevel feedback queues, and how each handles process movement.

Mutex and Semaphores

Compare mutexes and binary/counting semaphores as tools for enforcing mutual exclusion and coordinating threads.

OS Design Tradeoffs

A grounded look at the core engineering tradeoffs behind major operating system design decisions.

OS Functions and Types

Explore the core functions every OS performs and the major categories of operating systems.

Common OS Interview Questions

The most frequently asked operating systems interview questions with clear, technically accurate answers.

OS Quick Reference

A consolidated reference summary of the core operating systems concepts, metrics, and algorithms covered in this course.