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Advanced Operating Systems - Part A, February 1st 2022 Exercises and solutions Exam finalization Question 1.1 This is part A of the AOS’s exam and today you are finalising your entire grade. You must express now how you have finalised part B. The answer is mandatory for the entire exam. Exercise 2 — Open and closed questions (Points 15) Question 2.1 (Points 5) Describe the Linux’s CFS scheduling policy by highlighting the goals, the most important parameters affecting it and its difference with previous versions such as the O(1) scheduler. Question 2.2 (Points 5) Describe goals and the operating principles of the page cache in Linux, by highlighting the main structures in- volved. Question 2.3 (Points 3) What is UEFI? How the boot process works on machines equipped with it? Question 2.4 (Points 2) What is KVM? Can you roughly describe its operating principles. Exercise 3 — Scheduling (Points 7) Question 3.1 (Points 7) Given the following Gantt chart: and assuming that all tasks have finished their execution, identify • The scheduling algorithm being used (briefly justify the answer) • The task parameters (filling up the appropriate table below) • Calculate the total overhead of all the context switches due to preemptions considering a context switch overhead of t=0.1 units of time • Briefly describe how it is possible to reduce this total overhead and why this may be disadvantageous Solution • The scheduler is preemptive at constant time intervals. Therefore, the scheduling algorithm is Round-Robin (RR) with a quantum of q = 3 units of time. • The task parameters are: Task Arrival time ( Ai) Completion time ( Ci) Turnaround time ( Zi) T1 0 12 24 T2 1 2 4 T3 2 1 4 T4 10 9 20 T5 20 5 12 • The number of preemptions is 3(T 1) + 0(T 2) + 0(T 3) + 2(T 4) + 1(T 5) = 6 The…