CA5155 OPERATING SYSTEMS anna university previous year question paper





Time: Three hours Maximum: 100 marks

Answer all questions.

PART A – [10 X 2 = 20 marks]

1.What do you mean by graceful degradation in multiprocessor systems?

2.What is system call?

3.What are the various states of a process?

4.Why CPU scheduling is required?

5.List the three requirements that must be satisfied by critical-section problem.

6.Define deadlock.

7.What do you mean by swapping technique?

8.State the principle of locality.

9.What is the use of file control block?

10.What are the free space management techniques?

PART B – [5 X 16 = 80 marks]

11.(a) Discuss about the mainframe system. (8)

(b) Explain the components of an operating system. (8)


12.(a) Explain about the distributed systems. (8)

(b) Discuss the Operating System Services. (8)

13. Consider the following set of processes, with the length of the CPU – burst time given in milliseconds. (16)

Process Burst time Priority
P1 10 3 
P2 1 1 
P3 2 3 
P4 1 4 
P5 6 2 

The process are assumed to have arrived in order P1, P2, P3, P4, P5, all at time 0.
(a)Draw four Gantt charts illustrating the execution of these processes using FCFS, SJF, a non-preemptive 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 algorithm in part (a)?

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


14. (a) Compare long term, short term and medium term process schedulers. (8)

(b) Describe briefly about the Interprocess Communcation. (8)

15. (a) Explain the readers-writers problem using semaphores. (8)

(b) Explain the banker’s algorithm for solving deadlock problem. (8)


16. (a) Explain the scheme for detecting deadlock. (8)

(b) Discuss the various methods for deadlock recovery. (8)

17. (a) Explain the various contagious memory allocation strategies with suitable examples. (8)

(b) Discuss the concept of demand paging. (8) 


18. (a) Consider the page-reference string : 2 3 2 1 5 2 4 5 3 2 5 2. How many page faults occur for the following replacement algorithms, assuming three frames? (12)

(i) FIFO
(ii) LRU
(iii) Optimal

(b) Write a short note on segmentation. (4)

19. (a) Suppose that a disk drive has 5000 cylinders, numbered 0 to 4999. The drive is currently serving a request at cylinder 143 and the previous request was at cylinder 125. The queue of pending request is 86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130. What is the total distance (in cylinders) to satisfy these requests using the following disk-scheduling algorithms? (8)
(i) SCAN
(ii) LOOK

(b) Discuss briefly the schemes for defining the logical structure of a directory. (8)


20. (a) Explain the various methods of allocating disc space. (8)

(b) Describe the components of a Linux system. (8)

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