IGNOU MCA MCS-041 Operating Systems IV FOURTH SEMESTER SOLVED ASSIGNMENTS 2014-2015

IGNOU MCA MCS-041 SOLVED ASSIGNMENTS 2014-2015 Operating Systems IV  FOURTH SEMESTER 

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Course Code : MCS-041
Course Title : Operating Systems
Assignment Number : MCA(4)/041/Assign/2014-15
Maximum Marks : 100
Weightage : 25% Last Dates for Submission : 15th October, 2014 (For July 2014 Session)
                                                                          15th April, 2015 (For January 2015 Session)

This assignment has five questions carrying 80 marks. Answer all questions. Rest 20 marks are for viva voce. You may use illustrations and diagrams to enhance the explanations. Please go through the guidelines regarding assignments given in the Programme Guide.


Question 1: On a disk with 1000 cylinders, numbers 0 to 999, compute the number of tracks the disk arm must move to satisfy all the requests in the disk queue. Assume the last request serviced was at track 345 and head is moving to track 0. The queue in FIFO order contains requests for the following tracks: 123, 874,692, 475, 105, 376. Perform the computation for the following disk scheduling algorithms:
 (a) FIFO (b) SSTF (c) SCAN (d) LOOK

Question 2: Consider the following set of processes, with the length of the CPU burst time given in milliseconds.

Process                             Burst time                            Priority                                                                 P1                                           8                                          3                                                                       P2                                           3                                           1                                                                     P3                                           4                                           4                                                                     P4                                           7                                           2                                                                   P5                                          6                                            5

The processes are assumed to have arrived in the order P1, P2, P3, P4 and P5 all at time 0.


a) Draw four Gantt charts illustrating the execution of these processes using FCFS, SJF a non-preemptive priority (a smaller priority number implies a higher priority) and Round Robin (quantum=2) scheduling.

b) What is the turnaround time of each process for each of the scheduling algorithm in (a)?

c) What is the waiting time of each process for each of the scheduling algorithm in (a)?

d) Which of the schedules in (a) results in minimal average waiting time (overall processes)?

Question 3: 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 following replacement algorithms, assuming three frames? Remember all frames are initially empty. a. FIFO replacement b. LRU replacement c. Optimal Mention the merits and demerits of each of the above algorithms.

Question 4: Android has continued upgrading since it was first launched a few years ago and utilizes a special name each time it releases a new version of the platform. The latest version is Android 4.4.2. Mention its features and also compare this with the earlier versions namely Gingerbread, Ice Cream Sandwich and Jelly Bean.

Question 5: Write a program in C to implement Banker’s Algorithm to avoid Deadlock. Also explain the code briefly.

Question 6: a) What is the cause of thrashing? How does the system detect thrashing? Once it detects thrashing, what can the system do to eliminate this problem?

b) Explain in detail how semaphores and monitors are used to solve the Dining-Philosopher problem.