Questions
Syllabus
Qns. By Syllabus

Semester

Subject

Year

Tribhuwan University

Institute of Science and Technology

2078

Bachelor Level / Second Year / Fourth Semester / Science

B.Sc in Computer Science and Information Technology (CSC264)

(Operating Systems)

Full Marks: 60

Pass Marks: 24

Time: 3 Hours

Candidates are required to give their answers in their own words as for as practicable.

The figures in the margin indicate full marks.

Section A

Long Answers Questions

Attempt any TWO questions.
[2*10=20]
1.
What kind of problem arises with sleep and wakeup mechanism of achieving mutual exclusion? Explain with suitable code snippet.[10]
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 the memory size is 3.[10]
3.
How unsafe state differs from deadlocked state? Consider follows initial state and identify wheather requested 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?

$\begin{array}{|c|c|c|} \hline \text{Process} & \text{Has} & \text{Max} \\ \hline A & 2 & 6 \\ B & 1 & 5 \\ C & 2 & 3 \\ D & 3 & 8 \\ \hline \end{array}$

$Free = 2$
[10]
Section B

Short Answers Questions

Attempt any Eight questions.
[8*5=40]
4.
What is system call? Discuss process of handling system calls briefly. [5]
5.
What is lock variable? Discuss its working and problems associated with it in detail. [5]
6.
Differentiate between internal and external fragmentation? Suppose that we have memory of 100 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? [5]
7.
What is ment by file attributes? Discuss any one technique of implementing directories in detail. [5]
8.
Why the concept of disk interleaving is important? Explain with suitable example. [5]
9.
What is resource allocation graph? Explain the process of detecting deadlocks when there is single instance of each resources with suitable example? [5]
10.
Discuss the concept of SJF and SRTN scheduling algorithms with suitable example. [5]
11.
What approaches are using for managing free disk spaces? Explain linked list approaches with example. [5]
12.
Write short notes on: a. IPC in Linux b. Disk access [5]