• Attempt any five questions.
• All questions carry equal marks.
What is Operating System? Discuss different types of Operating System.
What do you understand by system call? List and explain four system calls used for process management.
What are different functions provided by Operating System. Also discuss various services provided by an operating system by explaining different methods of providing these services through commands and system calls with suitable examples.
Define a file and explain the file concept in operating systems. Discuss the user's view and system programmer's view of a file system with suitable examples.
Discuss disk space allocation methods used in file systems. Explain contiguous, linked and indexed allocation with neat diagrams, advantages, and disadvantages.
Explain directory structures used in file systems. Also discuss file protection mechanisms and access control methods.
What are threads? Explain the concept of multithreading. Compare user level threads and kernel-level threads in terms of creation, scheduling, performance and overhead.
Discuss the protection and security issues in operating systems. Explain various protection and security mechanisms such as authentication, access control, encryption and auditing.
Define deadlock. Explain deadlock characterization and discuss the four necessary conditions for deadlock to occur in a system.
Explain producer consumer problem and its solution using semaphore. Explain how synchronization and mutual exclusion are achieved.
Consider the following set of processes with their arrival time (AT) and burst time (BT). Draw the Gantt chart and calculate the average waiting time and average turnaround time for each process using the First Come First Serve (FCFS) and Shortest Remaining Time First (SRTF) scheduling algorithm.
| Process | Arrival Time (ms) | Burst Time (ms) |
|---|---|---|
| P1 | 0 | 8 |
| P2 | 1 | 4 |
| P3 | 2 | 9 |
| P4 | 3 | 5 |
Explain non-contiguous memory allocation techniques. Describe paging, segmentation and paged segmentation with neat diagrams.
Consider the following snapshot of a system and answer the following questions using the Banker's Algorithm:
\hline \text{Process} & \multicolumn{3}{|c|}{\text{Allocated}} & \multicolumn{3}{|c|}{\text{Maximum}} & \multicolumn{3}{|c|}{\text{Available}} \\ \hline & R1 & R2 & R3 & R1 & R2 & R3 & R1 & R2 & R3 \\ \hline P1 & 2 & 2 & 3 & 3 & 6 & 8 & 7 & 7 & 10 \\ P2 & 2 & 0 & 3 & 4 & 3 & 3 & & & \\ P3 & 1 & 2 & 4 & 3 & 4 & 4 & & & \\ \hline \end{array}$$i) What is the content of the Need matrix?
ii) Is the system in a safe state? If yes, justify your answer with a safe sequence.
| Process | Allocated | Maximum | Available |
|---|---|---|---|
| R1 R2 R3 | R1 R2 R3 | R1 R2 R3 | |
| P1 | 2 2 3 | 3 6 8 | 7 7 10 |
| P2 | 2 0 3 | 4 3 3 | |
| P3 | 1 2 4 | 3 4 4 |
Explain I/O buffering and discuss its importance in improving I/O performance. Describe single buffering, double buffering and circular buffering.
Explain demand paging. For given page reference string, determine the number of page faults when three page frames are available using FIFO, LRU and Optimal page replacement algorithms. Page reference string: 0, 9, 0, 1, 8, 1, 8, 7, 8, 7, 1, 2, 8, 2, 7, 8, 2, 3, 8, 3
Write short notes on any TWO: i. Critical Section Problem ii. Inter-Process Communication iii. Process State Diagram iv. Mobile Operating Systems
