CY-404 Operating Systems - Jun 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
   aWith a neat diagram, explain the layered structures of UNIX operating system.
   How to answer

   • Definition of layered approach in UNIX
   • Layers: hardware, kernel, system calls, libraries/shell, applications
   • Function of each layer
   • Neat labelled diagram of layers
2. 7 Marks
   bWhat are the advantages and disadvantages of using the same system call interface for manipulating both file and device?
   How to answer

   • Meaning of unified system call interface for files and devices
   • Advantages: uniformity, simplicity, extensibility
   • Disadvantages: overhead, loss of device-specific control
   • Example of file vs device operations
3. 7 Marks
   aWhat are the advantages of inter process communication? How communication takes place in a shared memory environments Explain.
   How to answer

   • Definition of inter process communication (IPC)
   • Advantages: cooperation, speedup, modularity, information sharing
   • Shared memory model vs message passing
   • How communication occurs in shared memory with example
4. 7 Marks
   b

   Assume the following work load in a system

   Process	Arrival Time	Burst Time
   P1	5	5
   P2	4	6
   P3	3	7
   P4	1	9
   P5	2	2
   P6	6	3

   Draw a Gantt chart illustrating the execution of these jobs using Round-Robin algorithm and also calculate average waiting time and average turnaround time.

   How to answer

   • List arrival and burst times for P1-P6
   • Apply Round-Robin scheduling to build Gantt chart
   • Compute completion, turnaround and waiting times
   • Calculate average waiting time and average turnaround time
5. 7 Marks
   aWhat is a Process? Explain about various fields of Process Control Block.
   How to answer

   • Definition of process and program vs process
   • Purpose of Process Control Block (PCB)
   • Various fields: PID, state, PC, registers, scheduling info, memory, I/O
   • Diagram of PCB structure
6. 7 Marks
   bWhat is dining philosophers problem? Discuss the solution to dining philosophers problem using monitors.
   How to answer

   • Statement of dining philosophers problem with 5 philosophers
   • Need for synchronization to avoid deadlock/starvation
   • Monitor-based solution with states and procedures
   • Explanation of pickup/putdown using condition variables
7. 7 Marks
   aExplain the concepts of demand paging in detail with neat diagram.
   How to answer

   • Definition of demand paging and lazy loading
   • Page fault handling steps
   • Role of valid-invalid bit and page table
   • Neat diagram of demand paging mechanism
8. 7 Marks
   bGiven memory partition of 100 kb, 500 kb, 200 kb and 600 kb (in order). Show with neat sketch how would each of the first fit, best fit and worst fit algorithms place processes of 412 kb, 317 kb and 326 kb (in order)
   How to answer

   • Rules of first fit, best fit and worst fit
   • Step-by-step placement of 412 kb, 317 kb, 326 kb in 100, 500, 200, 600 kb partitions
   • Neat sketch for each algorithm
   • Comparison of memory utilization and fragmentation
9. 7 Marks
   aWhat is a Virtual Memory? Discuss the benefits of virtual memory techniques.
   How to answer

   • Definition of virtual memory
   • How virtual memory extends physical memory
   • Benefits: larger address space, multiprogramming, sharing
   • Protection and efficient memory use
10. 7 Marks
    bExplain Resource Allocation Graph algorithm for deadlock avoidance.
    How to answer

    • Concept of deadlock and resource allocation graph
    • Components: processes, resources, request and assignment edges
    • Use of claim edge for avoidance
    • Cycle detection and safe allocation decision
11. 7 Marks
    aWrite in detail about file attributes, operations, and types and structures.
    How to answer

    • Definition of file and file attributes
    • Common operations: create, read, write, delete, seek
    • File types and access methods
    • File structures: sequential, indexed, etc.
12. 7 Marks
    bExplain in detail about various ways of accessing disk storage.
    How to answer

    • Overview of disk storage organization
    • Ways of accessing: sequential, direct, indexed
    • Role of file allocation methods
    • Advantages of each access method
13. 7 Marks
    aExplain and compare the FCFS and SSJF disk scheduling algorithm.
    How to answer

    • Working of FCFS disk scheduling
    • Working of SSJF disk scheduling
    • Comparison on seek time, fairness, starvation
    • Example illustrating head movement
14. 7 Marks
    bExplain the Indexed allocation of disk space with examples.
    How to answer

    • Concept of indexed allocation with index block
    • Structure of index and data blocks
    • Example of file access using index
    • Advantages and disadvantages
15. 14 Marks
    Discuss the following

    1. i)I/O buffering
    2. ii)Kernel I/O subsystem
    3. iii)Concurrent I/O
    4. iv)Interrupt Driven
    How to answer

    • Definition and purpose of I/O buffering
    • Functions of kernel I/O subsystem
    • Meaning of concurrent I/O
    • Working of interrupt-driven I/O