Solve FCFS( NON - PREMPTIVE ) for the following process and calculate : Please s

Question

Solve FCFS(NON - PREMPTIVE) for the following process and calculate :

Please show work so I can understand this., Can you also mention how we take into account i/o time.

U (CPU utilization),

WT (waiting times)

TT (turnaround times),

RT(response times)

AVG WT (avg waiting times)

AVG TT (avg turnaround times),

AVG RT(avg response times)

Process Data:

process goes {CPU burst, I/O time, CPU burst, I/O time, CPU burst, I/O time,…….., last CPU burst}

P1 {4,24,5,73,3,31,5,27,4,33,6,43,4,64,5,19,2}

P2 {18,31,19,35,11,42,18,43,19,47,18,43,17,51,19,32,10}

P3 {6,18,4,21,7,19,4,16,5,29,7,21,8,22,6,24,5}

P4 {17,42,19,55,20,54,17,52,15,67,12,72,15,66,14}

P5 {5,81,4,82,5,71,3,61,5,62,4,51,3,77,4,61,3,42,5}

P6 {10,35,12,41,14,33,11,32,15,41,13,29,11}

P7 {21,51,23,53,24,61,22,31,21,43,20}

P8 {11,52,14,42,15,31,17,21,16,43,12,31,13,32,15}

Explanation / Answer

Kindly use the below C++ program to calculate the required timings:

#include<iostream>

using namespace std;

int main()
{
int n,bursttime[20],waitingtime[20],turnaroundtime[20],avwaitingtime=0,avturnaroundtime=0,i,j;
cout<<"Enter total number of processes:";
cin>>n;

cout<<" Enter Process Burst Time ";
for(i=0;i<n;i++)
{
cout<<"P["<<i+1<<"]:";
cin>>bursttime[i];
}

waitingtime[0]=0; //waiting time for first process is 0 in our case

//calculating waiting time
for(i=1;i<n;i++)
{
waitingtime[i]=0;
for(j=0;j<i;j++)
waitingtime[i]+=bursttime[j];
}

cout<<" Process Burst Time Waiting Time Turnaround Time";

//calculating turnaround time
for(i=0;i<n;i++)
{
turnaroundtime[i]=bursttime[i]+waitingtime[i];
avwaitingtime+=waitingtime[i];
avturnaroundtime+=turnaroundtime[i];
cout<<" P["<<i+1<<"]"<<" "<<bursttime[i]<<" "<<waitingtime[i]<<" "<<turnaroundtime[i];
}

avwaitingtime/=i;
avturnaroundtime/=i;
cout<<" Average Waiting Time:"<<avwaitingtime;
cout<<" Average Turnaround Time:"<<avturnaroundtime;

return 0;
}

The results are as below:

Avg Wait time (WT) - 285.875

Avg Turnaround time (TT) - 691.5

Avg Response time (RT) - 36.25

CPU utilization - 82.02%

CPU utilization is maximized by running long-running CPU-bound tasks without performing context switches. I/O device utilization is maximized by scheduling I/O-bound jobs as soon as they become ready to run, thereby incurring the overheads of context switches.

Hope this helps :)

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