Menu-Driven program for cpu scheduling
On-campus and online computer science courses to Learn the basic concepts of Computer Science.This tutorial will cover c ,c++, java, data structure and algorithm,computer graphics,microprocessor,analysis of algorithms,Digital Logic Design and Analysis,computer architecture,computer networks,operating system.
code in Java:import java.io.*;
public class MenuCPU {
public static void main(String args[]) throws IOException
{
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int n;
int choice = 0;
int q = 0;
System.out.println("Please enter the number of Processes: ");
n = Integer.parseInt(br.readLine());
System.out.println("Please choose the Algorithm to be applied:\n\t1. FCFS\n\t2. SRTF\n\t3. Round Robin");
choice = Integer.parseInt(br.readLine());
if(choice == 3)//We need Time Quantum only if Round Robin is chosen
{
System.out.println("Please enter the Time Quantum: ");
q = Integer.parseInt(br.readLine());
}
int proc[][] = new int[n + 1][4];
//proc[][0] is the AT array
//proc[][1] is the BT array
//proc[][2] is the WT array
//proc[][3] is the TT array
for(int i = 1; i <= n; i++)
{
if(choice == 2)//We need AT only for SRTF
{
System.out.println("Please enter the Arrival Time for Process " + i + ": ");
proc[i][0] = Integer.parseInt(br.readLine());
}
else
proc[i][0] = 0;
System.out.println("Please enter the Burst Time for Process " + i + ": ");
proc[i][1] = Integer.parseInt(br.readLine());
}
System.out.println();
//Calculation of Total Time and Initialization of Time Chart array
int total_time = 0;
for(int i = 1; i <= n; i++)
{
total_time += proc[i][1];
}
int time_chart[] = new int[total_time];
int sel_proc = 1;
int current_q = 0;
for(int i = 0; i < total_time; i++)
{
//Used only in SRTF
if(choice == 2)
{
//Selection of shortest process which has arrived
sel_proc = 0;
int min = 99999;
for(int j = 1; j <= n; j++)
{
if(proc[j][0] <= i)//Condition to check if Process has arrived
{
if(proc[j][1] < min && proc[j][1] != 0)
{
min = proc[j][1];
sel_proc = j;
}
}
}
}
//Assign selected process to current time in the Chart
time_chart[i] = sel_proc;
//Decrement Remaining Time of selected process by 1 since it has been assigned the CPU for 1 unit of time
proc[sel_proc][1]--;
//WT and TT Calculation
for(int j = 1; j <= n; j++)
{
if(proc[j][0] <= i)
{
if(proc[j][1] != 0)
{
proc[j][3]++;//If process has arrived and it has not already completed execution its TT is incremented by 1
if(j != sel_proc)//If the process has not been currently assigned the CPU and has arrived its WT is incremented by 1
proc[j][2]++;
}
else if(j == sel_proc)//This is a special case in which the process has been assigned CPU and has completed its execution
proc[j][3]++;
}
}
//Printing the Time Chart
if(i != 0)
{
if(sel_proc != time_chart[i - 1])
//If the CPU has been assigned to a different Process we need to print the current value of time and the name of
//the new Process
{
System.out.print("--" + i + "--P" + sel_proc);
}
}
else//If the current time is 0 i.e the printing has just started we need to print the name of the First selected Process
System.out.print(i + "--P" + sel_proc);
if(i == total_time - 1)//All the process names have been printed now we have to print the time at which execution ends
System.out.print("--" + (i + 1));
//Used only in Round Robin
if(choice == 3)
{
//Updating value of sel_proc for next iteration
current_q++;
if(current_q == q || proc[sel_proc][1] == 0)//If Time slice has expired or the current process has completed execution
{
current_q = 0;
//This will select the next valid value for sel_proc
for(int j = 1; j <= n; j++)
{
sel_proc++;
if(sel_proc == (n + 1))
sel_proc = 1;
if(proc[sel_proc][1] != 0)
break;
}
}
}
//Used only in FCFS
if(choice == 1)
{
//If current process has been completed we select the next process from the list
if(proc[sel_proc][1] == 0)
sel_proc++;
}
}
System.out.println();
System.out.println();
//Printing the WT and TT for each Process
System.out.println("P\t WT \t TT ");
for(int i = 1; i <= n; i++)
{
System.out.printf("%d\t%3dms\t%3dms",i,proc[i][2],proc[i][3]);
System.out.println();
}
System.out.println();
//Printing the average WT & TT
float WT = 0,TT = 0;
for(int i = 1; i <= n; i++)
{
WT += proc[i][2];
TT += proc[i][3];
}
WT /= n;
TT /= n;
System.out.println("The Average WT is: " + WT + "ms");
System.out.println("The Average TT is: " + TT + "ms");
}
}
output:-Please enter the number of Processes: 5 Please choose the Algorithm to be applied: 1. FCFS 2. SRTF 3. Round Robin 2 Please enter the Arrival Time for Process 1: 0 Please enter the Burst Time for Process 1: 8 Please enter the Arrival Time for Process 2: 1 Please enter the Burst Time for Process 2: 4 Please enter the Arrival Time for Process 3: 2 Please enter the Burst Time for Process 3: 9 Please enter the Arrival Time for Process 4: 3 Please enter the Burst Time for Process 4: 5 Please enter the Arrival Time for Process 5: 3 Please enter the Burst Time for Process 5: 9 0--P1--1--P2--5--P4--10--P1--17--P3--26--P5--35 P WT TT 1 9ms 17ms 2 0ms 4ms 3 15ms 24ms 4 2ms 7ms 5 23ms 32ms The Average WT is: 9.8ms The Average TT is: 16.8ms --------------------------------
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