Mamurov muslimbek cse213 ca#9 unique id: 22301T001 transfer student

MAMUROV MUSLIMBEK CSE213 CA#9 unique id:22301T001 transfer student

1. 
   What is the round robin scheduling
   

Round-robin scheduling is a CPU scheduling algorithm used by operating systems to allocate CPU time to multiple processes or threads in a fair and balanced manner. It is a preemptive scheduling algorithm that provides each process or thread with an equal share of CPU time in a cyclic manner.

In round-robin scheduling, processes are assigned a fixed time quantum or time slice. The scheduler maintains a queue of ready processes, and each process is allowed to execute for a time slice before being preempted and moved to the end of the queue. The scheduler then selects the next process in the queue to execute and repeats the process.

The key characteristic of round-robin scheduling is that it provides fairness by ensuring that no process or thread monopolizes the CPU for an extended period. Each process gets an equal chance to execute, and the time quantum ensures that no process can hog the CPU indefinitely.

Round-robin scheduling is commonly used in time-sharing systems where multiple users or applications share a single CPU. It provides reasonable response time and allows for concurrent execution of multiple tasks. However, it may not be the most efficient scheduling algorithm in scenarios where the time quantum is too short or when processes have highly varying CPU burst times.

2.Explain taking a example

Suppose we have three processes, P1, P2, and P3, and each process is assigned a time quantum of 2 units. The processes arrive in the order P1, P2, P3.

Here is the timeline of their execution using round-robin scheduling:

Time 0: All processes are in the ready queue.

1.Ready Queue: [P1, P2, P3]

Currently executing process: None
Time 0-2: Process P1 is scheduled and executes for 2 units.

2.Ready Queue: [P2, P3, P1]

Currently executing process: P1
Time 2-4: Process P2 is scheduled and executes for 2 units.

3.Ready Queue: [P3, P1, P2]

Currently executing process: P2
Time 4-6: Process P3 is scheduled and executes for 2 units.

4.Ready Queue: [P1, P2, P3]

Currently executing process: P3
Time 6-8: Process P1 is scheduled and executes for 2 units.

5.Ready Queue: [P2, P3, P1]

Currently executing process: P1
Time 8-10: Process P2 is scheduled and executes for 2 units.

6.Ready Queue: [P3, P1, P2]

Currently executing process: P2
Time 10-12: Process P3 is scheduled and executes for 2 units.

7.Ready Queue: [P1, P2, P3]

Currently executing process: P3
Time 12-14: Process P1 is scheduled and executes for 2 units.

8.Ready Queue: [P2, P3, P1]

Currently executing process: P1
Time 14-16: Process P2 is scheduled and executes for 2 units.

9.Ready Queue: [P3, P1, P2]

Currently executing process: P2
Time 16-18: Process P3 is scheduled and executes for 2 units.

10.Ready Queue: [P1, P2, P3]

Currently executing process: P3
The process execution continues in this round-robin fashion until all processes complete their execution.

In this example, each process gets an equal share of CPU time, and no process monopolizes the CPU for an extended period. The time quantum of 2 units ensures that each process gets a fair chance to execute before being preempted.

Round-robin scheduling provides fairness and allows for concurrent execution of processes, making it suitable for time-sharing systems where multiple users or applications need to share the CPU resources.

If yes, then explain

If you have a single-user system with multiple concurrent tasks or threads, round-robin scheduling can still be useful to provide fairness and responsiveness among those tasks.

In a single-user system, you might have multiple applications or background tasks running simultaneously. Round-robin scheduling can ensure that each task receives its fair share of CPU time, preventing any single task from monopolizing the CPU and allowing all tasks to make progress.

Here's an example to illustrate the usefulness of round-robin scheduling in a single-user system:

Suppose you have a single-user system with three running tasks: Task A, Task B, and Task C. The tasks are assigned a time quantum of 10 milliseconds.

Time 0: All tasks are ready to run.

Ready Queue: [Task A, Task B, Task C]

Currently executing task: None
Time 0-10: Task A is scheduled and executes for 10 milliseconds.

Ready Queue: [Task B, Task C, Task A]

Currently executing task: Task A
Time 10-20: Task B is scheduled and executes for 10 milliseconds.

Ready Queue: [Task C, Task A, Task B]

Currently executing task: Task B
Time 20-30: Task C is scheduled and executes for 10 milliseconds.

Ready Queue: [Task A, Task B, Task C]

Currently executing task: Task C
Time 30-40: Task A is scheduled again and executes for 10 milliseconds.

Ready Queue: [Task B, Task C, Task A]

Currently executing task: Task A
The round-robin scheduling continues in this manner, providing each task with its fair share of CPU time and allowing them to make progress.


Even in a single-user system, round-robin scheduling can be useful when you have multiple concurrent tasks or threads that need to share the CPU. It ensures that all tasks receive CPU time regularly, preventing any single task from starving and maintaining a responsive system.