Ya hemos discutido la Programación FCFS de procesos con el mismo tiempo de llegada . En esta publicación, se analizan escenarios en los que los procesos tienen tiempos de llegada diferentes. Dados n procesos con sus tiempos de ráfaga y tiempos de llegada, la tarea es encontrar el tiempo de espera promedio y el tiempo de respuesta promedio utilizando el algoritmo de programación FCFS.
FIFO simplemente pone en cola los procesos en el orden en que llegan a la cola de listos. Aquí, el proceso que viene primero se ejecutará primero y el siguiente proceso comenzará solo después de que el anterior se haya ejecutado por completo.
- Hora de finalización: Hora en la que el proceso completa su ejecución.
- Turn Around Time: Diferencia horaria entre la hora de finalización y la hora de llegada. Hora de vuelta = Hora de finalización – Hora de llegada
- Tiempo de espera (WT): diferencia de tiempo entre el tiempo de respuesta y el tiempo de ráfaga.
Tiempo de espera = Tiempo de vuelta – Tiempo de ráfaga.
Process Wait Time : Service Time - Arrival Time P0 0 - 0 = 0 P1 5 - 1 = 4 P2 8 - 2 = 6 P3 16 - 3 = 13 Average Wait Time: (0 + 4 + 6 + 13) / 4 = 5.75
Tiempo de servicio: el tiempo de servicio significa la cantidad de tiempo después del cual un proceso puede comenzar a ejecutarse. Es la suma del tiempo de ráfaga de procesos anteriores (Procesos que vinieron antes)
Cambios en el código en comparación con el código de FCFS con el mismo tiempo de llegada :
Para encontrar el tiempo de espera: tiempo que tardan todos los procesos antes de que se inicie el proceso actual (es decir, tiempo de ráfaga de todos los procesos anteriores) – tiempo de llegada del proceso actual
wait_time[i] = (bt[0] + bt[1] +…… bt[i-1] ) – hora_llegada[i]
Implementación:
1- Input the processes along with their burst time(bt) and arrival time(at) 2- Find waiting time for all other processes i.e. for a given process i: wt[i] = (bt[0] + bt[1] +...... bt[i-1]) - at[i] 3- Now find turn around time = waiting_time + burst_time for all processes 4- Average waiting time = total_waiting_time / no_of_processes 5- Average turn around time = total_turn_around_time / no_of_processes
C++
// C++ program for implementation of FCFS // scheduling with different arrival time #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 at[]) { int service_time[n]; service_time[0] = at[0]; wt[0] = 0; // calculating waiting time for (int i = 1; i < n ; i++) { // Add burst time of previous processes service_time[i] = service_time[i-1] + bt[i-1]; // Find waiting time for current process = // sum - at[i] wt[i] = service_time[i] - at[i]; // If waiting time for a process is in negative // that means it is already in the ready queue // before CPU becomes idle so its waiting time is 0 if (wt[i] < 0) wt[i] = 0; } } // 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 waiting and turn-around // times. void findavgTime(int processes[], int n, int bt[], int at[]) { int wt[n], tat[n]; // Function to find waiting time of all processes findWaitingTime(processes, n, bt, wt, at); // Function to find turn around time for all processes findTurnAroundTime(processes, n, bt, wt, tat); // Display processes along with all details cout << "Processes " << " Burst Time " << " Arrival Time " << " Waiting Time " << " Turn-Around Time " << " Completion Time \n"; int total_wt = 0, total_tat = 0; for (int i = 0 ; i < n ; i++) { total_wt = total_wt + wt[i]; total_tat = total_tat + tat[i]; int compl_time = tat[i] + at[i]; cout << " " << i+1 << "\t\t" << bt[i] << "\t\t" << at[i] << "\t\t" << wt[i] << "\t\t " << tat[i] << "\t\t " << compl_time << 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[] = {5, 9, 6}; // Arrival time of all processes int arrival_time[] = {0, 3, 6}; findavgTime(processes, n, burst_time, arrival_time); return 0; }
Java
// Java program for implementation of FCFS // scheduling with different arrival time public class GFG{ // Function to find the waiting time for all // processes static void findWaitingTime(int processes[], int n, int bt[], int wt[], int at[]) { int service_time[] = new int[n]; service_time[0] = at[0]; wt[0] = 0; // calculating waiting time for (int i = 1; i < n ; i++) { //representing wasted time in queue int wasted=0; // Add burst time of previous processes service_time[i] = service_time[i-1] + bt[i-1]; // Find waiting time for current process = // sum - at[i] wt[i] = service_time[i] - at[i]; // If waiting time for a process is in negative // that means it is already in the ready queue // before CPU becomes idle so its waiting time is 0 // wasted time is basically time for process to wait after a process is over if (wt[i] < 0) { wasted = Math.abs(wt[i]); wt[i] = 0; } //Add wasted time service_time[i] = service_time[i] + wasted; } } // Function 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]; } // Function to calculate average waiting and turn-around // times. static void findavgTime(int processes[], int n, int bt[], int at[]) { int wt[] = new int[n], tat[] = new int[n]; // Function to find waiting time of all processes findWaitingTime(processes, n, bt, wt, at); // Function to find turn around time for all processes findTurnAroundTime(processes, n, bt, wt, tat); // Display processes along with all details System.out.print("Processes " + " Burst Time " + " Arrival Time " + " Waiting Time " + " Turn-Around Time " + " Completion Time \n"); int total_wt = 0, total_tat = 0; for (int i = 0 ; i < n ; i++) { total_wt = total_wt + wt[i]; total_tat = total_tat + tat[i]; int compl_time = tat[i] + at[i]; System.out.println(i+1 + "\t\t" + bt[i] + "\t\t" + at[i] + "\t\t" + wt[i] + "\t\t " + tat[i] + "\t\t " + compl_time); } System.out.print("Average waiting time = " + (float)total_wt / (float)n); System.out.print("\nAverage turn around time = " + (float)total_tat / (float)n); } // Driver code 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[] = {5, 9, 6}; // Arrival time of all processes int arrival_time[] = {0, 3, 6}; findavgTime(processes, n, burst_time, arrival_time); } } /*This code is contributed by PrinciRaj1992*/
Python3
# Python3 program for implementation of FCFS # scheduling with different arrival time # Function to find the waiting time # for all processes def findWaitingTime(processes, n, bt, wt, at): service_time = [0] * n service_time[0] = 0 wt[0] = 0 # calculating waiting time for i in range(1, n): # Add burst time of previous processes service_time[i] = (service_time[i - 1] + bt[i - 1]) # Find waiting time for current # process = sum - at[i] wt[i] = service_time[i] - at[i] # If waiting time for a process is in # negative that means it is already # in the ready queue before CPU becomes # idle so its waiting time is 0 if (wt[i] < 0): wt[i] = 0 # Function to calculate turn around time def findTurnAroundTime(processes, n, bt, wt, tat): # Calculating turnaround time by # adding bt[i] + wt[i] 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, at): wt = [0] * n tat = [0] * n # Function to find waiting time # of all processes findWaitingTime(processes, n, bt, wt, at) # 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 Arrival Time Waiting", "Time Turn-Around Time Completion Time \n") total_wt = 0 total_tat = 0 for i in range(n): total_wt = total_wt + wt[i] total_tat = total_tat + tat[i] compl_time = tat[i] + at[i] print(" ", i + 1, "\t\t", bt[i], "\t\t", at[i], "\t\t", wt[i], "\t\t ", tat[i], "\t\t ", compl_time) print("Average waiting time = %.5f "%(total_wt /n)) print("\nAverage turn around time = ", total_tat / n) # Driver code if __name__ =="__main__": # Process id's processes = [1, 2, 3] n = 3 # Burst time of all processes burst_time = [5, 9, 6] # Arrival time of all processes arrival_time = [0, 3, 6] findavgTime(processes, n, burst_time, arrival_time) # This code is contributed # Shubham Singh(SHUBHAMSINGH10)
C#
// C# program for implementation of FCFS // scheduling with different arrival time using System; public class GFG{ // Function to find the waiting time for all // processes static void findWaitingTime(int []processes, int n, int []bt, int []wt, int []at) { int []service_time = new int[n]; service_time[0] = 0; wt[0] = 0; // calculating waiting time for (int i = 1; i < n ; i++) { // Add burst time of previous processes service_time[i] = service_time[i-1] + bt[i-1]; // Find waiting time for current process = // sum - at[i] wt[i] = service_time[i] - at[i]; // If waiting time for a process is in negative // that means it is already in the ready queue // before CPU becomes idle so its waiting time is 0 if (wt[i] < 0) wt[i] = 0; } } // Function 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]; } // Function to calculate average waiting and turn-around // times. static void findavgTime(int []processes, int n, int []bt, int []at) { int []wt = new int[n]; int []tat = new int[n]; // Function to find waiting time of all processes findWaitingTime(processes, n, bt, wt, at); // Function to find turn around time for all processes findTurnAroundTime(processes, n, bt, wt, tat); // Display processes along with all details Console.Write("Processes " + " Burst Time " + " Arrival Time " + " Waiting Time " + " Turn-Around Time " + " Completion Time \n"); int total_wt = 0, total_tat = 0; for (int i = 0 ; i < n ; i++) { total_wt = total_wt + wt[i]; total_tat = total_tat + tat[i]; int compl_time = tat[i] + at[i]; Console.WriteLine(i+1 + "\t\t" + bt[i] + "\t\t" + at[i] + "\t\t" + wt[i] + "\t\t " + tat[i] + "\t\t " + compl_time); } Console.Write("Average waiting time = " + (float)total_wt / (float)n); Console.Write("\nAverage turn around time = " + (float)total_tat / (float)n); } // Driver code 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 = {5, 9, 6}; // Arrival time of all processes int []arrival_time = {0, 3, 6}; findavgTime(processes, n, burst_time, arrival_time); } } // This code is contributed by Princi Singh
Javascript
<script> // JavaScript program for implementation of FCFS // scheduling with different arrival time // Function to find the waiting time for all // processes function findWaitingTime(processes , n , bt , wt , at) { var service_time = Array.from({length: n}, (_, i) => 0); service_time[0] = at[0]; wt[0] = 0; // calculating waiting time for (var i = 1; i < n ; i++) { //representing wasted time in queue var wasted=0; // Add burst time of previous processes service_time[i] = service_time[i-1] + bt[i-1]; // Find waiting time for current process = // sum - at[i] wt[i] = service_time[i] - at[i]; // If waiting time for a process is in negative // that means it is already in the ready queue // before CPU becomes idle so its waiting time is 0 // wasted time is basically time for process to // wait after a process is over if (wt[i] < 0) { wasted = Math.abs(wt[i]); wt[i] = 0; } // Add wasted time service_time[i] = service_time[i] + wasted; } } // Function to calculate turn around time function findTurnAroundTime(processes , n , bt, wt , tat) { // Calculating turnaround time by adding bt[i] + wt[i] for (var i = 0; i < n ; i++) tat[i] = bt[i] + wt[i]; } // Function to calculate average waiting and turn-around // times. function findavgTime(processes , n , bt , at) { var wt = Array.from({length: n}, (_, i) => 0.0); var tat = Array.from({length: n}, (_, i) => 0.0); // Function to find waiting time of all processes findWaitingTime(processes, n, bt, wt, at); // 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 " + " Arrival Time " + " Waiting Time " + " Turn-Around Time " + " Completion Time <br>"); var total_wt = 0, total_tat = 0; for (var i = 0 ; i < n ; i++) { total_wt = total_wt + wt[i]; total_tat = total_tat + tat[i]; var compl_time = tat[i] + at[i]; document.write(i+1 + " " + bt[i] + " " + at[i] + " " + wt[i] + " " + tat[i] + " " + compl_time+"<br>"); } document.write("<br>Average waiting time = " + total_wt/n +"<br>"); document.write("<br>Average turn around time = " + total_tat/n+"<br>"); } // Driver code // Process id's var processes = [1, 2, 3]; var n = processes.length; // Burst time of all processes var burst_time = [5, 9, 6]; // Arrival time of all processes var arrival_time = [0, 3, 6]; findavgTime(processes, n, burst_time, arrival_time); // This code is contributed by 29AjayKumar </script>
Producción:
Processes Burst Time Arrival Time Waiting Time Turn-Around Time Completion Time 1 5 0 0 5 5 2 9 3 2 11 14 3 6 6 8 14 20 Average waiting time = 3.33333 Average turn around time = 10.0
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Artículo escrito por GeeksforGeeks-1 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA