PG – 1024

*PG1024* I Semester M.Sc. Examination, January 2015 (Y2K12 Scheme) COMPUTER SCIENCE MCS – 104 : Operating Systems Time : 3 Hours

Max. Marks : 80 PART – A

I. Answer any four of the following :

(8×4=32)

1) What is multi-programming ? How multi-programming in different from multi-processing and distributed processing ?

8

2) Consider the following set of data arriving at time 0.

8

Process

Estimated run-time

Priority

P1

20

2

P2

06

3

P3

11

1

P4

06

4

P5

18

2

Using FCFS, SJF, and RR (quantum = 1) scheduling schemes find a) the turn around time for each process b) the waiting time for each process c) which algorithm results in the minimal average waiting time ? d) give your discussion on the choice of the scheduling algorithm. Give reason. 3) What is deadlock ? What are the possible methods for avoiding deadlocks and discuss their merits ?

8

4) What is semaphore ? Distinguish between binary and counting semaphore.

8

5) What is paging ? Explain the implementation of demand paged memory management.

8

6) The Linux Kernel does not allow paging out of Kernel memory. What are two advantages and two disadvantages of this design decision ?

8

P.T.O.

PG – 1024

*PG1024*

-2-

PART – B II. Answer any four of the following :

(4×12=48)

7) a) What is operating system ? What are the different operating system services ?

6

b) Distinguish between preemptive non-preemptive and co-operative scheduling methods.

6

8) a) What is a process ? Draw a process state transition diagram using five states and explain each transition. b) In Linux, what is the advantage of keeping shared libraries functionality out of the Kernel ? What are its drawbacks ? Explain. 9) a) Explain the difference between deadlock and starvation.

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b) Assume a system with four resources type c = <6, 4, 4, 2 > and the maximum claim table and current allocation tables are shown below. Is this state safe ? Why are why not ? Process

R0

R1

R2

R3

Process

R0

R1

R2

R3

P0

3

2

1

1

P0

2

0

1

1

P1

1

2

0

2

P1

1

1

0

0

P2

3

2

1

0

P2

1

0

1

0

P3

1

1

2

0

P3

1

1

0

0

P4

2

1

0

1

P4

0

1

0

1

Maximum claim table

6

6

Current allocation table

10) a) Explain the process management of LINUX operating system. b) Explain I/O in LINUX.

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11) Discuss in detail about file allocation methods.

12

12) Explain the critical section problem with a example. What are the properties satisfied by a good solution to the critical section problem ? 12 ———————