Os lab 1st mid

OS LAB MANUAL

MURALI

OS Lab Manual

Operating Systems

K.MURALI

COMPUTER SCIENCE AND ENGINEERING

GUDLAVALLERU ENGINEERING COLLEGE

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OS LAB MANUAL

MURALI

1) Simulate the following CPU scheduling algorithms
a) FCFS
b) SJF
c) Priority
d) Round Robin

a) FCFS:
AIM : A program to simulate the FCFS CPU scheduling algorithm

PROGRAM:

#include<stdio.h>
#include<string.h>
#include<conio.h>
main()
{
char pn[10][10],t[10];
int arr[10],bur[10],star[10],finish[10],tat[10],wt[10],i,j,n,temp;
int totwt=0,tottat=0;
//clrscr();
printf("Enter the number of processes:");
scanf("%d",&n);
for(i=0;i<n;i++)
{
printf("Enter the Process Name, Arrival Time & Burst Time:");
scanf("%s%d%d",&pn[i],&arr[i],&bur[i]);
}
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
{
if(arr[i]<arr[j])
{
temp=arr[i];
arr[i]=arr[j];
arr[j]=temp;
temp=bur[i];
bur[i]=bur[j];
bur[j]=temp;
strcpy(t,pn[i]);
strcpy(pn[i],pn[j]);
strcpy(pn[j],t);
}
}

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}
for(i=0;i<n;i++)
{
if(i==0)
star[i]=arr[i];
else
star[i]=finish[i-1];
wt[i]=star[i]-arr[i];
finish[i]=star[i]+bur[i];
tat[i]=finish[i]-arr[i];
}
printf("nPName Arrtime Burtime WaitTime Start TAT Finish");
for(i=0;i<n;i++)
{
printf("n%st%3dt%3dt%3dt%3dt%6dt%6d",pn[i],arr[i],bur[i],wt[i],star[i],tat[i],finis
h[i]);
totwt+=wt[i];
tottat+=tat[i];
}
printf("nAverage Waiting time:%f",(float)totwt/n);
printf("nAverage Turn Around Time:%f",(float)tottat/n);
getch();
return 0;
}
OUTPUT:

Input:

Enter the number of processes: 3
Enter the Process Name, Arrival Time & Burst Time: p1 2 4

Output:

PName Arrtime Burtime WaitTime Srart TAT Finish
p3 1 6 0 1 6 7
p1 2 4 5 7 9 11
p2 3 5 8 11 13 16

Average Waiting Time: 4.3333333
Average Turn Around Time: 9.33333333

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b) SJF:
AIM: A program to simulate the SJF CPU scheduling algorithm

PROGRAM:

#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
int et[20],at[10],n,i,j,temp,st[10],ft[10],wt[10],ta[10];
int totwt=0,totta=0;
float awt,ata;
char pn[10][10],t[10];
clrscr();
printf("Enter the number of process:");
scanf("%d",&n);
for(i=0;i<n;i++)
{
printf("Enter process name, arrival time & execution time:");
flushall();
scanf("%s%d%d",pn[i],&at[i],&et[i]);
}
for(i=0;i<n;i++)
for(j=0;j<n;j++)
{
if(et[i]<et[j])
{
temp=at[i];
at[i]=at[j];
at[j]=temp;
temp=et[i];
et[i]=et[j];
et[j]=temp;
strcpy(t,pn[i]);
strcpy(pn[j],t);
}
}
for(i=0;i<n;i++)
{
if(i==0)
st[i]=at[i];
else
st[i]=ft[i-1];

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wt[i]=st[i]-at[i];
ft[i]=st[i]+et[i];
ta[i]=ft[i]-at[i];
totwt+=wt[i];
totta+=ta[i];
}
awt=(float)totwt/n;
ata=(float)totta/n;
printf("nPnametarrivaltimetexecutiontimetwaitingtimettatime");
for(i=0;i<n;i++)
printf("n%st%5dtt%5dtt%5dtt%5d",pn[i],at[i],et[i],wt[i],ta[i]);
printf("nAverage waiting time is:%f",awt);
printf("nAverage turnaroundtime is:%f",ata);
getch();
}

OUTPUT:

Input:

Enter the Process Name, Arrival Time & Burst Time: 1 4 6

Output:

Pname arrivaltime executiontime waitingtime tatime
1 4 6 0 6
3 6 11 4 15
2 5 15 16 31


7

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c) Priority:

AIM: A program to simulate the priority CPU scheduling algorithm

PROGRAM:

#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
int et[20],at[10],n,i,j,temp,p[10],st[10],ft[10],wt[10],ta[10];
int totwt=0,totta=0;
float awt,ata;
char pn[10][10],t[10];
clrscr();
printf("Enter the number of process:");
scanf("%d",&n);
for(i=0;i<n;i++)
{
printf("Enter process name,arrivaltime,execution time & priority:");
flushall();
scanf("%s%d%d%d",pn[i],&at[i],&et[i],&p[i]);
}
for(i=0;i<n;i++)
for(j=0;j<n;j++)
{
if(p[i]<p[j])
{
temp=p[i];
p[i]=p[j];
p[j]=temp;
temp=at[i];
at[i]=at[j];
at[j]=temp;
temp=et[i];
et[i]=et[j];
et[j]=temp;
strcpy(t,pn[i]);
strcpy(pn[j],t);
}
}
for(i=0;i<n;i++)
{

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if(i==0)
{
st[i]=at[i];
wt[i]=st[i]-at[i];
ft[i]=st[i]+et[i];
ta[i]=ft[i]-at[i];
}
else
{
st[i]=ft[i-1];
wt[i]=st[i]-at[i];
ft[i]=st[i]+et[i];
ta[i]=ft[i]-at[i];
}
totwt+=wt[i];
totta+=ta[i];
}
awt=(float)totwt/n;
ata=(float)totta/n;
printf("nPnametarrivaltimetexecutiontimetprioritytwaitingtimettatime");
for(i=0;i<n;i++)
printf("n%st%5dtt%5dtt%5dtt%5dtt%5d",pn[i],at[i],et[i],p[i],wt[i],ta[i]);
printf("nAverage waiting time is:%f",awt);
printf("nAverage turnaroundtime is:%f",ata);
getch();
}

OUTPUT:
Input:

Enter the Process Name, Arrival Time, execution time & priority: 1 2 3 1

Output:

Pname arrivaltime executiontime priority waitingtime tatime
1 2 3 1 0 3
2 4 5 2 1 6
3 5 6 3 5 11


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d) Round Robin:
AIM: A program to simulate the Round Robin CPU scheduling algorithm

PROGRAM:

#include<stdio.h>
#include<conio.h>
void main()
{
int et[30],ts,n,i,x=0,tot=0;
char pn[10][10];
clrscr();
printf("Enter the no of processes:");
scanf("%d",&n);
printf("Enter the time quantum:");
scanf("%d",&ts);
for(i=0;i<n;i++)
{
printf("enter process name & estimated time:");
scanf("%s %d",pn[i],&et[i]);
}
printf("The processes are:");
for(i=0;i<n;i++)
printf("process %d: %sn",i+1,pn[i]);
for(i=0;i<n;i++)
tot=tot+et[i];
while(x!=tot)
{
for(i=0;i<n;i++)
{
if(et[i]>ts)
{
x=x+ts;
printf("n %s -> %d",pn[i],ts);

et[i]=et[i]-ts;
}

else
if((et[i]<=ts)&&et[i]!=0)
{
x=x+et[i];
printf("n %s -> %d",pn[i],et[i]);
et[i]=0;}
}

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}
printf("n Total Estimated Time:%d",x);
getch();
}
OUTPUT:

Input:

Enter the no of processes: 2
Enter the time quantum: 3

Enter the process name & estimated time: p1 12
Enter the process name & estimated time: p2 15

Output:
p1 -> 3
p2 -> 3
p1 -> 3
p2 -> 3
p1 -> 3
p2 -> 3
p1 -> 3
p2 -> 3
p2 -> 3

Total Estimated Time: 27

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2) Simulate the MVT and MFT.

MVT:
AIM: A program to simulate the MVT.

PROGRAM:

#include<stdio.h>
#include<conio.h>
void main()
{
int m=0,m1=0,m2=0,p,count=0,i;
clrscr();
printf("enter the memory capacity:");
scanf("%d",&m);
printf("enter the no of processes:");
scanf("%d",&p);
for(i=0;i<p;i++)
{
printf("nenter memory req for process%d: ",i+1);
scanf("%d",&m1);
count=count+m1;
if(m1<=m)
{
if(count==m)
printf("there is no further memory remaining:");
printf("the memory allocated for process%d is: %d ",i+1,m);
m2=m-m1;
printf("nremaining memory is: %d",m2);
m=m2;
}
}
else
{
printf("memory is not allocated for process%d",i+1);
}
printf("nexternal fragmentation for this process is:%d",m2);
}
getch();

}

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OUTPUT:

Input:

Enter the memory capacity: 80
Enter no of processes: 2
Enter memory req for process1: 23

Output:

The memory allocated for process1 is: 80
Remaining memory is: 57
External fragmentation for this process is: 57
Enter memory req for process2: 52
The memory allocated for process2 is: 57
Remaining memory is: 5
External fragmentation for this process is: 5

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MFT:
AIM: A Program to simulate the MFT

PROGRAM:

#include<stdio.h>
#include<conio.h>
int main()
{
int m,p,s,p1;
int m1[4],i,f,f1=0,f2=0,fra1,fra2,s1,pos;
clrscr();
printf("Enter the memory size:");
scanf("%d",&m);
printf("Enter the no of partitions:");
scanf("%d",&p);
s=m/p;
printf("Each partn size is:%d",s);
printf("nEnter the no of processes:");
scanf("%d",&p1);
pos=m;
for(i=0;i<p1;i++)
{
if(pos<s)
{
printf("nThere is no further memory for process%d",i+1);
m1[i]=0;
break;
}
else
{
printf("nEnter the memory req for process%d:",i+1);
scanf("%d",&m1[i]);
if(m1[i]<=s)
{
printf("nProcess is alloca ted in partition%d",i+1);
fra1=s-m1[i];
printf("nInternal fragmentation for process is:%d",fra1);
f1=f1+fra1;
pos=pos-s;

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}
else
{
printf("nProcess not allocated in partition%d",i+1);
s1=m1[i];
while(s1>s)
{
s1=s1-s;
pos=pos-s;
}
pos=pos-s;
fra2=s-s1;
f2=f2+fra2;
printf("nExternal Fragmentation for this process is:%d",fra2);
}
}
}
printf("nProcesstallocatedmemory");
for(i=0;i<p1;i++)
printf("n%5dt%5d",i+1,m1[i]);
f=f1+f2;
printf("nThe tot no of fragmentation is:%d",f);
getch();
return 0;
}

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OUTPUT:

Input:

Enter the memory size: 80
Enter the no of partitions: 4
Each partition size: 20
Enter the memory req for process1: 18

Output:

Process1 is allocated in partn1
Internal fragmentation for process1 is: 2
Enter the memory req for process2: 22
Process2 is not allocated in partn2
External fragmentation for process2 is: 18

Process memory allocated
1 20 18
2 20 22

The tot no of fragmentation is: 20

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3) Simulate all Page Replacement Algorithms
a) FIFO
b) LRU

a) FIFO:
AIM: A program to simulate FIFO Page Replacement Algorithm

PROGRAM:

#include<stdio.h>
#include<conio.h>
void main()
{
int a[5],b[20],n,p=0,q=0,m=0,h,k,i,q1=1;
char f='F';
clrscr();
printf("Enter the Number of Pages:");
scanf("%d",&n);
printf("Enter %d Page Numbers:",n);
for(i=0;i<n;i++)
scanf("%d",&b[i]);
for(i=0;i<n;i++)
{if(p==0)
{
if(q>=3)
q=0;
a[q]=b[i];
q++;
if(q1<3)
{
q1=q;
}
}
printf("n%d",b[i]);
printf("t");
for(h=0;h<q1;h++)
printf("%d",a[h]);
if((p==0)&&(q<=3))
{
printf("-->%c",f);
m++;
}
p=0;
for(k=0;k<q1;k++)

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{
if(b[i+1]==a[k])
p=1;
}
}
printf("nNo of faults:%d",m);
getch();
}
OUTPUT:

Input:

Enter the Number of Pages: 12
Enter 12 Page Numbers:
232152453252

Output:

2 2-> F
3 23-> F
2 23
1 231-> F
5 531-> F
2 521-> F
4 524-> F
5 524
3 324-> F
2 324
5 354-> F
2 352-> F

No of faults: 9

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b) LRU:
AIM: A program to simulate LRU Page Replacement Algorithm

PROGRAM:

#include<stdio.h>
#include<conio.h>
void main()
{
int g=0,a[5],b[20],p=0,q=0,m=0,h,k,i,q1=1,j,u,n;
char f='F';
clrscr();
printf("Enter the number of pages:");
scanf("%d",&n);
printf("Enter %d Page Numbers:",n);
for(i=0;i<n;i++)
scanf("%d",&b[i]);
for(i=0;i<n;i++)
{if(p==0)
{
if(q>=3)
q=0;
a[q]=b[i];
q++;
if(q1<3)
{
q1=q;
//g=1;
}
}
printf("n%d",b[i]);
printf("t");
for(h=0;h<q1;h++)
printf("%d",a[h]);
if((p==0)&&(q<=3))
{
printf("-->%c",f);
m++;
}
p=0;
g=0;
if(q1==3)
{
for(k=0;k<q1;k++)
{

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if(b[i+1]==a[k])
p=1;
}
for(j=0;j<q1;j++)
{
u=0;
k=i;
while(k>=(i-1)&&(k>=0))
{
if(b[k]==a[j])
u++;
k--;
}
if(u==0)
q=j;
}
}
else
{
for(k=0;k<q;k++)
{
if(b[i+1]==a[k])
p=1;
}
}
}
printf("nNo of faults:%d",m);
getch();
}

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OUTPUT:

Input:

Enter the Number of Pages: 12
Enter 12 Page Numbers:
232152453252

Output:

2 2-> F
3 23-> F
2 23
1 231-> F
5 251-> F
2 251
4 254-> F
5 254
3 354-> F
2 352-> F
5 352
2 352

No of faults: 7

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4) Simulate Paging technique of Memory Management.

AIM: A program to simulate Paging technique of memory management.

PROGRAM:

#include<stdio.h>
#include<conio.h>
main()
{
int np,ps,i;
int *sa;
clrscr();
printf("enter how many pagesn");
scanf("%d",&np);
printf("enter the page size n");
scanf("%d",&ps);
sa=(int*)malloc(2*np);
for(i=0;i<np;i++)
{
sa[i]=(int)malloc(ps);
printf("page%dt address %un",i+1,sa[i]);
}
getch();
}

OUTPUT:

Input:

Enter how many pages: 5
Enter the page size: 4

Output:

Page1 Address: 1894
Page2 Address: 1902
Page3 Address: 1910
Page4 Address: 1918
Page5 Address: 1926

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