Tribhuvan University
Bachelor of Science in Computer Science and Information Technology
Semester 4 · TU Board 2079
Course Title: Operating Systems (CSC264)
Full Marks: 60Pass Marks: 24Time: 3 hours
Candidates are required to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.
Group A
(2 × 10 = 20)
- 1.10
Discuss about single level and two level directory system. Consider the following process and answer the following questions.
Process
Allocation
Max
Available
A B C D
A B C D
A B C D
P0
0 0 1 2
0 0 1 2
1 5 2 0
P1
1 0 0 0
1 7 5 0
P2
1 3 5 4
2 3 5 6
P3
0 6 3 2
0 6 5 2
P4
0 0 1 4
0 6 5 6a) What is the content of matrix Need?
b) Is the system in safe state?
c) If P1 request (0,4,2,0) can the request be granted immediately.
- 2.10
When does race condition occur in inter process communication? What does busy waiting mean and how it can be handled using sleep and wakeup strategy?
- 3.10
Define shell and system call. suppose a disk has 201 cylinders, numbered from 0 to 200. At same time the disk arm is at cylinder 95, and there is a queue of disk access requests for cylinders 82,170,43,140,24,16 and 190. Calculate the seek time for the disk scheduling algorithm FCFS,SSTF,SCAN and C-SCAN.
Group B
(8 × 5 = 40)
- 4.5
Distinguish between starvation and deadlock . How does the system schedule process using multiple queues?
- 5.5
List any two demerits of disabling interrupt to achieve mutual exclusion. Describe about fixed and variable partitioning
- 6.5
For the following dataset, compute average waiting time for SRTN and SJF.
Process
Arrival Time
Burst Time
P0
0
7
P1
2
4
P2
4
1
P3
5
4 - 7.5
Discuss the advantages disadvantages of implementing file system using Linked List.
- 8.5
Consider the page references 7,0,1,2,0,3,0,4,2,3,0,3,2, Find the number of page fault using OPR and FIFO, with 4 page frame.
- 9.5
Describe the working mechanism of DMA.
- 10.5
What is the task of disk controller ? List some drawback of segmentation.
- 11.5
Write the structure and advantages of TLB.
- 12.5
Why do we need the concept of locality of reference ? List the advantages and disadvantages of Round Robin algorithm.
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