Operating System is a moderately hard subject. Most of the theory is logical, but numericals and problem-solving (scheduling, page replacement, disk algorithms) require practice. Understanding concepts is more important than rote memorization.

Chapter Importance & Difficulty:

OS Overview: Less important, easy – short-answer/conceptual questions.
Process Management: Very important, hard – highest marks (scheduling, IPC, classical problems).
Process Deadlocks: Important, medium – mainly theory and small numericals.
Memory Management: Very important, hard – medium-to-high marks (paging, segmentation, TLB, page replacement).
File Management: Less important, easy – short-answer type questions.
Device Management: Important, medium – disk scheduling, DMA, interrupts numericals.
Linux Case Study: Low importance, easy – mostly conceptual/short notes.

Approximate Revision Time:

3–4 days if focusing on numerical practice and key concepts.
7–8 hours for high-weight chapters (Process, Memory),
3–4 hours for medium-weight chapters (Deadlocks, Device Management),
2–3 hours for light chapters (File Management, OS Overview, Linux Case Study).