Round Robin es un algoritmo de programación de CPU en el que a cada proceso se le asigna un intervalo de tiempo fijo de forma cíclica. Es básicamente la versión preventiva del algoritmo de programación de CPU por orden de llegada .
- El algoritmo de CPU Round Robin generalmente se enfoca en la técnica de tiempo compartido.
- El período de tiempo durante el cual se permite que un proceso o trabajo se ejecute en un método preventivo se denomina cantidad de tiempo .
- A cada proceso o trabajo presente en la cola de espera se le asigna la CPU para ese tiempo, si la ejecución del proceso se completa durante ese tiempo, el proceso finalizará ; de lo contrario, el proceso volverá a la mesa de espera y esperará el siguiente . gire para completar la ejecución.
Características del algoritmo de programación de CPU Round Robin:
- Es simple, fácil de implementar y libre de hambre, ya que todos los procesos obtienen una parte justa de la CPU.
- Una de las técnicas más utilizadas en la programación de CPU como núcleo.
- Es preventivo ya que a los procesos se les asigna CPU solo durante un período de tiempo fijo como máximo.
- La desventaja de esto es más gastos generales de cambio de contexto.
Ventajas del algoritmo de programación de CPU Round Robin:
- Hay equidad ya que cada proceso obtiene la misma parte de la CPU.
- El proceso recién creado se agrega al final de la cola lista.
- Un planificador de turnos generalmente emplea el tiempo compartido, dando a cada trabajo un intervalo de tiempo o cantidad.
- Al realizar una programación por turnos, se asigna una cantidad de tiempo particular a diferentes trabajos.
- Cada proceso tiene la oportunidad de reprogramarse después de un tiempo cuántico particular en esta programación.
Desventajas del algoritmo de programación de CPU Round Robin:
- Hay mayor tiempo de espera y tiempo de respuesta.
- Hay un rendimiento bajo.
- Hay cambios de contexto.
- El diagrama de Gantt parece ser demasiado grande (si el tiempo cuántico es menor para la programación. Por ejemplo: 1 ms para una programación grande).
- Programación que requiere mucho tiempo para pequeños cuantos.
Ejemplos para mostrar el funcionamiento del algoritmo de programación Round Robin :
Ejemplo-1: considere la siguiente tabla de tiempo de llegada y tiempo de ráfaga para cinco procesos P1, P2, P3 y P4 y dado Time Quantum = 2
C++
// C++ program for implementation of RR scheduling
#include<iostream>
using namespace std;
// Function to find the waiting time for all
// processes
void findWaitingTime(int processes[], int n,
int bt[], int wt[], int quantum)
{
// Make a copy of burst times bt[] to store remaining
// burst times.
int rem_bt[n];
for (int i = 0 ; i < n ; i++)
rem_bt[i] = bt[i];
int t = 0; // Current time
// Keep traversing processes in round robin manner
// until all of them are not done.
while (1)
{
bool done = true;
// Traverse all processes one by one repeatedly
for (int i = 0 ; i < n; i++)
{
// If burst time of a process is greater than 0
// then only need to process further
if (rem_bt[i] > 0)
{
done = false; // There is a pending process
if (rem_bt[i] > quantum)
{
// Increase the value of t i.e. shows
// how much time a process has been processed
t += quantum;
// Decrease the burst_time of current process
// by quantum
rem_bt[i] -= quantum;
}
// If burst time is smaller than or equal to
// quantum. Last cycle for this process
else
{
// Increase the value of t i.e. shows
// how much time a process has been processed
t = t + rem_bt[i];
// Waiting time is current time minus time
// used by this process
wt[i] = t - bt[i];
// As the process gets fully executed
// make its remaining burst time = 0
rem_bt[i] = 0;
}
}
}
// If all processes are done
if (done == true)
break;
}
}
// Function to calculate turn around time
void findTurnAroundTime(int processes[], int n,
int bt[], int wt[], int tat[])
{
// calculating turnaround time by adding
// bt[i] + wt[i]
for (int i = 0; i < n ; i++)
tat[i] = bt[i] + wt[i];
}
// Function to calculate average time
void findavgTime(int processes[], int n, int bt[],
int quantum)
{
int wt[n], tat[n], total_wt = 0, total_tat = 0;
// Function to find waiting time of all processes
findWaitingTime(processes, n, bt, wt, quantum);
// Function to find turn around time for all processes
findTurnAroundTime(processes, n, bt, wt, tat);
// Display processes along with all details
cout << "PN\t "<< " \tBT "
<< " WT " << " \tTAT\n";
// Calculate total waiting time and total turn
// around time
for (int i=0; i<n; i++)
{
total_wt = total_wt + wt[i];
total_tat = total_tat + tat[i];
cout << " " << i+1 << "\t\t" << bt[i] <<"\t "
<< wt[i] <<"\t\t " << tat[i] <<endl;
}
cout << "Average waiting time = "
<< (float)total_wt / (float)n;
cout << "\nAverage turn around time = "
<< (float)total_tat / (float)n;
}
// Driver code
int main()
{
// process id's
int processes[] = { 1, 2, 3};
int n = sizeof processes / sizeof processes[0];
// Burst time of all processes
int burst_time[] = {10, 5, 8};
// Time quantum
int quantum = 2;
findavgTime(processes, n, burst_time, quantum);
return 0;
}
Java
// Java program for implementation of RR scheduling
public class GFG
{
// Method to find the waiting time for all
// processes
static void findWaitingTime(int processes[], int n,
int bt[], int wt[], int quantum)
{
// Make a copy of burst times bt[] to store remaining
// burst times.
int rem_bt[] = new int[n];
for (int i = 0 ; i < n ; i++)
rem_bt[i] = bt[i];
int t = 0; // Current time
// Keep traversing processes in round robin manner
// until all of them are not done.
while(true)
{
boolean done = true;
// Traverse all processes one by one repeatedly
for (int i = 0 ; i < n; i++)
{
// If burst time of a process is greater than 0
// then only need to process further
if (rem_bt[i] > 0)
{
done = false; // There is a pending process
if (rem_bt[i] > quantum)
{
// Increase the value of t i.e. shows
// how much time a process has been processed
t += quantum;
// Decrease the burst_time of current process
// by quantum
rem_bt[i] -= quantum;
}
// If burst time is smaller than or equal to
// quantum. Last cycle for this process
else
{
// Increase the value of t i.e. shows
// how much time a process has been processed
t = t + rem_bt[i];
// Waiting time is current time minus time
// used by this process
wt[i] = t - bt[i];
// As the process gets fully executed
// make its remaining burst time = 0
rem_bt[i] = 0;
}
}
}
// If all processes are done
if (done == true)
break;
}
}
// Method to calculate turn around time
static void findTurnAroundTime(int processes[], int n,
int bt[], int wt[], int tat[])
{
// calculating turnaround time by adding
// bt[i] + wt[i]
for (int i = 0; i < n ; i++)
tat[i] = bt[i] + wt[i];
}
// Method to calculate average time
static void findavgTime(int processes[], int n, int bt[],
int quantum)
{
int wt[] = new int[n], tat[] = new int[n];
int total_wt = 0, total_tat = 0;
// Function to find waiting time of all processes
findWaitingTime(processes, n, bt, wt, quantum);
// Function to find turn around time for all processes
findTurnAroundTime(processes, n, bt, wt, tat);
// Display processes along with all details
System.out.println("PN " + " B " +
" WT " + " TAT");
// Calculate total waiting time and total turn
// around time
for (int i=0; i<n; i++)
{
total_wt = total_wt + wt[i];
total_tat = total_tat + tat[i];
System.out.println(" " + (i+1) + "\t\t" + bt[i] +"\t " +
wt[i] +"\t\t " + tat[i]);
}
System.out.println("Average waiting time = " +
(float)total_wt / (float)n);
System.out.println("Average turn around time = " +
(float)total_tat / (float)n);
}
// Driver Method
public static void main(String[] args)
{
// process id's
int processes[] = { 1, 2, 3};
int n = processes.length;
// Burst time of all processes
int burst_time[] = {10, 5, 8};
// Time quantum
int quantum = 2;
findavgTime(processes, n, burst_time, quantum);
}
}
Python3
# Python3 program for implementation of
# RR scheduling
# Function to find the waiting time
# for all processes
def findWaitingTime(processes, n, bt,
wt, quantum):
rem_bt = [0] * n
# Copy the burst time into rt[]
for i in range(n):
rem_bt[i] = bt[i]
t = 0 # Current time
# Keep traversing processes in round
# robin manner until all of them are
# not done.
while(1):
done = True
# Traverse all processes one by
# one repeatedly
for i in range(n):
# If burst time of a process is greater
# than 0 then only need to process further
if (rem_bt[i] > 0) :
done = False # There is a pending process
if (rem_bt[i] > quantum) :
# Increase the value of t i.e. shows
# how much time a process has been processed
t += quantum
# Decrease the burst_time of current
# process by quantum
rem_bt[i] -= quantum
# If burst time is smaller than or equal
# to quantum. Last cycle for this process
else:
# Increase the value of t i.e. shows
# how much time a process has been processed
t = t + rem_bt[i]
# Waiting time is current time minus
# time used by this process
wt[i] = t - bt[i]
# As the process gets fully executed
# make its remaining burst time = 0
rem_bt[i] = 0
# If all processes are done
if (done == True):
break
# Function to calculate turn around time
def findTurnAroundTime(processes, n, bt, wt, tat):
# Calculating turnaround time
for i in range(n):
tat[i] = bt[i] + wt[i]
# Function to calculate average waiting
# and turn-around times.
def findavgTime(processes, n, bt, quantum):
wt = [0] * n
tat = [0] * n
# Function to find waiting time
# of all processes
findWaitingTime(processes, n, bt,
wt, quantum)
# Function to find turn around time
# for all processes
findTurnAroundTime(processes, n, bt,
wt, tat)
# Display processes along with all details
print("Processes Burst Time Waiting",
"Time Turn-Around Time")
total_wt = 0
total_tat = 0
for i in range(n):
total_wt = total_wt + wt[i]
total_tat = total_tat + tat[i]
print(" ", i + 1, "\t\t", bt[i],
"\t\t", wt[i], "\t\t", tat[i])
print("\nAverage waiting time = %.5f "%(total_wt /n) )
print("Average turn around time = %.5f "% (total_tat / n))
# Driver code
if __name__ =="__main__":
# Process id's
proc = [1, 2, 3]
n = 3
# Burst time of all processes
burst_time = [10, 5, 8]
# Time quantum
quantum = 2;
findavgTime(proc, n, burst_time, quantum)
# This code is contributed by
# Shubham Singh(SHUBHAMSINGH10)
C#
// C# program for implementation of RR
// scheduling
using System;
public class GFG {
// Method to find the waiting time
// for all processes
static void findWaitingTime(int []processes,
int n, int []bt, int []wt, int quantum)
{
// Make a copy of burst times bt[] to
// store remaining burst times.
int []rem_bt = new int[n];
for (int i = 0 ; i < n ; i++)
rem_bt[i] = bt[i];
int t = 0; // Current time
// Keep traversing processes in round
// robin manner until all of them are
// not done.
while(true)
{
bool done = true;
// Traverse all processes one by
// one repeatedly
for (int i = 0 ; i < n; i++)
{
// If burst time of a process
// is greater than 0 then only
// need to process further
if (rem_bt[i] > 0)
{
// There is a pending process
done = false;
if (rem_bt[i] > quantum)
{
// Increase the value of t i.e.
// shows how much time a process
// has been processed
t += quantum;
// Decrease the burst_time of
// current process by quantum
rem_bt[i] -= quantum;
}
// If burst time is smaller than
// or equal to quantum. Last cycle
// for this process
else
{
// Increase the value of t i.e.
// shows how much time a process
// has been processed
t = t + rem_bt[i];
// Waiting time is current
// time minus time used by
// this process
wt[i] = t - bt[i];
// As the process gets fully
// executed make its remaining
// burst time = 0
rem_bt[i] = 0;
}
}
}
// If all processes are done
if (done == true)
break;
}
}
// Method to calculate turn around time
static void findTurnAroundTime(int []processes,
int n, int []bt, int []wt, int []tat)
{
// calculating turnaround time by adding
// bt[i] + wt[i]
for (int i = 0; i < n ; i++)
tat[i] = bt[i] + wt[i];
}
// Method to calculate average time
static void findavgTime(int []processes, int n,
int []bt, int quantum)
{
int []wt = new int[n];
int []tat = new int[n];
int total_wt = 0, total_tat = 0;
// Function to find waiting time of
// all processes
findWaitingTime(processes, n, bt, wt, quantum);
// Function to find turn around time
// for all processes
findTurnAroundTime(processes, n, bt, wt, tat);
// Display processes along with
// all details
Console.WriteLine("Processes " + " Burst time " +
" Waiting time " + " Turn around time");
// Calculate total waiting time and total turn
// around time
for (int i = 0; i < n; i++)
{
total_wt = total_wt + wt[i];
total_tat = total_tat + tat[i];
Console.WriteLine(" " + (i+1) + "\t\t" + bt[i]
+ "\t " + wt[i] +"\t\t " + tat[i]);
}
Console.WriteLine("Average waiting time = " +
(float)total_wt / (float)n);
Console.Write("Average turn around time = " +
(float)total_tat / (float)n);
}
// Driver Method
public static void Main()
{
// process id's
int []processes = { 1, 2, 3};
int n = processes.Length;
// Burst time of all processes
int []burst_time = {10, 5, 8};
// Time quantum
int quantum = 2;
findavgTime(processes, n, burst_time, quantum);
}
}
// This code is contributed by nitin mittal.
Javascript
<script>
// JavaScript program for implementation of RR scheduling
// Function to find the waiting time for all
// processes
const findWaitingTime = (processes, n, bt, wt, quantum) => {
// Make a copy of burst times bt[] to store remaining
// burst times.
let rem_bt = new Array(n).fill(0);
for (let i = 0; i < n; i++)
rem_bt[i] = bt[i];
let t = 0; // Current time
// Keep traversing processes in round robin manner
// until all of them are not done.
while (1) {
let done = true;
// Traverse all processes one by one repeatedly
for (let i = 0; i < n; i++) {
// If burst time of a process is greater than 0
// then only need to process further
if (rem_bt[i] > 0) {
done = false; // There is a pending process
if (rem_bt[i] > quantum) {
// Increase the value of t i.e. shows
// how much time a process has been processed
t += quantum;
// Decrease the burst_time of current process
// by quantum
rem_bt[i] -= quantum;
}
// If burst time is smaller than or equal to
// quantum. Last cycle for this process
else {
// Increase the value of t i.e. shows
// how much time a process has been processed
t = t + rem_bt[i];
// Waiting time is current time minus time
// used by this process
wt[i] = t - bt[i];
// As the process gets fully executed
// make its remaining burst time = 0
rem_bt[i] = 0;
}
}
}
// If all processes are done
if (done == true)
break;
}
}
// Function to calculate turn around time
const findTurnAroundTime = (processes, n, bt, wt, tat) => {
// calculating turnaround time by adding
// bt[i] + wt[i]
for (let i = 0; i < n; i++)
tat[i] = bt[i] + wt[i];
}
// Function to calculate average time
const findavgTime = (processes, n, bt, quantum) => {
let wt = new Array(n).fill(0), tat = new Array(n).fill(0);
let total_wt = 0, total_tat = 0;
// Function to find waiting time of all processes
findWaitingTime(processes, n, bt, wt, quantum);
// Function to find turn around time for all processes
findTurnAroundTime(processes, n, bt, wt, tat);
// Display processes along with all details
document.write(`Processes Burst time Waiting time Turn around time<br/>`);
// Calculate total waiting time and total turn
// around time
for (let i = 0; i < n; i++) {
total_wt = total_wt + wt[i];
total_tat = total_tat + tat[i];
document.write(`${i + 1} ${bt[i]} ${wt[i]} ${tat[i]}<br/>`);
}
document.write(`Average waiting time = ${total_wt / n}`);
document.write(`<br/>Average turn around time = ${total_tat / n}`);
}
// Driver code
// process id's
processes = [1, 2, 3];
let n = processes.length;
// Burst time of all processes
let burst_time = [10, 5, 8];
// Time quantum
let quantum = 2;
findavgTime(processes, n, burst_time, quantum);
// This code is contributed by rakeshsahni
</script>
Publicación traducida automáticamente
Artículo escrito por GeeksforGeeks-1 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA