Operating Systems — DU B.Sc. (Prog) Physical Science courses pertaining to Computer Science Previous Year Question Papers

Explain operating system as Resource Manager. Discuss reasons for process termination. Why is dual-mode operation essential for os security? Why is context switching considered overhead? How does multithreading overcome the limitations of Single-threaded execution? Can deadlock occur with only one process? Explain logically. What is the role of the Memory Management u.nit (MMU)? How does swapping improve cpu utilization? Name system call that can be used by a parent process to determine the term ination of child process? Under what circumstances does page fault occur? Differentiate between : (i) mufti-tasking and mufti-user system (iii) time sharing and multiprogramming operating system Explain the structure of a disk with the help of a diagram. 4 Explain the contiguous memory allocation and non-contiguous memory 5 allocation with suitab]e diagram. Why is contiguous allocation faster than non-contiguous allocation? Disk requests come to the disk driver for Cylinders 415, 25,10, 6, 45, 6 15, 37 in that order. A seek operation takes 10 milliseconds to move the disk arin to a cylinder. How much seek time is needed for : (I) First Come First Serve (3) Elevator algorithm. (Moving upward) Note: In all the cases the ar.in is initially at cylinder 25 What is Dead lock? Explain four necessary conditions for dead lock to occur with suhable example. Describe the different methods for prevention and avoidance of dead lock. Consider a system having two processes and three resources. Each process needs a maximum of two resources. Draw resource allocation graph for the same. Is a deadlock possible? b. What do you understand. by demand paging? Explain its.working. Q4 a. Apply first-fit, best-fit, worst-fit for: Memory blocks: 100KB, 500KB, 200KB, 300KB, 600KB Calculate remaining memory after allocation using each. strategy Explain File system in Operating System. State and explainany two file 6 allocation methods. C. Consider a machine with 64 MB physical memory and a 32bit virtual 3 address space. If the page size is 4 KB, what is the approximate size of the page table? Q5 a. Considerthe following: Process Arriv.al Time (ms) Burst Time (ms) Q6 a. b. c. Q7 a. b. c. Find the average waiting time and the turn-around time for the following process scheduling algorithms: (iii) RoundRobin. (Time Quantum = 5 ms) Buffer (TLB) and illustrate it with a s'uitable diagram. Consider the following page reference string how many page faults will 6 occur using LRU and optimal page replacement scheme. Compare the results. 1, 2, 3, 4, 5, 3, 4,1, 6, 7, 8, 7, 8, 9, 7, 8, 9, 5, 4, 5, 4, 2. The number of page frames = 3. Describe the critical section problem with suitable example. What are 5 the requirements of solution the critical-section problem? Explain the performance criteria for process scheduling algorithms. 4 Explain the Layered System Structure of Operating System, with one 4 advantage and one disadvantage.