Anna University - OPERATING SYSTEMS (OS)–Question Bank 2012 Edition

Anna University

Department of Computer Science and Engineering




Sub Code/Name: CS2254/Operating Systems

Class:II CSE



Part - A

1. What is an operating system?

2. What is the kernel?

3. What are batch systems?

4. Differentiate tightly coupled systems and loosely coupled systems.

6. What is real time system?

8. What do you mean by system calls?

10. What is a process?

11. What is process control block?

12. What is scheduler?

13. What are the use of job queues, ready queues and device queues?

14. What is meant by context switch?

15. What is independent process?

16. What is co-operative process?

17. What are the benefits OS co-operating processes?

19. State the advantage of multiprocessor system.

20. What is the use of inter process communication?

22. What are the benefits of multithreaded programming?

23. Compare user threads and kernel threads.

24. What is the use of fork and exec system calls?

Part - B

1. Explain the various types of computer systems.

2. (i) what is the purpose of system calls? Briefly explain the types of system calls provided by a typical operating system.

(ii)Explain how co-operating process communication with each other via an IPC.

3. Discuss briefly the various issues involved in implementing Inter process communication (IPC) in message passing system.

4. Explain in detail about the threading issues.

5. Explain about Multi-Threading Models.

6. Explain in detail about Review of Computer Organization.

7. Write short notes about Process concept and process scheduling.



1. Define CPU scheduling.

2. What is preemptive and no preemptive scheduling?

3. What is a Dispatcher?

4. What is dispatch latency?

5. What are the various scheduling criteria for CPU scheduling?

6. Define throughput.

7. What is turnaround time?

8. Define race condition.

9. What is critical section problem?

10. What are the requirements that a solution to the critical section problem must satisfy?

11. Define entry section and exit section.

12. What is a semaphore?

13. Define busy waiting and spin lock.

14. Define deadlock.

15. What are conditions under which a deadlock situation may arise?

16. What is a resource-allocation graph?

17. Define request edge and assignment edge.

18. What are the methods for handling deadlocks?

19. Define deadlock prevention.

20. Define deadlock avoidance.

21. What are a safe state and an unsafe state?

22. What is banker’s algorithm?

Part - B

1. Write about the various CPU scheduling algorithms.

2. What is critical section problem and explain two process solutions and multiple process solutions?

3. Explain what semaphores are, their usage, implementation given to avoid busy waiting and binary semaphores.

4. Write about critical regions and monitors.

5. Give a detailed description about deadlocks and its characterization.

6. Explain about the methods used to prevent deadlocks

7.Explain the Banker’s algorithm for deadlock avoidance.

8. Consider the following snapshot of a system:

Process Allocation max available


Answer the following questions using the banker’s algorithm:

1) What is the content of the matrix need?

2) Is the system in a safe state?

3) If a request from process p1 arrives for (0, 4, 2, 0), can the request be granted immediately?

9. Consider the following set of process, with the length of the CPU-burst time given in milliseconds:

process   Burst time      Priority

P1                  10              3

P2                     1            1

P3                    2            3

P4                   1            4

P5                   5            2

The processes are assumed to have arrived in the order p1, p2, p3, p4, p5, all at time 0.

a) Draw four Gantt charts illustrating the execution of these process using FCFS, SJF, a nonpreemptive priority (a smaller priority number implies a higher priority), and RR (quantum=1) scheduling.

b) What is the turnaround time of each process for each of the scheduling algorithms in part a?

c) What is the waiting time of each process for each of the scheduling algorithms in part a?

d) Which of the schedules in part a results in the minimal average waiting time (over all processes)?


1. Define logical address and physical address.

2. What is logical address space and physical address space?

3. What is the main function of the memory-management unit?

4. Define dynamic loading.

5. Define dynamic linking.

6. Define swapping.

7. What are the common strategies to select a free hole from a set of available holes?

8. What do you mean by best fit?

9. What do you mean by first fit?

10. What is virtual memory?

11. What is Demand paging?

12. Define lazy swapper.

13. What is a pure demand paging?

14. Define effective access time.

15. Define secondary memory.

16. What is the basic approach of page replacement?

17. What are the various page replacement algorithms used for page replacement?

18. What are the major problems to implement demand paging?

19. What is a reference string?

20. What are the advantages of Contiguous allocation?

21. Define Paging.

22. Define Segmentation.

Part - B

1. Explain about contiguous memory allocation.

2. Give the basic concepts about paging.

3. Explain the basic concepts of segmentation.

4. Explain the various page replacement strategies.

5. Consider the following page-reference string:


How many page faults would occur for the following replacement algorithms, assuming frame size is

4.Remember that frames are initially empty. (i)LRU replacement

(ii)FIFO replacement

(iii)Optimal replacement

6. Explain in detail about swapping and thrashing.

7. Write in detail about Virtual memory.


1. What is a file?

2. List the various file attributes.

3. What are the various file operations?

4. What is the information associated with an open file?

5. What are the different accessing methods of a file?

6. What are the operations that can be performed on a directory?

7. What are the most common schemes for defining the logical structure of a directory?

8 What are the various layers of a file system?

9. What are the structures used in file-system implementation?

10. What are the functions of virtual file system (VFS)?

11. Define seek time and latency time.

12. What are the allocation methods of a disk space?

13. What are the advantages of Contiguous allocation?

14. What are the drawbacks of contiguous allocation of disk space?

15. What are the advantages of Linked allocation?

16. What are the disadvantages of linked allocation?

17. What are the advantages of Indexed allocation?

18. Define rotational latency and disk bandwidth.

19. How free-space is managed using bit vector implementation?

Part - B

1. What are files and explain the access methods for files?

2. Write in detail about file concept.

3. Write notes about the protection strategies provided for files.

4. Write in detail about directory structure.

5. Write in detail about File-System Implementation.

6. Write in detail about Allocation methods.


1. Define buffering.

2. Define caching.

3. Define spooling.

4. What are the various disk-scheduling algorithms?

5. What is low-level formatting?

6. What is the use of boot block?

7. What is sector sparing?

8. Define rotational latency and disk bandwidth.

9. What is mean by streams?

10. Define seek time.

11. What is mean by FCFS and SSTF scheduling algorithms?

12. Define SCAN and C-SCAN scheduling algorithms.

13. What is Look Scheduling?

14. Define RAID.

15. Difference between stable storage and tertiary storage.

Part - B

1. Write about the kernel I/O subsystem.

2. Explain the various disk scheduling techniques

3. Write notes about disk management and swap-space management.

4. A hard disk having 2000 cylinders, numbered from 0 to 1999. the drive is currently serving the request at cylinder 143,and the previous request was at cylinder 125.The status of the queue is as follows

86, 1470, 913, 1774,948,1509,1022,1750,130

What is the total distance (in cylinders) that the disk arm moves to satisfy the entire pending request for each of the following disk-scheduling algorithms?

(i)SSTF) (ii) FCFS (iii) SCAN (IV) C-SCAN

5. Explain in various RAID Level.

6.Write notes about Stable storage and tertiary storage.

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