AL-501 Operating Systems - Nov 2022 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDescribe the evolution of the operating system in detail.
   How to answer

   • Define operating system and need for evolution
   • Serial/batch processing and multiprogramming
   • Time-sharing, personal, parallel, distributed and real-time systems
   • Modern OS features and summary
2. 7 Marks
   bWhat are the major services of an operating system with regard to process management? Explain.
   How to answer

   • Define process management role of OS
   • List services: creation, scheduling, synchronization, communication, deadlock handling
   • Explain each service briefly
   • Importance with example
3. 14 Marks
   Explain different disk allocation methods in detail.
   How to answer

   • Define disk allocation and file allocation problem
   • Explain contiguous allocation with merits/demerits
   • Explain linked and indexed allocation
   • Comparison and examples
4. 14 Marks
   Following is the snapshot of a CPU: Draw the Gantt chart and calculate the turnaround time and waiting time of the jobs for

   1. i)FCFS (First Come First Served)
   2. ii)SJF (Shortest Job First)
   3. iii)SRTF (Shortest Remaining Time First)
   4. iv)RR (Round Robin with time quantum 10) scheduling algorithms

   

   How to answer

   • Tabulate arrival and burst times for P1-P4
   • Draw Gantt charts for FCFS, SJF, SRTF, RR quantum 10
   • Calculate turnaround time = completion - arrival and waiting time
   • Compare average times across algorithms
5. 14 Marks
   Consider the following snapshot of a system: Answer the following questions using the banker's algorithm:

   1. i)What is the content of the matrix Need?
   2. ii)Is the system in a safe state?
   3. iii)If a request from process P1 arrives for (0, 4, 2, 0) can the request be granted immediately?

   

   How to answer

   • Compute Need = Max - Allocation matrix
   • Apply Banker's safety algorithm to find safe sequence
   • Check request (0,4,2,0) of P1 against Need and Available
   • Decide grant and new safe state
6. 7 Marks
   aWhat is Demand paging? Explain.
   How to answer

   • Define demand paging and lazy loading concept
   • Explain page fault handling steps
   • Advantages and performance with effective access time
   • Diagram of demand paging
7. 7 Marks
   bDiscuss about segmentation with an example.
   How to answer

   • Define segmentation and segments
   • Explain segment table with base and limit
   • Illustrate with example and address translation
   • Advantages over paging
8. 7 Marks
   aDifferentiate Synchronous and Asynchronous I/O operations. https://www.rgpvonline.com
   How to answer

   • Define synchronous I/O with blocking behavior
   • Define asynchronous I/O with non-blocking behavior
   • Compare on waiting, concurrency, implementation
   • Examples of each
9. 7 Marks
   bHow I/O request are transferred to hardware devices?
   How to answer

   • Outline I/O request lifecycle from application
   • Explain system call, driver, controller steps
   • Role of interrupts and DMA
   • Path to hardware device
10. 7 Marks
    aConsider the page reference string 1, 0, 2, 5, 3, 0, 1, 0, 2, 4, 0, 3, 0, 4, 2, 4, 3, 4, 1, 4, 0. How many page faults occur for the Optimal and LRU Page replacement algorithms with 4 frames each?
    How to answer

    • State reference string and 4 frames assumption
    • Simulate Optimal replacement counting faults
    • Simulate LRU replacement counting faults
    • Compare fault counts
11. 7 Marks
    bDescribe the actions taken by a thread library to context-switch between user level threads.
    How to answer

    • Define user-level threads and thread library
    • Steps to save current thread context (registers, stack)
    • Steps to restore next thread context without kernel trap
    • Role of scheduler in library
12. 14 Marks
    Write short notes on any two:

    1. a)Mutual Exclusion
    2. b)Disk Mounting
    3. c)Virtual File Systems
    4. d)User level and Kernel level threads
    How to answer

    • Select any two topics from four options
    • Define each with key principles and example
    • Explain advantages/applications
    • Neat diagram where applicable