anna university operating system model question paper

University Question Paper for OS

CS1252 - OPERATING SYSTEMS

(Regulation 2004)

Time: Three hours Maximum: 100 marks

Answer ALL questions.

PART A – (10 x 2=20 marks)

1.Define Real Time Operating System.
2.Define SYSTEM CALLS.
3.What do you mean by a critical section problem?
4.Define the use of monitor.
5.Describe the four necessary conditions for deadlocks.
6.Why should paging be used by operating systems?
7.Define virtual memory.
8.What is the cause of thrashing?
9.What is the Kernel of an operating system?
10.Mention the importance of swap-space management.

PART B - (5 x 16 = 80 marks)

11. (a) (i)How does multi programming help in achieving improved utilization of a computer
system?[Marks 8]
(ii)With necessary diagram explain the term "process" from the operating system point of view.[Marks 8]

Or
(b) (i)Briefly explain the four major functions of an operating system.[Marks 8]
(ii)Give the main feature of the following types of OS outlining their limitations and strengths : Interactive Time sharing OS, Real Time OS. [marks 8]

12. (a) Consider the following set of processes, with the length of CPU-burst time given in millisecond. [marks 16]
Process Burst time Priority
p1 10 3
p2 1 1
p3 2 3
p4 1 4
p5 5 2
The processes are assumed to have arrived in order p1,p2,p3,p4,p5 all at time 0. (i) Draw Gantt chats 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 (ii) What is the turn around time of each process for each of the scheduling algorithms in part (i)?

Or
(b) (i)What two advantages do threads have over multiple processes?
What major disadvantage do they have? Suggest one application that would benefit from the use of threads, and one that would not. [marks 6]
(ii) Define the requirement of the correct solution.How semaphores are used to solve dining philosophers problem. [marks 10]

13. (a) An operating system contains three resource classes, namely R1, R2 and R3. The number of resource units in these classes is 7,7 and 10 respectively.The current resource allocation state is as shown below :[marks 16]
Process Allocated Resources Maximum Requirement

R1 R2 R3 R1 R2 R3

P1 2 2 3 3 6 8

P2 2 0 3 4 3 3

P3 1 2 4 3 4 4

(i) Is the current allocation state safe?[Marks 4]
(ii)Would the following requests be granted in the current state?
(1) Process P1 requests(1, 1, 0) [Marks 4]
(2) Process P3 requests(0, 1, 0) [Marks 4]
(3) Process P2 requests(0, 1, 0) [Marks 4]

Or
(b) (i)Explain some of the most common techniques for structuring the page table. [marks 8]
(ii)Explain the princples of segmentation with examples. [marks 8]

14. (a) Consider the following page reference string : [marks 16]
1,2,7,8,3,4,2,1,4,2,5,6. How many page faults would occur for the following page replacement algorithms, assuming an allocation of 3 frames?

(i) LRU [marks 5]
(ii) FIFO [marks 5]
(iii) Optimal. [marks 6]

Or
(b) (i) Explain the concept of demand paging. [marks 8]
(ii) How does the system detect trashing? Once it detect trashing what the system do to eliminate this problem? [marks 8]

15. (a) (i) Describe the salient features of the file system of UNIX. [marks 8]
(ii)Explain UNIX buffer cache mechanism. [marks 8]

Or
(b) (i) Explain different disk scheduling Techniques. [marks 8]
(ii) Explain different directory implementation methods. [marks 8]

CA5155 OPERATING SYSTEMS

(REGULATION 2007)

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)

Or

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)?

Or

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)

Or

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)

Or

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)

Or

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

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

CS 333 – OPERATING SYSTEMS

Time: Three hours Maximum:100 marks

Answer ALL questions
PART A – (10* 2= 20 marks)

1. What is Time Sharing System?
2. What is the main advantage of the layered approach to system design.
3. What is job scheduler? What is CPU scheduler?
4. What are the various process states?Depict process state diagram.
5. Explain any four scheduling criteria involved in CPU scheduling.
6. Consider a logical address space of eight pages of 1024 words each, mapped
onto a physical memory of 32 Frames. How many bits are there in logical
address?
7. What is sequential address method? Mention its merits and demerits.
8. Define single level directory structure. Give one example.
9. What is a bit vector?
10. Mention any two features of linux file system.

PART B - ( 5 * 16 = 80 marks )

11. (i) Describe Working-Set model. (10)
(ii) Describe paging with illustrative example. (6)

12. (a) (i) Consider the following set of processes , with the length of the CPU
burst time given in milliseconds.
Process Burst time Priority

P1 8 3
P2 3 1
P3 4 4
P4 2 2
P5 6 5

The processes are assumed to have arrived in the order P1, P2, P3,
P4 and P5 all at time 'O'.

(1) Draw four Gantt charts illustrating the execution of these
processes using FCFS, SJF,A nonpreemptive priority (a
smaller priority number implies a higher priority) and RR
(quantum = 2) scheduling.

(2) What is the turn around time of each process for each of the
scheduling algorithms in part (1).

(3) What is the waiting time of each process for each of the
scheduling algorithms in part (1).

(4) Which of the schedules in part (1) results in the minimal
average waiting time(over all processes) (12)

(ii) Explain the three requirements that a solution to critical-section
problem must satisfy. (4)

Or

(b) (i) Describe an algorithm which satisfies all the conditions of critical section problem and also prove how it satisfies all the conditions. (6)

(ii) Describe deadlock prevention methods

(1) Hold and wait

(2) Circular wait

(3) No preemption. (10)

13. (a) (i) Describe internal and external fragmentation with illustrative examples. (8)

(ii) Describe segmentation with its hardware. (8)

Or

(b) (i) Describe multilevel paging with example. (8)

(ii) Describe hardware support of paging with TLB. (8)

14. (a) Describe place replacement algorithms

(i) FIFO algorithm

(ii) Optimal algorithm

(iii) LRU algorithm with illustrative example. (16)

Or

(b) (i) Describe the layered design of file-system organisation. (10)

(ii) Describe the file system mounting. (6)

15. (a) Describe the following methods for allocating disk space.

(i) Linked allocation.

(ii) Contiguous allocation. (16)

Or

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

(ii) Describe process scheduling in Linux system. (8)