Question

This is a C program question

you will implement a program to show the performance of FCFS scheduling algorithm with I/O burst. Your program should get a file (e.g., “jobs.txt”) as the command-line input, and read the contents of the file. This file contains a set of processes.

For example, consider the file with the following content:

1:(45,15);(16,20);(80,10);(40,-1)

2:(15,10);(60,15);(90,10);(85,20);(20,-1)

3:(30,15);(40,20);(5,15);(10,15);(15,-1)

In this example we have 3 processes, each process is represented in a separate line. The general format of a line is as follows:

<process-id>:(< cpu-burst1, io-burst1>);(< cpu-burst2, io-burst2>);...(< cpu-bursti, io-bursti>)

The first token is the unique process id. After process-id you have a colon (:) delimiter. Then you will see a list of tuples separated by semicolons (;).

Each tuple in parentheses indicates the next cpu-burst and io-burst lengths of the process.

The cpu and io burst length in terms of milliseconds. If the last io-burst is -1, then it means that the process terminates without making an I/O.

 Note that this input is just an example, I may use a different input file having a different content for testing your codes, but the format of the file will be same. ( Be careful on duplicate last line issue when reading from the input file)

 You will assume that ;

o all the jobs arrive at the same time (t=0), the order of arrival is the same as the order of process-ids (i.e., smaller ids arrive earlier).

o the process never waits at the device queues and I/O starts immediately

First Come First Served (FCFS) Algorithm

Implement FCFS scheduling policy. You should print the following

a. Average turnaround time: The average of the turnaround times of all process

b. Average waiting time: The average of the total waiting time for all processes.

Thanks in advance!

Answer 1

Answer:

First Come First Serve (FCFS) CPU scheduling program:

Note : Run this code in any online compiler to get best output without any unwanted error

Code:

#include<stdio.h>
// Function to find the waiting time for all processes
void findWaitingTime(int processes[], int n,
                          int bt[], int wt[])
{
    // waiting time for first process is 0
    wt[0] = 0;
  
    // calculating waiting time
    for (int i = 1; i < n ; i++ )
        wt[i] = bt[i-1] + wt[i-1] ;
}
  
// 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 wt[n], tat[n], total_wt = 0, total_tat = 0;
  
    //Function to find waiting time of all processes
    findWaitingTime(processes, n, bt, wt);
  
    //Function to find turn around time for all processes
    findTurnAroundTime(processes, n, bt, wt, tat);
  
    //Display processes along with all details
    printf("Processes   Burst time   Waiting time   Turn around time\n");
  
    // Calculate total waiting time and total turnaround time
    for (int i=0; i<n; i++)
    {
        total_wt = total_wt + wt[i];
        total_tat = total_tat + tat[i];
        printf("   %d ",(i+1));
        printf("       %d ", bt[i] );
        printf("       %d",wt[i] );
        printf("       %d\n",tat[i] );
    }
    int s=(float)total_wt / (float)n;
    int t=(float)total_tat / (float)n;
    printf("Average waiting time = %d",s);
    printf("\n");
    printf("Average turn around time = %d ",t);
}
  
// 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};
  
    findavgTime(processes, n, burst_time);
    return 0;
}

Output:

Processes Burst time Waiting time Turn around time 10 15 23 15 Average waiting time = 8 Average turn around time = 16 ... Program finished with exit code o Press ENTER to exit console. I