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V Semester B.E. (CSE/ISE) Degree Examination, Dec. 2014/Jan. 2015 (2K11 Scheme) CI 52 : OPERATING SYSTEMS Time : 3 Hours

Max. Marks : 100

Instruction : Answer any five full questions selecting at least two from each Part. PART – A 1. a) What is the main goal of an OS ? Why it is called as resource manager ?

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b) Explain parallel and multiprogramming systems.

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c) Discuss the various services provided by the OS.

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d) What are system calls ? List any four system calls.

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2. a) What is a process ? Explain the life cycle of a process.

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b) Define critical section problem.

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c) Discuss Diming-philosophers problem in process synchronization.

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d) What are the characteristics of a monitor ?

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3. a) Consider the following set of processes with CPU burst time given in milliseconds. Process P1 P2 P3 P4 P5

Burst time 10 1 2 1 5

Priority 3 1 3 4 2

Draw the Gantt chart and calculate average waiting time and turn around time for the following CPU scheduling algorithms. a) Pre-emptive SJF algorithm b) Pre-emptive and Non-pre-emptive Priority scheduling algorithm.

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b) Define the term co-operating processes. Explain producer-consumer problem.

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c) What is IPC ? Explain blocking send, non-blocking send, blocking receive and non-blocking receive mechanisms.

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4. a) Explain the system model of a Deadlock.

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b) Discuss the necessary conditions required for the Deadlock.

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c) Discuss on Deadlock prevention and avoidance mechanism.

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PART – B 5. a) What are the different memory allocation techniques ? Explain contignous memory allocation, also list its merits and demerits.

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b) What is page fault ? Compare FIFO and LRU page replacement algorithm through an example.

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c) What is thrashing ? How does the system detect thrashing ?

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6. a) Write a note on access methods in directory structure. b) Explain the following disk scheduling algorithms : i) FIFO ii) SCAN iii) C-SCAN.

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7. a) What are the major goals of protection ? Discuss briefly the implementation of access matrix. 10 b) Discuss on threat and threat monitoring in a computer system. 8. Write short notes on :

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i) Real-time O.S. ii) Race condition problem iii) Linux iv) Encryption. —————————