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Code No: RT31055 R13 SET – 1

III B. Tech I Semester Regular Examinations, November – 2015 OPERATING SYSTEMS (Common to CSE and IT)

Time: 3 hours Max. Marks: 70

Note: 1. Question Paper consists of two parts (Part-A and Part-B)
2. Answering the question in Part-A is compulsory
3. Answer any THREE Questions from Part-B

PART –A

1 a) Define Operating System. List the objectives of an operating system. [3M]
b) With a neat diagram, explain various states of a process. [4M]
c) Give the Peterson’s solution to the Critical section problem. [4M]
d) Distinguish between Logical and Physical address space. [3M]
e) What are the necessary conditions for the occurrence of deadlock? [4M]
f) What are the various attributes that are associated with an opened file? [4M]

PART –B

2 a) With a neat diagram, explain the layered structure of UNIX operating system. [8M]
b) What are the advantages and disadvantages of using the same system call
interface for manipulating both files and devices?
[8M]

3 a) What is a process? Explain about various fields of Process Control Block. [8M]
b) What are the advantages of inter-process communication? How communication
takes place in a shared-memory environment? Explain.
[8M]

4 a) What is a Critical Section problem? Give the conditions that a solution to the
critical section problem must satisfy.
[8M]
b) What is Dining Philosophers problem? Discuss the solution to Dining
philosopher’s problem using monitors.
[8M]

5 a) What is a Virtual Memory? Discuss the benefits of virtual memory technique. [8M]
b) What is Thrashing? What is the cause of Thrashing? How does the system
detect Thrashing? What can the system do to eliminate this problem?
[8M]

6 a) What is a deadlock? How deadlocks are detected? [8M]
b) Explain the Resource-Allocation-Graph algorithm for deadlock avoidance. [8M]

7 a) Briefly explain about single-level, two-level and Tree-Structured directories. [8M]
b) Explain and compare the SCAN and C-SCAN disk scheduling algorithms. [8M]

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Code No: RT31055 R13 SET – 2

III B. Tech I Semester Regular Examinations, November- 2015
OPERATING SYSTEMS
(Common to CSE and IT)

Time: 3 hours Max. Marks: 70

Note: 1. Question Paper consists of two parts (Part-A and Part-B)
2. Answering the question in Part-A is compulsory
3. Answer any THREE Questions from Part-B

PART –A

1 a) Explain how multiprogramming increases the utilization of CPU. [3M]
b) What are the advantages of inter-process communication? Also explain various
implementations of inter-process communication.
[4M]
c) What is a Semaphore? Also give the operations for accessing semaphores. [4M]
d) What is the purpose of Paging and Page tables? [3M]
e) What are the various methods for handling deadlocks? [4M]
f) Briefly explain the indexed allocation method. [4M]

PART -B

2 a) Explain the Dual-Mode operation of an operating system. [8M]
b) Mention the objectives and functions of Real-Time Embedded systems. [8M]

3 a) With a neat sketch, explain the process state diagram. [8M]
b) What are the criteria for evaluating the CPU scheduling algorithms? Why do
we need it?
[8M]

4 a) What is a semaphore? List the types of semaphores and Show that, if the wait()
and signal() semaphore operations are not executed atomically, then mutual
exclusion may be violated.
[10M]
b) Discuss the Bounded-Buffer problem. [6M]

5 a) What is a page fault? Explain the steps involved in handling a page fault with a
neat sketch.
[8M]
b) Consider the following page reference string:
1,2,3,4,2,1,5,6,2,1,2,3,7,6,3,2,1,2,3,6
How many page faults would occur for the optimal page replacement
algorithm, assuming three frames and all frames are initially empty.
[8M]

6 a) Write about deadlock conditions and bankers algorithm in detail. [10M]
b) Discuss various techniques to recover from the deadlock. [6M]

7 a) Write in detail about file attributes, operations and types and structures. [8M]
b) Explain in detail about various ways of accessing disk storage. [8M]
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Code No: RT31055 R13 SET – 3

III B. Tech I Semester Regular Examinations, November- 2015
OPERATING SYSTEMS
(Common to CSE and IT)

Time: 3 hours Max. Marks: 70

Note: 1. Question Paper consists of two parts (Part-A and Part-B)
2. Answering the question in Part-A is compulsory
3. Answer any THREE Questions from Part-B

PART –A

1 a) What are the various security issues that arise in multiprogramming and time
shared systems?
[3M]
b) Describe the differences among short-term, medium-term, and long-term
scheduling.
[4M]
c) Briefly explain the Readers-Writers problem. [4M]
d) What are the disadvantages of single contiguous memory allocation? [3M]
e) Explain the various ways of aborting a process in order to eliminate
deadlocks.
[4M]
f) What is the drawback of Network-attached storage systems? [4M]

PART -B

2 a) With a neat sketch, describe the services that an operating system provides to
users, processes and other systems.
[8M]
b) Distinguish between client-server and peer-to-peer models of distributed
systems.
[8M]
3 a) Define a Thread? Give the benefits of multithreading. What resources are used
when a thread is created? How do they differ from those used when a process
is created?
[8M]
b) Explain the Round Robin scheduling algorithm with a suitable example. [8M]
4 a) State the Critical Section problem. Illustrate the software based solution to the
Critical Section problem.
[8M]
b) How does the signal() operation associated with monitors differ from the
corresponding operation defined for semaphores.
[8M]
5 a) What are the disadvantages of single contiguous memory allocation? Explain. [6M]
b) Discuss the hardware support required to support demand paging. 10M
6 a) How does deadlock avoidance differ from deadlock prevention? Write about
deadlock avoidance algorithm in detail.
10M
b) Is it possible to have a deadlock involving only a single process? Explain. [6M]
7 a) Explain the various methods for free-space management. 10M
b) Discuss various issues involved in selecting appropriate disk scheduling
algorithm.
[6M]
-000-

Code No: RT31055 R13 SET – 4

III B. Tech I Semester Regular Examinations, November- 2015
OPERATING SYSTEMS
(Common to CSE and IT)

Time: 3 hours Max. Marks: 70

Note: 1. Question Paper consists of two parts (Part-A and Part-B)
2. Answering the question in Part-A is compulsory
3. Answer any THREE Questions from Part-B

PART –A

1 a) Explain the importance of Real-Time Embedded systems. [3M]
b) Define Thread. Write the differences between user-level and kernel-level
threads.
[4M]
c) Define Monitor. Explain how it overcomes the drawback of semaphores. [4M]
d) Explain how demand paging affects the performance of a computer system. [4M]
e) Write about Resource-Allocation graph. [4M]
f) Explain the bit vector representation of free space management. [3M]

PART -B

2 a) What is a System call? Explain the various types of system calls provided by
an operating system.
[8M]
b) What is the purpose of interrupts? What are the differences between a trap and
an interrupt? Can traps be generated by a user program? Explain the purpose
with an example.
[8M]
3 a) Distinguish between preemptive and non-preemptive scheduling. Explain each
type with an example.
[8M]
b) Describe the actions taken by a thread library to context-switch between userlevel threads.
[8M]
4 a) What is synchronization? Explain how semaphores can be used to deal with nprocess critical section problem.
[8M]
b) Discuss Mutual-exclusion implementation with test and set() instruction. [8M]
5 a) Explain the difference between External fragmentation and Internal
fragmentation. How to solve the fragmentation problem using paging.
[8M]
b) Discuss various issued related to the allocation of frames to processes. [8M]
6 a) Discuss the necessary conditions that cause deadlock situation to occur. [8M]
b) Discuss various methods for the prevention of deadlocks. [8M]
7 a) Explain the Indexed allocation of disk space. [8M]
b) Explain and compare the FCFS and SSTF disk scheduling algorithms. [8M]
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