# MCS 041

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```							MCS – 041 Question 1: Write a monitor solution to the Readers/Writers problem. Question 2: Consider the following jobs: Job # A B C D Arrival time 0 2 3 5 Run time 5 4 5 3

a) Using the SJF method, compute the completion times of the above jobs, average turn around time and average waiting time. b) Using the SRTF (Shortest Remaining Time first) method, compute the the completion times of the above jobs, the average turn around time and the average waiting time. Note that SRTF is SJF with preemption. Completion time - arrival time = turnaround time c) Using the Round Robin method (with Quantum = 2), compute the completion times of the above jobs and the average waiting time. Question 3: What will be the number of page faults for the algorithms (FIFO, LRU and Optimal) for the following page reference string: 1,2,3,3,5,1,2,2,6,2,1,5,7,6,3 for a memory with 4 frames? Question 4: There is a total of 15 units of R1 (resource 1) and 7 units of R2 and the system is in the following state (again call it S0): Process P0 P1 P2 P3 Max R1 R2 42 57 46 64 Allocation R1 R2 22 41 31 32

a) Show that the above state is a safe state. You must come up with a complete sequence of jobs.

b) If the system is in state S0, should a request of (2,0) units by P2 be granted? You must give a sequence. c) If the system is in state S0, should a request of (0,2) units by P2 be granted? You must give a sequence. d) If the system is in state S0, should a request of (2,0) units by P3 be granted? You must give a sequence. e) If the system is in state S0, should a request of (1,1) units by P2 be granted? You must give a sequence. Question 5: a. List the security attacks that cannot be prevented by encryption. b. Describe why authentication is important for file protection. Question 6: a. Discuss in detail the Process management, Memory management, I/O and File management and Security and Protection in LINUX Operating System.

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