Question

Hi Guys,

The assignment in Process Scheduling Operating System to write C code that implement FCFS & Round-Robin ( Without using any array) but we can use linkedlist

Answer 1

PROGRAM FOR FCFS(first come first serve)PROCESS SCHEDULING

#include <stdio.h>
#include <stdlib.h>
/*we know that fcfs is non preemptive scheduling algorithm that means we cannot preempt the process in middle
        the process will be executed till its end */
struct fcfs
{
   int at,ct,bt,tat,pid,wt;
};// making a structure
int main()
{
   int n,i,j;
   float awt,atat;
    struct fcfs allfcfs[100],temp; //decrearing a structure
    printf("enter how many processes u want to enter:");
    scanf("%d",&n);// entering no of processes you want to execute
    for(i=0;i<n;i++)
    {
       printf("enter the arrival time of %d process:",i+1);
       scanf("%d",&allfcfs[i].at);// enter arrival time of process i
       printf("enter the burst time of %d process:",i+1);
       scanf("%d",&allfcfs[i].bt);// enter burst time of process i
       allfcfs[i].pid=i+1;
   }// this loop is all about entering process details
   for(i=0;i<n;i++)
   {
       for(j=0;j<n-1;j++)
       {
           if(allfcfs[j].at>allfcfs[j+1].at)
           {
               temp=allfcfs[j];
               allfcfs[j]=allfcfs[j+1];
               allfcfs[j+1]=temp;
           }
       }
      
   }// this loop is all about sorting process based on their arrival time
   int c=0;
   for(i=0;i<n;i++)
   {
       if(i==0)
       {
            c=allfcfs[i].at;  
       }
       else
       {
           if(allfcfs[i].at>allfcfs[i-1].ct)
           {
               c=allfcfs[i].at-allfcfs[i-1].ct;
           }
           else
           {
               c=0;
           }
        }
        if(i>0)
       {
           allfcfs[i].ct=allfcfs[i-1].ct+allfcfs[i].bt+c;   calculating cpu time of process i
       }  
       else
       {  
           allfcfs[i].ct=allfcfs[i].bt+c;
       }
       allfcfs[i].tat=allfcfs[i].ct-allfcfs[i].at;// calculting turn around time of process i
       allfcfs[i].wt=allfcfs[i].ct-allfcfs[i].bt-allfcfs[i].at; calculating waiting time of process i  
       awt=awt+allfcfs[i].wt;// for calculating average waiting time we are finding the sum of waiting times of all processes
       atat=atat+allfcfs[i].tat;
   }
   printf("Average Turn Around Time is %f\n",(float)(atat/n));//printing average turn around time
    printf("Average Waiting time is %f",(float)(awt/n));// printing average waiting time
}

PROGRAM FOR RR(round robin) PROCESS SCHEDULING

#include<stdio.h>
struct RR{
    int pid,bt,bt1,ct,tat,wt,f;
};     // making a structure for rr

main()
{
   struct RR rr[100];declearing a structure
    int n,i,q,st=0,c=0;
    float atat=0,awt=0;
    printf("enter no of processes:");//entering how many processes you want to enter
    scanf("%d",&n);
    for (i=0;i<n;i++){
        rr[i].pid=i+1;
        rr[i].f=0;
        printf("enter the bt:");
        scanf("%d",&rr[i].bt);
        rr[i].bt1=rr[i].bt;
        printf("---------------------------\n");
    }   // entering the process details
  
    printf("enter time quantum:");
  
    scanf("%d",&q);// entering the time quantum(the amount time will be given to every process while execution)
  
    while (1)
   {
      
     for (i=0;i<n;i++)
   {
        if ((rr[i].bt<=q)&&(rr[i].f==0))/*checking whether the process is completed or not and also checking whether the             remaining burst time of process is less than quantum or not*/
       {
            st=st+rr[i].bt;//here we are changing the cpu time by executing that process i
            rr[i].bt=0;// we are changing the burst time to 0 because the process is completed
            rr[i].f=1;// changing flag value to 1 because process i is completed
            c++;   // I used this variable to check no of processes completed till now
            rr[i].ct=st;
            rr[i].tat=rr[i].ct;// changing turn around time
            atat=atat+rr[i].tat; // changing average turn around time
            rr[i].wt=rr[i].tat-rr[i].bt1;waiting time calculation
            awt=awt+rr[i].wt;// changing average waiting time
        }
        else if (rr[i].bt>q) // checking burst time is greater than quantum if true we simply add that quantum to cpu time
       {
            st=st+q;
            rr[i].bt=rr[i].bt-q; //we decrement quantum value from the burst time because processi is executed q amount of time
        }
     }
     if (c==n)
        break;// break if all processes are completly executed
    }
    // printing average turn around time and waiting time
    printf("average Turn Around Time is %f\n",(float)(atat/n));// printing average turn around time
    printf("average Waiting Time is %f",(float)(awt/n));// printing average waiting time
}