Computer Science Engg. (Semester 5)
TOTAL MARKS: 100
TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.
1 (a) What is an Opeating System? Bring out the requirements of.
(i) Real time operating systems
(ii) Distributed operating systems. (10 marks)
1 (b) What are system calls? Explain the different categories of the system calls.(10 marks)
2 (a) Explain the process state with a diagram. What is the need for a context switch?(7 marks)
2 (b) What are the differences between user level threads and kernal supported threads?(5 marks)
2 (c) For the following example calculate average waiting time and average turn around time by using FCFS, preemptive SJF and RR (1 time unit) CPU scheduling algorithms.
| Jobs | Arrival time | Brust time |
| P1 | 0 | 8 |
| P2 | 1 | 4 |
| P3 | 2 | 9 |
| P4 | 3 | 5 |
(8 marks)
3 (a) What is critical section problem? How does a semaphore solve the critical section problem? Discuss whether semaphore satisfy the three requirements for a solution to the critical section problem.(8 marks)
3 (b) What are monitors? Explain with an example program request.(4 marks)
3 (c) Describe the monitor solution to the classical dining philospher's problem.(8 marks)
4 (a) What is deadlock? Explain the necessary conditions for its occurrence.(6 marks)
4 (b) Explain with an example how resource allocation graph is used to describe the deadlock.(6 marks)
4 (c) System consists of five processes (P0, P1, P2, P3, P4) and three source (R1, R2, R3). Resouce type R1 has 10 instances, resources type R2 has 5 instances and R3 has 7 instances. THe following snapshot of the system has been take:
| Jobs | Allocation | Max | Available |
| R1 | R2 | R3 | R1 | R2 | R3 | R1 | R2 | R3 |
| P0 | 0 | 1 | 0 | 7 | 5 | 3 | 3 | 3 | 2 |
| P1 | 2 | 0 | 0 | 3 | 2 | 2 | | | |
| P2 | 3 | 0 | 2 | 9 | 0 | 2 | | | |
| P3 | 2 | 1 | 1 | 2 | 2 | 2 | | | |
| P4 | 0 | 0 | 2 | 4 | 3 | 3 | | | |
Calculate the content of matrix need and find out safe sequence by using Banker's algorithm.(8 marks)
5 (a) Distinguish between:
(i) Logical address space and physical address space
(ii) Internal fragmentation and external freagmentation
(iii) Paging and segmentation(6 marks)
5 (b) Explain with the help of supporting hardware diagram how the TLB improves the performance of a demand paging system.(10 marks)
5 (c) Given memory partitions of 100 k, 500 k, 200 k, 300 k and 600 k (in order) how would each of the first fit, best fit and worst fit algorithms work place processes of 212 k, 417 km, 112 k and 426 k (in order)? Which algorithm makes the most effiecient use of memory?(4 marks)
6 (a) Explain the different types of files.(5 marks)
6 (b) Name the different file allocation methods. Explain the linked allocation of file implementation with merits and demetis.(8 marks)
6 (c) Define file system. Explain the different directory structure.(7 marks)
7 (a) What is disk scheduling? Explain any three disk scheduling methods with examples.(10 marks)
7 (b) What is swap space management? Explain.(5 marks)
7 (c) What is access matrix? Explain the access matrix with domains as objects.(5 marks)
Write short notes on the following :-
8 (a) Process management in Linux.(6 marks)
8 (b) Page replacement algorithms.(8 marks)
8 (c) Steps in handling a page fault.(6 marks)
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