Operating Systems 2078

Section A

Long Answer Questions.

Attempt any Two questions            (2 x 10 = 20)

1. What kind of problem arises with sleep and wakeup mechanism of achieving mutual exclusion? Explain with suitable code snippet.

2. why OPR is best but not practically feasible page replacement algorithm? Calculate the number of page faults for OPR, LRU and Clock page replacement algorithm for the reference string: 1, 3, 4, 2, 3, 5, 4, 3, 1, 2, 4, 6, 3, 2, 1, 4, 2. Assume that memory size is 3.

3. How unsafe state differs from deadlock state? Consider following initial state and identify wheather requested resource is and granted or denies for the given cases.

- What will happen if process D request 1 resource?

- what will happen if process A request 1 resource?

Section B

Short Answer Questions.

Attempt any Eight questions.            (8 x 5 = 40)

4. What is system call? Discuss process of handling system calls briefly.

5. What is lock variable? Discuss its working and problems associated with it in detail.

6. Differentiate between internal and external fragmentation? Suppose that we have memory of 1000 KB with 5 partitions of size 150 KB, 200 KB, 250 KB, 100 KB, and 300 KB. Where the processes A and B of size 175 KB and 125 KB will be loaded, if we used Best-Fit and Worst-Fit strategy?

7. What is meant by file attributes? Discuss any one technique of implementing directories in detail.

8. Why the concept of disk interleaving is important? Explain with suitable example.

9. What is resource allocation graph? Explain the process of detecting deadlocks when there is single instance of each resource with suitable example?

10. Discuss the concept of SJF and SRTN scheduling algorithms with suitable example.

11. What approaches are used for managing free disk spaces? Explain linked list approach with suitable example.

12. Write short notes on:

        - IPC in Linux

        - Disk access