CS 2254 OPERATING SYSTEMS QUESTION PAPER

B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2011.

Fourth Semester

Computer Science and Engineering

CS 2254 – OPERATING SYSTEMS

(Common to Information Technology)

(Regulation 2008)

Time : Three hours Maximum : 100 marks

Answer ALL questions.

PART A — (10 × 2 = 20 marks)

1. What does the CPU do when there are no user programs to run?
2. What is the principal advantage of the multiprogramming?
3. Define Mutual Exclusion.
4. What is Semaphore?
5. What is page frame?
6. What is internal fragmentation?
7. A direct or sequential access has a fixed file-size S-byte record. At what
logical location, the first byte of record N will start?
8. Give an example of a situation where variable-size records would be
useful.
9. Writable CD-ROM media are available in both 650 MB and 700 MB
versions. What is the principle disadvantage, other than cost, of the 700
MB version?
10. Which disk scheduling algorithm would be best to optimize the performance of a RAM disk?

PART B — (5 × 16 = 80 marks)

11. (a) (i) Explain the important services of an operating system. (8)
(ii) Discuss in detail the concept of virtual machines, with neat sketch. (8)

Or

(b) Write detailed notes on process control and file manipulation. (16)
12. (a) Explain in detail about any two CPU scheduling algorithms with suitable examples. (16)

Or

(b) (i) What is a deadlock? What are the necessary conditions for a
deadlock to occur? (6)
(ii) How can a system recover from deadlock? (10)
13. (a) Explain about contiguous memory allocation with neat diagram. (16)

Or

(b) What do you mean by paging? Discuss in detail about structure of
page tables with appropriate examples. (16)
14. (a) Write a detailed note on various file access methods with neat sketch.(16)

Or

(b) Discuss the different file allocation methods with suitable example. (16)
15. (a) Describe the important concepts of application I/O interface. (16)

Or

(b) Explain any two disk scheduling algorithms with suitable example. (16)

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2010

Fourth Semester

Computer Science and Engineering

CS2254 — OPERATING SYSTEMS

(Common to Information Technology)

(Regulation 2008)

Time : Three hours Maximum : 100 Marks

Answer ALL Questions

PART A — (10 × 2 = 20 Marks)

1. Mention the objectives and functions of an operating system.
2. Define thread. Differentiate user threads from kernel threads.
3. What is a semaphore? State the two parameters.
4. What is deadlock? What are the schemes used in operating system to handle
deadlocks?
5. Differentiate a page from a segment.
6. What is meant by thrashing? Give an example.
7. Mention the objectives of file management system.
8. Differentiate the various file access methods.
9. What is the need for disk scheduling?
10. What does swap-space management mean?

PART B — (5 × 16 = 80 Marks)

11. (a) (i) Explain the operating system structure and its components. (8) (ii) Explain briefly IPC in Linux. (8) Or (b) (i) Explain Process Control Block. (4) (ii) Describe the differences among short-term, medium-term, and long-term scheduling. (4) (iii) Describe the Inter Process communication in client-server systems. (8) 12. (a) (i) Distinguish between preemptive and non-preemptive scheduling. Explain each type with an example. (8) (ii) What is synchronization? Explain how semaphores can be used to deal with n-process critical section problem. (8) Or (b) (i) Discuss the issues in multiprocessor and real-time scheduling. (8) (ii) Explain Banker’s deadlock-avoidance algorithm with an illustration. (8) 13. (a) (i) Discuss how memory is allocated in variable partition multiprogramming. (6) (ii) Explain memory management in Linux. (10) Or (b) (i) Discuss segmentation in detail. Compare it with paging. (8) (ii) Explain FIFO, LRU and Second-chance page replacement algorithms with an example reference string. (8) 14. (a) (i) Explain linked file allocation method. (6) (ii) Describe Windows XP file system in detail. (10) Or (b) (i) What is the role of Access matrix for protection? Explain. (5) (ii) What is meant by free space management? Explain. (5) (iii) Explain the directory structure of Linux operating system. (6) 15. (a) (i) Explain the services provided by a kernel I/O subsystem. (8) (ii) Explain and compare the C-LOOK and C-SCAN disk scheduling algorithms. (8) Or (b) (i) Write an elaborate note on RAID. (6) (ii) Explain in detail the salient features of Linux I/O. (10)

B.E./B.Tech. degree examination ,november/december 2009 fifth semester (regulation 2004) cs1252-operating systems
part-A(10*2=20 marks)

1.what is the difference between os for mainframe and desktop systems?
2.differentiate long term scheduler from short term scheduler.
3.define critical region.
4.what is meant by monitors?
5.what is a safe state?give the use of state in deadlock avoidance.
6.why paging is used?
7.what is meant by demand paging?
8.define thrashing
9.what is the importance of shells in linux?
10.differentiate worms from virus.

part-B(5*16=80)

11.a) describe in detail the activities involved in sharing of information between two processes.
or
b) write short notes on:
i) virtual machines
ii)hardware protection
12.a) discuss how the dinning philosopher's problem can be solved by monitors.
or
b) explain the various process scheduling algorithms with example.
13.discuss how deadlocks can be avoided and detected.
Or
b)describe segmentation.
14.a)explain the various page replacement algorithms with example
Or
b)why is file protection necessary? explain the techniques used for the file protection.
15.a) discuss the file system in linux
or
b)discuss in detail the disk management techniques folowed in OS