File System and Operating Systems Time

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Code No: 09A60402

R09
(Common to ECE, ETM)

SET-1
Max. Marks: 75

B. Tech III Year II Semester Examinations, April/May - 2012 OPERATING SYSTEMS Time: 3 hours Answer any five questions All questions carry equal marks --Explain the difference between Multiprogramming and Time sharing. Describe the system view of an operating system also give its services.

1.a) b) 2.a) b)

[15]

What is meant by context switch? Explain various processes involved in a typical context switch. Compare preemptive and non preemptive scheduling methods and explain in detail the SJF and SRTF scheduling policies. [15] What is a semaphore? What are the operations defined on it? Explain critical section and mutual exclusion with respect to producer consumer problem. [15] Give the relative advantages and disadvantages of contiguous memory allocation. Explain the hardware support for implementing page lookup tables. [15] Consider a system with five processes P0 through P4 and three resource types A, B, C. Resource type A has 10 instances, resource type B has 5 instances, and resource C has 7 instances. Suppose that, at time T0, the following snapshot of the system has been taken: Processes Allocation Max Available A B C A B C A B C 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 Answer the following questions using the banker’s algorithm: a) What is the content of the matrix Need? Is the system in a safe state? b) Define what is a safe state and an unsafe state. [15] Discuss the objectives for a file management system. Explain briefly about chained and indexed file allocation techniques with neat diagrams along with merits and demerits. [15] How do system designers choose a particular RAID level? Suppose we have disk with 200 tracks. The disk head starts at track 100 and moving in the direction of decreasing track number. For the following sequence of disk track requests 27, 129, 110, 186, 147, 41, 10, 64, 120. Compute the average seek time for the following disk scheduling algorithms, FIFO, SSTC, SCAN. [15] Explain the major security threats perceived by users and providers of computerbased systems. Discuss the goals of security and protection. [15] ********

3.a) b)

4.a) b) 5.

6.a) b)

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7.a) b)

8.a) b)

www.jntuworld.com

www.jntuworld.com

www.jwjobs.net

Code No: 09A60402

R09
(Common to ECE, ETM)

SET-2
Max. Marks: 75

B. Tech III Year II Semester Examinations, April/May - 2012 OPERATING SYSTEMS Time: 3 hours Answer any five questions All questions carry equal marks --1.a) b) c) 2.a) b) What is an operating system? What are the functions of an operating system? Describe the user view of an operating system. Write a short note on Real-Time systems. [15] Explain what is starvation. When and how starvation occurs? Explain Priority and RR Scheduling algorithms with its merits and demerits. [15] Define critical-section problem. Explain how semaphores are used to solve critical section problem. Differentiate between countable semaphores and binary semaphores. [15] What is demand paging? Explain a typical hardware implementation of address translation in paged segmentation scheme. Explain briefly about LRU and FIFO page replacement algorithms. [15] Consider the following snapshot of a system Processes Allocation Max Available A B CD A B CD ABCD P0 0012 0012 1520 P1 1000 1750 P2 1354 2356 P3 0632 0652 P4 0014 0656 Answer the following questions using the banker’s algorithm: a) What is the content of the matrix Need? Is the system in a safe state? b) If a request from process P1 arrives for (0, 4, 2, 0), can the request be granted immediately? [15] Discuss about the usage information elements of a file directory. What are the advantages and disadvantages of pile file organization over hashed file organization? [15] Describe the physical structure of Magnetic Disks and Magnetic Tapes with its merits and demerits....
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