Interview Questions from OS which does a regular round in campus recruitment.

1. What do the system calls fork(), vfork(), exec(), wait(), waitpid() do? Whats a Zombie process? Whats the difference between fork() and vfork()?


2. How does freopen() work?


3. What are threads? What is a lightweight process? What is a heavyweight process? How different is a thread from a process?


4. How are signals handled?


5. What is a deadlock?


6. What are semaphores?


7. What is meant by context switching in an OS?


8. What is Belady's anomaly?


9. What is thrashing?


10. What are short-, long- and medium-term scheduling?


11. What are turnaround time and response time?


12. What is the Translation Lookaside Buffer (TLB)?


13. What is cycle stealing?


14. What is a reentrant program?


15. When is a system in safe state?


16. What is busy waiting?


17. What is pages replacement? What are local and global page replacements?


18. What is meant by latency, transfer and seek time with respect to disk I/O?


19. What are monitors? How are they different from semaphores?


20. In the context of memory management, what are placement and replacement algorithms?


21. What is paging? What are demand- and pre-paging?


22. What is mounting?


23. What do you mean by dispatch latency?


24. What is multi-processing? What is multi-tasking? What is multi-threading?


25. What is multi-programming?


26. What is compaction?


27. What is memory-mapped I/O? How is it different frim I/O mapped I/O?


28. List out some reasons for process termination.