OPERATING SYSTEMS II B.Tech II Semester (R07) Regular/supply Examinations, Apr- 2010

Code No: T1221
II B.Tech II Semester (R07) Regular/supply Examinations, Apr- 2010
OPERATING SYSTEMS
(Information Technology)
Time: 3 Hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. a) What is an operating system? Explain the structure of an Operating system.
b) Explain various types of system calls.
2. a) Explain deterministic modeling for scheduling algorithm evaluation.
b) Explain the Non-preemptive and preemptive SJF scheduling algorithm with an
example.
3. a) Explain the locking protocol for concurrency control.
b) Explain the synchronization in Linux operating system.
4. a) Explain memory swapping mechanism.
b) Explain the difference between internal fragmentation and external fragmentation.
c) What is Thrashing? Explain the causes of thrashing.
5. a) Explain the necessary conditions for deadlock.
b) Explain the deadlock avoidance.
6. a) Explain the file access methods.
b) Explain acyclic graph directories.
7. a) Explain swap-space management with an example.
b) Describe stable storage implementation.
8. a) Explain program Threats.
b) Explain the Windows XP security model.

Code No: T1221
II B.Tech II Semester (R07) Regular/supply Examinations, Apr- 2010
OPERATING SYSTEMS
(Information Technology)
Time: 3 Hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. a) Explain how an Operating system acts as a resource manager.
b) Explain various types of system calls.
2. a) Explain the criteria for CPU scheduling.
b) Explain priority scheduling and round robin scheduling algorithms with an
example.
3. a) What are the special instructions used for mutual exclusion ? Explain them.
b) Explain the synchronization in windows operating system.
4. a) Explain contiguous memory allocation mechanism.
b) Explain the techniques for structuring the page table.
5. a) Explain deadlock prevention.
b) Explain the transformation of I/O requests to hardware operations.
6. a) What is a file? Explain the attributes of a file.
b) Explain disk allocation methods.
7. a) Explain the following disk management aspects.
i) Disk initialization ii) Booting from Disk
iii) Bad-Block recovery
b) Explain the problems with RAID structure.
8. a) What are the goals of protection.
b) Discuss the strengths and weaknesses of implementing an access
matrix using access lists that are associated with objects.
c) Briefly, explain intrusion detection system..

Code No: T1221
II B.Tech II Semester (R07) Regular/supply Examinations, Apr- 2010
OPERATING SYSTEMS
(Information Technology)
Time: 3 Hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. a) Describe Real time systems.
b) Explain Operating system services.
2. a) Explain FCFS and Round robin scheduling algorithms with an example.
b) Explain the scheduling in Linux operating system.
3. a) Explain the critical section problem.
b) What is a semaphore? Explain the usage and implementation of semaphores.
4. a) Discuss the hardware support required to support demand paging.
b) Explain the optimal and LRU page replacement algorithms with an example.
5. a) Explain the necessary conditions for Deadlock.
b) Explain the kernel services related to I/O subsystem.
6. a) Explain the free-space management techniques.
b) Describe virtual file systems.
7. a) Define the following disk parameters.
i) Seek time ii) Rotational Delay iii) Transfer Time
b) Explain any three disk scheduling algorithms.
8. a) Explain system and network threats.
b) Explain user authentication techniques.

II B.Tech II Semester (R07) Regular/supply Examinations, Apr- 2010
OPERATING SYSTEMS
(Information Technology)
Time: 3 Hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. a) Explain the functions of an operating system.
b) Describe distributed systems.
2. a) Explain the criteria for CPU scheduling algorithms.
b) Consider the following set of processes with the length of the CPU
burst given in milliseconds.
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 the order P1, P2, ….P5 all at time 0.
i) Draw four Gantt charts that illustrates the execution of these processes using
the following scheduling algorithms: FCFS, SJF, Non-Preemptive priority
(A smaller priority number implies a higher priority ) and Round Robin
( Quantum=1).
ii) What is the turnaround time of each process for each of the heduling
algorithms in part(i) ?
iii) What is the waiting time of each process for each of the Scheduling
algorithms in part(i) ?
iv) Which of the algorithms in part(i) results in the minimum average waiting
time (over all processes).
3. a) Explain the Peterson’s solution to the critical section problem.
b) Explain the solution to the Dining-Philosopher problem using monitors.
4. a) Explain the simple paging mechanism.
b) Explain FIFO and LRU page replacement algorithms with an example.
5. a) Explain the life cycle of an I/O request.
b) Explain about STREAMS.
6. a) Explain the structure of a file system.
b) Explain tree – structured directories.
7. a) Explain the physical structure of Magnetic disks.
b) Explain SSTF and SCAN disk scheduling algorithms.
8. a) Describe several methods of implementing the Access matrix.
b) Explain program threats.