11 06 2024 E TS

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Advanced Operating Systems - Part A, June 11th, 2024 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 — General knowledge - Closed questions (Points 7) Question 2.1 (Points 7) Select the correct answer in the following quiz on general knowledge of operating systems. 0 correct answers will get you a D, up to two 2 correct answers will get you C, up to 4 you’ll get a B, above that you’ll get an A. Solution 1. What is the primary purpose of the ( write_seqlock) function in Linux? • Answer: To allow writers to push through concurrent reads without getting blocked. 2. In the context of the Linux kernel, what is the role of the ’buddy allocator’? • Answer: To allocate continuous ranges of pages using a node-local policy. 3. Which of the following tasks is NOT an accurate description of a ’task’ in Linux? • Answer: It always shares its address space with other tasks. 4. What function is used to create VMAs with an arbitrary backing store explicitly in Linux? • Answer: mmap() 5. In demand paging, which kernel function is used to check VMA’ s permissions of a load/store and could lead to a segmentation fault? • Answer: find_vma() 6. What could happen if a task gets preempted while it is modifying the per-cpu structures without disabling preemption? • Answer: Unexpected behavior due to the current value of ’ smp_processor_id’ may not equal the value when the task was preempted. Exercise 3 — Open questions (Points 15) Question 3.1 (Points 5) Assume the weakest memory model possible and the acquire/release Linux kernel API ( you can’t use locks and/or condition variables ). In the…