Prerequisite – Program for Priority Scheduling – Set 1
Priority scheduling is a non-preemptive algorithm and one of the most common scheduling algorithms in batch systems. Each process is assigned first arrival time (less arrival time process first) if two processes have same arrival time, then compare to priorities (highest process first). Also, if two processes have same priority then compare to process number (less process number first). This process is repeated while all process get executed.
Implementation –
- First input the processes with their arrival time, burst time and priority.
- First process will schedule, which have the lowest arrival time, if two or more processes will have lowest arrival time, then whoever has higher priority will schedule first.
- Now further processes will be schedule according to the arrival time and priority of the process. (Here we are assuming that lower the priority number having higher priority). If two process priority are same then sort according to process number.
Note: In the question, They will clearly mention, which number will have higher priority and which number will have lower priority. - Once all the processes have been arrived, we can schedule them based on their priority.
Gantt Chart –
Examples –
Input : process no-> 1 2 3 4 5 arrival time-> 0 1 3 2 4 burst time-> 3 6 1 2 4 priority-> 3 4 9 7 8 Output : Process_no arrival_time Burst_time Complete_time Turn_Around_Time Waiting_Time 1 0 3 3 3 0 2 1 6 9 8 2 3 3 1 16 13 12 4 2 2 11 9 7 5 4 4 15 11 7 Average Waiting Time is : 5.6 Average Turn Around time is : 8.8
C++
// C++ implementation for Priority Scheduling with//Different Arrival Time priority scheduling/*1. sort the processes according to arrival time2. if arrival time is same the acc to priority3. apply fcfs*/#include <bits/stdc++.h>using namespace std;#define totalprocess 5// Making a struct to hold the given inputstruct process{int at,bt,pr,pno;};process proc[50];/*Writing comparator function to sort according to priority ifarrival time is same*/bool comp(process a,process b){if(a.at == b.at){return a.pr<b.pr;}else{ return a.at<b.at;}}// Using FCFS Algorithm to find Waiting timevoid get_wt_time(int wt[]){// declaring service array that stores cumulative burst timeint service[50];// Initialising initial elements of the arraysservice[0] = proc[0].at;wt[0]=0;for(int i=1;i<totalprocess;i++){service[i]=proc[i-1].bt+service[i-1];wt[i]=service[i]-proc[i].at;// If waiting time is negative, change it into zero if(wt[i]<0) { wt[i]=0; }}}void get_tat_time(int tat[],int wt[]){// Filling turnaroundtime arrayfor(int i=0;i<totalprocess;i++){ tat[i]=proc[i].bt+wt[i];} }void findgc(){//Declare waiting time and turnaround time arrayint wt[50],tat[50];double wavg=0,tavg=0;// Function call to find waiting time arrayget_wt_time(wt);//Function call to find turnaround timeget_tat_time(tat,wt); int stime[50],ctime[50];stime[0] = proc[0].at;ctime[0]=stime[0]+tat[0];// calculating starting and ending timefor(int i=1;i<totalprocess;i++) { stime[i]=ctime[i-1]; ctime[i]=stime[i]+tat[i]-wt[i]; } cout<<"Process_no\tStart_time\tComplete_time\tTurn_Around_Time\tWaiting_Time"<<endl; // display the process details for(int i=0;i<totalprocess;i++) { wavg += wt[i]; tavg += tat[i]; cout<<proc[i].pno<<"\t\t"<< stime[i]<<"\t\t"<<ctime[i]<<"\t\t"<< tat[i]<<"\t\t\t"<<wt[i]<<endl; } // display the average waiting time //and average turn around time cout<<"Average waiting time is : "; cout<<wavg/(float)totalprocess<<endl; cout<<"average turnaround time : "; cout<<tavg/(float)totalprocess<<endl;}int main(){int arrivaltime[] = { 1, 2, 3, 4, 5 };int bursttime[] = { 3, 5, 1, 7, 4 };int priority[] = { 3, 4, 1, 7, 8 }; for(int i=0;i<totalprocess;i++){ proc[i].at=arrivaltime[i]; proc[i].bt=bursttime[i]; proc[i].pr=priority[i]; proc[i].pno=i+1; } //Using inbuilt sort function sort(proc,proc+totalprocess,comp); //Calling function findgc for finding Gantt Chart findgc(); return 0;}// This code is contributed by Anukul Chand. |
Java
// Java implementation for Priority Scheduling with//Different Arrival Time priority schedulingimport java.util.*;/// Data Structureclass Process { int at, bt, pri, pno; Process(int pno, int at, int bt, int pri) { this.pno = pno; this.pri = pri; this.at = at; this.bt = bt; }}/// Gantt chart structureclass GChart { // process number, start time, complete time, // turn around time, waiting time int pno, stime, ctime, wtime, ttime;}// user define comparative method (first arrival first serve,// if arrival time same then heigh priority first)class MyComparator implements Comparator { public int compare(Object o1, Object o2) { Process p1 = (Process)o1; Process p2 = (Process)o2; if (p1.at < p2.at) return (-1); else if (p1.at == p2.at && p1.pri > p2.pri) return (-1); else return (1); }}// class to find Gantt chartclass FindGantChart { void findGc(LinkedList queue) { // initial time = 0 int time = 0; // priority Queue sort data according // to arrival time or priority (ready queue) TreeSet prique = new TreeSet(new MyComparator()); // link list for store processes data LinkedList result = new LinkedList(); // process in ready queue from new state queue while (queue.size() > 0) prique.add((Process)queue.removeFirst()); Iterator it = prique.iterator(); // time set to according to first process time = ((Process)prique.first()).at; // scheduling process while (it.hasNext()) { // dispatcher dispatch the // process ready to running state Process obj = (Process)it.next(); GChart gc1 = new GChart(); gc1.pno = obj.pno; gc1.stime = time; time += obj.bt; gc1.ctime = time; gc1.ttime = gc1.ctime - obj.at; gc1.wtime = gc1.ttime - obj.bt; /// store the exxtreted process result.add(gc1); } // create object of output class and call method new ResultOutput(result); }} |
Python3
# Python3 implementation for Priority Scheduling with# Different Arrival Time priority scheduling"""1. sort the processes according to arrival time 2. if arrival time is same the acc to priority 3. apply fcfs """ totalprocess = 5proc = []for i in range(5): l = [] for j in range(4): l.append(0) proc.append(l)# Using FCFS Algorithm to find Waiting timedef get_wt_time( wt): # declaring service array that stores # cumulative burst time service = [0] * 5 # Initialising initial elements # of the arrays service[0] = 0 wt[0] = 0 for i in range(1, totalprocess): service[i] = proc[i - 1][1] + service[i - 1] wt[i] = service[i] - proc[i][0] + 1 # If waiting time is negative, # change it o zero if(wt[i] < 0) : wt[i] = 0 def get_tat_time(tat, wt): # Filling turnaroundtime array for i in range(totalprocess): tat[i] = proc[i][1] + wt[i]def findgc(): # Declare waiting time and # turnaround time array wt = [0] * 5 tat = [0] * 5 wavg = 0 tavg = 0 # Function call to find waiting time array get_wt_time(wt) # Function call to find turnaround time get_tat_time(tat, wt) stime = [0] * 5 ctime = [0] * 5 stime[0] = 1 ctime[0] = stime[0] + tat[0] # calculating starting and ending time for i in range(1, totalprocess): stime[i] = ctime[i - 1] ctime[i] = stime[i] + tat[i] - wt[i] print("Process_no\tStart_time\tComplete_time", "\tTurn_Around_Time\tWaiting_Time") # display the process details for i in range(totalprocess): wavg += wt[i] tavg += tat[i] print(proc[i][3], "\t\t", stime[i], "\t\t", end = " ") print(ctime[i], "\t\t", tat[i], "\t\t\t", wt[i]) # display the average waiting time # and average turn around time print("Average waiting time is : ", end = " ") print(wavg / totalprocess) print("average turnaround time : " , end = " ") print(tavg / totalprocess)# Driver codeif __name__ =="__main__": arrivaltime = [1, 2, 3, 4, 5] bursttime = [3, 5, 1, 7, 4] priority = [3, 4, 1, 7, 8] for i in range(totalprocess): proc[i][0] = arrivaltime[i] proc[i][1] = bursttime[i] proc[i][2] = priority[i] proc[i][3] = i + 1 # Using inbuilt sort function proc = sorted (proc, key = lambda x:x[2]) proc = sorted (proc) # Calling function findgc for # finding Gantt Chart findgc()# This code is contributed by# Shubham Singh(SHUBHAMSINGH10) |
C#
// C# implementation for Priority Scheduling with// Different Arrival Time priority scheduling// 1. sort the processes according to arrival time// 2. if arrival time is same the acc to priority// 3. apply fcfsusing System;class Program{ static int totalprocess = 5; static int[][] proc = new int[totalprocess][]; static int[] arrivaltime = new int[] {1, 2, 3, 4, 5}; static int[] bursttime = new int[] {3, 5, 1, 7, 4}; static int[] priority = new int[] {3, 4, 1, 7, 8}; // Driver code static void Main(string[] args) { for (int i = 0; i < totalprocess; i++) { proc[i] = new int[4]; proc[i][0] = arrivaltime[i]; proc[i][1] = bursttime[i]; proc[i][2] = priority[i]; proc[i][3] = i + 1; } Array.Sort(proc, (x, y) => x[2].CompareTo(y[2])); Array.Sort(proc, (x, y) => x[0].CompareTo(y[0])); Findgc(); } // Using FCFS Algorithm to find Waiting time static void GetWtTime(int[] wt) { // declaring service array that stores // cumulative burst time int[] service = new int[totalprocess]; // Initialising initial elements // of the arrays service[0] = 0; wt[0] = 0; for (int i = 1; i < totalprocess; i++) { service[i] = proc[i - 1][1] + service[i - 1]; wt[i] = service[i] - proc[i][0] + 1; // If waiting time is negative, // change it o zero if (wt[i] < 0) { wt[i] = 0; } } } // Filling turnaroundtime array static void GetTatTime(int[] tat, int[] wt) { for (int i = 0; i < totalprocess; i++) { tat[i] = proc[i][1] + wt[i]; } } static void Findgc() { // Declare waiting time and // turnaround time array int[] wt = new int[totalprocess]; int[] tat = new int[totalprocess]; int wavg = 0; int tavg = 0; // Function call to find waiting time array GetWtTime(wt); // Function call to find turnaround time GetTatTime(tat, wt); int[] stime = new int[totalprocess]; int[] ctime = new int[totalprocess]; stime[0] = 1; ctime[0] = stime[0] + tat[0]; Console.WriteLine("Process_no\tStart_time\tComplete_time\tTurn_Around_Time\tWaiting_Time"); // calculating starting and ending time for (int i = 0; i < totalprocess; i++) { wavg += wt[i]; tavg += tat[i]; Console.WriteLine(proc[i][3] + "\t\t" + stime[i] + "\t\t" + ctime[i] + "\t\t" + tat[i] + "\t\t\t" + wt[i]); // display the process details if (i != totalprocess - 1) { stime[i + 1] = ctime[i]; ctime[i + 1] = stime[i + 1] + tat[i + 1] - wt[i + 1]; } } // display the average waiting time // and average turn around time Console.WriteLine("Average waiting time is: " + (double)wavg / totalprocess); Console.WriteLine("Average turnaround time is: " + (double)tavg / totalprocess); }}// This code is contributed by shiv1o43g |
Javascript
var totalprocess = 5;var proc = [];for (var i = 0; i < 5; i++) { var l = []; for (var j = 0; j < 4; j++) { l.push(0); } proc.push(l);}function get_wt_time(wt) { var service = new Array(5).fill(0); service[0] = 0; wt[0] = 0; for (var i = 1; i < totalprocess; i++) { service[i] = proc[i - 1][1] + service[i - 1]; wt[i] = service[i] - proc[i][0] + 1; if (wt[i] < 0) { wt[i] = 0; } }}function get_tat_time(tat, wt) { for (var i = 0; i < totalprocess; i++) { tat[i] = proc[i][1] + wt[i]; }}function findgc() { var wt = new Array(5).fill(0); var tat = new Array(5).fill(0); var wavg = 0; var tavg = 0; get_wt_time(wt); get_tat_time(tat, wt); var stime = new Array(5).fill(0); var ctime = new Array(5).fill(0); stime[0] = 1; ctime[0] = stime[0] + tat[0]; for (var i = 1; i < totalprocess; i++) { stime[i] = ctime[i - 1]; ctime[i] = stime[i] + tat[i] - wt[i]; } console.log("Process_no\tStart_time\tComplete_time\tTurn_Around_Time\tWaiting_Time" ); for (var i = 0; i < totalprocess; i++) { wavg += wt[i]; tavg += tat[i]; console.log( proc[i][3] + "\t\t" + stime[i] + "\t\t" + ctime[i] + "\t\t" + tat[i] + "\t\t\t" + wt[i] ); } console.log("Average waiting time is : " + wavg / totalprocess); console.log("average turnaround time : " + tavg / totalprocess);}var arrivaltime = [1, 2, 3, 4, 5];var bursttime = [3, 5, 1, 7, 4];var priority = [3, 4, 1, 7, 8];for (var i = 0; i < totalprocess; i++) { proc[i][0] = arrivaltime[i]; proc[i][1] = bursttime[i]; proc[i][2] = priority[i]; proc[i][3] = i + 1;}proc.sort(function (a, b) { if (a[2] == b[2]) { return a[0] - b[0]; } else { return a[2] - b[2]; }});findgc();// This code is contributed by shiv1o43g |
Output:
Process_no Start_time Complete_time Turn_Around_Time Waiting_Time 1 1 4 3 0 2 5 10 8 3 3 4 5 2 1 4 10 17 13 6 5 17 21 16 12 Average Waiting Time is : 4.4 Average Turn Around time is : 8.4
Time Complexity: O(N * logN), where N is the total number of processes.
Auxiliary Space: O(N)
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