What Is Round Robin In OS, Explanation, Source Code, Steps

December 18, 2022December 18, 2022 CS Electrical And Electronics

Hello guys, welcome back to our blog. Here in this article, we will discuss what is round robin in an operating system (OS), why a round robin is needed, steps to implement the round robin algorithm, and the source code of round robin in C.

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What Is Round Robin In OS

Round Robin is a scheduling algorithm that is used to allocate a set of resources, such as time or processing power, among a number of tasks or processes. It works by assigning each task or process a fixed time slice or “quantum” of resources, and rotating through the tasks or processes in a cyclical manner, giving each one a chance to use the resources before moving on to the next one. This allows each task or process to be executed in turn, ensuring that all of the tasks or processes receive a fair share of the resources.

Round Robin scheduling is often used in real-time operating systems, where it is important to ensure that all tasks or processes are given a chance to run in a timely manner. It is also used in other settings where it is important to allocate resources fairly and efficiently, such as in computer networks and in resource allocation for distributed systems.

Why round robin is needed?

Round Robin scheduling is a method of allocating resources, such as time or processing power, among a number of tasks or processes. It is used to ensure that all tasks or processes receive a fair share of the resources and are given the opportunity to run in a timely manner.

Round Robin scheduling is often used in real-time operating systems, where it is important to ensure that all tasks or processes are given the chance to run in a timely manner and that the system can respond quickly to changes in resource needs. It is also used in other settings where it is important to allocate resources fairly and efficiently, such as in computer networks and in resource allocation for distributed systems.

Overall, the use of Round Robin scheduling can help to improve the performance and efficiency of a system by ensuring that tasks or processes are given the resources they need to run in a timely and fair manner.

Steps to implement round robin?

Here is an example of how the Round Robin scheduling algorithm might be implemented in an operating system in pseudocode:

function RoundRobin(tasks, quantum):
  while there are tasks to be executed:
    for each task in tasks:
      if task has not completed:
        execute task for quantum time units
        if task has not completed:
          add task to the end of the tasks list
      else:
        remove task from tasks list
  return

This pseudocode shows a simple implementation of the Round Robin algorithm, which rotates through a list of tasks, executing each one for a fixed time quantum before moving on to the next one. If a task has not been completed after its time quantum has expired, it is added back to the end of the list to be executed again later. Tasks that have been completed are removed from the list.

It’s important to note that this is just one example of how the Round Robin algorithm might be implemented, and the specific details of the implementation will depend on the specific requirements and constraints of the operating system.

Source code for round-robin process scheduling in C

Here is an example of how the Round Robin scheduling algorithm might be implemented in a programming language such as C:

#include <stdio.h>
#include <stdbool.h>

#define MAX_TASKS 10
#define QUANTUM 10

typedef struct {
  char name[32];
  int arrival_time;
  int execution_time;
  int remaining_time;
} Task;

int main(int argc, char** argv) {
  Task tasks[MAX_TASKS];
  int num_tasks = 0;
  int elapsed_time = 0;
  
  // Read in tasks from input
  while (scanf("%s %d %d", tasks[num_tasks].name, &tasks[num_tasks].arrival_time, &tasks[num_tasks].execution_time) == 3) {
    tasks[num_tasks].remaining_time = tasks[num_tasks].execution_time;
    num_tasks++;
  }
  
  // Execute tasks using Round Robin scheduling
  while (true) {
    bool any_tasks_left = false;
    for (int i = 0; i < num_tasks; i++) {
      if (tasks[i].remaining_time > 0) {
        any_tasks_left = true;
        if (tasks[i].arrival_time <= elapsed_time) {
          printf("Executing %s for %d time units\n", tasks[i].name, QUANTUM);
          tasks[i].remaining_time -= QUANTUM;
          elapsed_time += QUANTUM;
        }
      }
    }
    if (!any_tasks_left) {
      break;
    }
  }
  
  return 0;
}

This C program implements the Round Robin scheduling algorithm to execute a set of tasks. The tasks are read in from input, and the program executes each task for a fixed time quantum (in this case, 10-time units) using a loop. If a task has not been completed after its time quantum has expired, it is added back to the list of tasks to be executed again later. The program continues to execute tasks until there are no more tasks left to execute.

Advantages of round-robin process scheduling

Round Robin is a popular scheduling algorithm because it has several advantages, including:

Fairness: One of the main advantages of Round Robin scheduling is that it is fair to all tasks or processes. Each task or process is given a fixed time slice or “quantum” of resources, and all tasks or processes are given an equal opportunity to use the resources. This helps to ensure that all tasks or processes receive a fair share of the resources and are able to run in a timely manner.
Simplicity: Round Robin scheduling is relatively simple to implement and understand, which makes it a popular choice in many situations. It is easy to implement using a simple loop that rotates through the tasks or processes, giving each one a chance to use the resources before moving on to the next one.
Responsiveness: Round Robin scheduling allows the operating system to respond quickly to changes in resource needs, as it can preemptively interrupt a running task or process and allocate resources to another task or process if necessary. This can be particularly useful in real-time operating systems, where it is important to ensure that all tasks or processes are given the chance to run in a timely manner.
Efficient resource utilization: Round Robin scheduling can help to optimize the use of resources by allowing the operating system to allocate resources to the tasks or processes that need them most at any given time. This can help to improve the overall performance and efficiency of the system.
Good for short tasks: Round Robin scheduling is well-suited for systems where there are a large number of short tasks or processes that need to be executed. Since each task or process is given a fixed time quantum to use, the algorithm can ensure that all tasks or processes are given a fair opportunity to run without causing undue delays.

Disadvantages of round-robin process scheduling

While Round Robin scheduling has several advantages, it also has a few potential disadvantages, including:

Overhead: One potential disadvantage of Round Robin scheduling is that it can incur overhead costs due to the need to constantly switch between tasks or processes. This can result in decreased performance and efficiency, particularly in systems with a large number of tasks or processes.
Poor performance for long tasks: Round Robin scheduling may not be as efficient for systems with a small number of long-running tasks or processes. In these cases, the constant switching between tasks may lead to increased delays and decreased overall system performance.
Limited control: Round Robin scheduling provides limited control over the allocation of resources, as it simply assigns a fixed time quantum to each task or process. This can make it difficult to prioritize certain tasks or processes and allocate resources to them more effectively.
Limited predictability: The performance of Round Robin scheduling can be difficult to predict, as it can be affected by a variety of factors such as the length and complexity of the tasks or processes being executed, the number of tasks or processes, and the size of the time quantum. This can make it difficult to determine the optimal settings for the algorithm in a given system.

Applications of round-robin process scheduling

Round Robin scheduling is widely used in a variety of applications, including:

Real-time operating systems: Round Robin scheduling is often used in real-time operating systems, where it is important to ensure that all tasks or processes are given the chance to run in a timely manner and that the system can respond quickly to changes in resource needs.
Computer networks: Round Robin scheduling is used in some computer networks to allocate bandwidth and other resources to different devices or users in a fair and efficient manner.
Distributed systems: Round Robin scheduling is often used in resource allocation for distributed systems, where it is important to allocate resources fairly and efficiently among different nodes or devices.
Multiprocessor systems: Round Robin scheduling is used in some multiprocessor systems to allocate processing power and other resources to different tasks or processes.
Cloud computing: Round Robin scheduling is also used in some cloud computing systems to allocate resources such as computing power and storage to different users or applications.

Overall, Round Robin scheduling is a widely used algorithm that is well-suited for a variety of applications where it is important to allocate resources fairly and efficiently.

This was about “What Is Round Robin In OS“. I hope this article may help you all a lot. Thank you for reading.

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