EX:NO: 1 WRITE PROGRAMS USING THE FOLLOWING SYSTEM CALLS OF UNIX OPERATING SYSTEM:
Fork, exec, getpid, exit, wait, close, stat, opendir, readdir. FORK & GETPID
Aim :
To Create a process in the following hierarchy Parent Child1 Child2 Child3 Algorithm
1. Declare the necessary variables.
2. Parent process is the process of the program which is running. 3. Create the child1 process using fork() When parent is active. 4. Create the child2 process using fork() when child1 is active. 5. Create the child3 process using fork() when child2 is active. Program //process1.c #include<stdio.h> void main() { int pid1,pid2,pid3;
printf("Parent id is %d and root id is %d\n",getpid(),getppid()); pid1=fork();
if(pid1==0) {
printf("Process 1 id is %d and its parent id is %d\n",getpid(),getppid()); pid2=fork();
}
if(pid2==0) {
printf("Process 2 id is %d and its parent id is %d\n",getpid(),getppid()); pid3=fork();
}
{
printf("Process 3 id is %d and its parent id is %d\n",getpid(),getppid()); }
}
Sample Output $ cc process1.c $ a.out
Parent id is 3553 and root id is 2495
Process 1 id is 3554 and its parent id is 3553 Process 2 id is 3555 and its parent id is 3554 Process 3 id is 3556 and its parent id is 3555 EXECl
Aim
To Execute a Unix Command (Who) in a ‘C’ program using execl() system call. Problem Description
The Unix system call transfers an executable binary files into a process that are the exec family of sytem calls.
General Format
Execl(filename,arg0,arg1,………argn,0) Char *filename *
Arg0* , arg1* ,…….argn*
Where filenames are the executable binary files to be transferred into a process. arg0 through argn define the argument to be passed to the process.
Program //program1.c #include<stdio.h> #include<sys/types.h> #include<unistd.h> void main() { int pid1; pid1=fork(); if(pid1==0) { printf("Process id is %d ",getpid()); printf("and its parent id is %d”,getppid()); execl("/bin/who","who",0); } } Sample Output $ cc program2.c $ a.out
Process id is 3553 and parent id is 2495 Root ttyp2 jun25 03.30
sit ttyp1 jun25 03.30 OPENDIR & READDIR
Aim:
To write a C program to display the files in the given directory Algorithm:
1. Start the program
2. Declare the variable to the structure dirent (defines the file system-independent directory) and also for DIR
3. Specify the directory path to be displayed using the opendir system call
4. Check for the existence of the directory and read the contents of the directory using readdir system call (returns a pointer to the next active directory entry)
5. Repeat the above step until all the files in the directory are listed 6. Stop the program
Program #include<stdio.h> #include<dirent.h> main() { DIR *p; struct dirent *dp; p=opendir("."); //p=opendir("./shantha"); if(p==NULL) { perror("opendir"); exit(0); } dp=readdir(p); while(p!=NULL) { printf("%d%s\n",dp->d_ino,dp->d_name); dp=readdir(p); } } Output:
"di.c" [New] 21L, 239C written [test1@localhost test1]$ cc di.c [test1@localhost test1]$ ./a.out 1049278.
442373.. 1049279.kde 1049364.aa.c.swp 1049285.balan.sh.swp
1049387ar.sh 1049404firstfit.c 1049403wai.c 1049406sta1.c 1049405di.c RESULT:
EX.NO: 2. UNIX I/O SYSTEM CALLS - STAT, OPEN, CLOSE, EXIT Aim :
To implement UNIX I/O system calls open, read , write etc. Algorithm:
1. Create a new file using creat command (Not using FILE pointer).
2. Open the source file and copy its content to new file using read and write command. 3. Find size of the new file before and after closing the file using stat command. Program: #include<stdio.h> #include<sys/types.h> #include<sys/stat.h> #include<unistd.h> #include<fcntl.h> main() { int fd1,fd2,n; char source[30],ch[5]; struct stat s,t,w; fd1=creat("test.txt",0644);
printf("Enter the file to be Copied\n"); scanf("%s",source);
fd2=open(source,0); if(fd2==-1)
{
perror("file doesnot exist"); exit(0); } while((n=read(fd2,ch,1))>0) write(fd1,ch,n); close(fd2); stat(source,&s);
printf("Source file size=%d\n",s.st_size); fstat(fd1,&t);
printf("Destination File size before closing=%d\n",t.st_size); close(fd1);
fstat(fd1,&w);
printf("Destination File Size after closing=%d\n",w.st_size); }
Sample Output:
[test1@localhost test1]$ cc sta1.c [test1@localhost test1]$ ./a.out
Enter the file to be Copied sta1.c
Source file size=670
Destination File size before closing=670 Destination File Size after closing=3 [test1@localhost test1]$
EX: NO: 3. SIMULATION OF UNIX COMMANDS USING C Aim :
To simulate the UNIX command ls. Algorithm :
1. Import dir.h header file
2. Create directory structure variable
3. Using findfirst and findnext methods display the files available in the current directory. Program: #include <stdio.h> #include <dir.h> #include<conio.h> char dir[MAXDIR]; void main(void) { struct ffblk ffblk; int done; clrscr(); printf("Directory listing of *.*\n"); done = findfirst("*.*",&ffblk,0); while (!done) { printf(" %s\n", ffblk.ff_name); done = findnext(&ffblk); } getch(); }
GREP
Aim : To simulate the UNIX command grep. Algorithm :
1. Create a file with some content. 2. Get any one pattern / string as a input
3. Read file content as strings and compare it with the input pattern
4. If pattern match with file string or part of the string then print that string / line. 5. Close the file.
Program: #include<stdio.h> #include<conio.h> #include<string.h> void main() { FILE *fptr; char ch; int i; char p[10], a[50]; clrscr(); fptr=fopen("input.txt","w");
printf("Enter the data to be stored in the file\n"); scanf("%c",&ch); while(ch!='$') { fprintf(fptr,"%c",ch); scanf("%c",&ch); } fclose(fptr);
printf("Enter the pattern to be searched"); scanf("%s",p); fptr=fopen("input.txt","r"); i=0; while(!feof(fptr)) { ch=getc(fptr); if( ch!='\n') a[i] = ch; else { a[i]='\0'; if(strnicmp(a,p,strlen(p))==0) printf("%s\n",a);
i=-1; } i++; } fclose(fptr); getch(); } Sample Output:
Enter the data to be stored in the file India Country welcome sit well $
Enter the pattern to be searched wel
welcome well
EX: NO: 4 SCHEDULING ALGORITHMS – FCFS AND SJF Aim:
To compute average waiting time and average turnaround time and to draw Gantt chart using FCFS and SJF
FCFS SCHEDULING ALGORITHM Algorithm :
1. Get the no of processes.
2. For each process assign the process id and get the process time.
3. Set the waiting time of the first process as 0 and its turn around time as process time. 4. For each process calculate,
Waiting time of process(n) = waiting time of process (n-1) + process time of process (n-1) Turn around time of process(n) = waiting time of process (n) + process time of process (n) 5. Calculate the average waiting time and turn around time.
6. Print the Gantt chart. Program: #include<stdio.h> #include <conio.h> #include<graphics.h> struct pro { int pid,pt,wt,tat; }; void main() { struct pro p[10]; int n,i,twt,ttat,j,k; float awt,atat; char s[5],e[5]; clrscr();
printf("Enter the no of process\n"); scanf("%d",&n);
for(i=1;i<=n;i++) {
p[i].pid=i;
printf("Enter the processing time of %d process\n",i); scanf("%d",&p[i].pt);
}
p[1].tat=p[1].pt; twt=p[1].wt; ttat=p[1].tat; for(i=2;i<=n;i++) { p[i].wt=p[i-1].wt+p[i-1].pt; p[i].tat=p[i].wt+p[i].pt; twt=twt+p[i].wt; ttat=ttat+p[i].tat; }
printf("PROCESSID PROCESSTIME WAITINGTIME TURNTIME\n"); for(i=1;i<=n;i++)
{
printf("%d\t %d\t %d \t%d\n",p[i].pid,p[i].pt,p[i].wt,p[i].tat); }
printf("TOTAL WAITING TIME %d\n",twt);
printf("TOTAL TURN AROUND TIME %d\n",ttat); awt=(float)twt/n;
atat=(float)ttat/n;
printf("AVERAGE WAITING TIME %f\n",awt);
printf("AUERAGE TURN AROUND TIME %f\n",atat); printf(“\nGantt chart \n”); for(i=1;i<=p[n].wt+p[n].pt;i++) printf(" %c",'-'); printf("\n"); for(i=1;i<=n;i++) { j=p[i].wt; printf(" %*d",j,p[i].wt); } for(i=1;i<=p[n].wt;i++) printf(" "); printf("%d",p[n].wt+p[n].pt); printf("\n"); for(i=1;i<=p[n].wt+p[n].pt;i++) printf(" %c",'-'); getch(); } Sample Output:
Enter the no of process 3
4
Enter the processing time of 2 process 5
Enter the processing time of 3 process 6
PROCESSID PROCESSTIME WAITINGTIME TURNTIME
1 4 0 4
2 5 4 9
3 6 9 15
TOTAL WAITING TIME 13 TOTAL TURN AROUND TIME 28 AVERAGE WAITING TIME 4.333333 AUERAGE TURN AROUND TIME 9.333333
Gant Chart - - - 0 4 9 15 - - - SJF SCHEDULING ALGORITHM Algorithm :
1. Get the no of processes.
2. For each process assign the process id and get the process time. 3. Sort the processes according to the process time.
4. Set the waiting time of the first process as 0 and its turn around time as process time 5. For each process calculate,
Waiting time of process(n) = waiting time of process (n-1) + process time of pocess(n-1) Turn around time of process(n) = waiting time of process (n) + process time of process (n) 6. Calculate the average waiting time and turn around time
7. Print the Gantt chart. Program: #include <stdio.h> #include<conio.h> struct pro { int pid; int pt; int wt; int tat; }; void main() { struct pro p[10],t;
int n,i,j,twt,ttat,k; float awt,atat; clrscr();
printf("enter the no of process\n"); scanf("%d",&n);
for(i=1;i<=n;i++) {
p[i].pid=i;
printf("enter the processing time of %d process\n",i); scanf("%d",&p[i].pt); } for(i=1;i<n;i++) for(j=i+1;j<=n;j++) if(p[i].pt>=p[j].pt) { t=p[i]; p[i]=p[j]; p[j]=t; } p[1].wt=0; p[1].tat=p[1].pt; twt=p[1].wt; ttat=p[1].tat; for(i=2;i<=n;i++) { p[i].wt=p[i-1].wt+p[i-1].pt; p[i].tat=p[i].wt+p[i].pt; twt=twt+p[i].wt; ttat=ttat+p[i].tat; }
printf("PROCESSID PROCESSTIME WAITINGTIME TURNTIME\n"); for(i=1;i<=n;i++)
{
printf("%d %d %d %d\n",p[i].pid,p[i].pt,p[i].wt,p[i].tat); }
printf("TOTAL WAITING TIME %d\n",twt);
printf("TOTAL TURN AROUND TIME %d\n",ttat); awt=(float)twt/n;
atat=(float)ttat/n;
printf("AVERAGE WAITING TIME %f\n",awt);
printf("AUERAGE TURN AROUND TIME %f\n",atat); printf("\nGantt chart \n");
for(i=1;i<=p[n].wt+p[n].pt;i++) printf(" %c",'-');
for(i=1;i<=n;i++) { j=p[i].wt; printf("%*d",j,p[i].wt); } for(i=1;i<=p[n].wt;i++) printf(" "); printf("%d",p[n].wt+p[n].pt); printf("\n"); for(i=1;i<=n;i++) { j=p[i].wt; printf(" %*dp",j,p[i].pid); } printf("\n"); for(i=1;i<=p[n].wt+p[n].pt;i++) printf(" %c",'-'); getch(); } Sample Output
Enter the no of process 3
Enter the processing time of 1 process 6
Enter the processing time of 2 process 3
Enter the processing time of 3 process 7
PROCESSID PROCESSTIME WAITINGTIME TURNTIME 2 3 0 3 1 6 3 9 3 7 9 16 TOTAL WAITING TIME 12
TOTAL TURN AROUND TIME 28 AVERAGE WAITING TIME 4.000000 AUERAGE TURN AROUND TIME 9.333333 Gantt chart - - - 0 3 9 16 2p 1p 3p - - - RESULT:
EX: NO: 5 SCHEDULING ALGORITHMS – PRIORITY AND ROUND ROBIN Aim:
To compute average waiting time and average turnaround time and to draw Gantt chart using priority and round robin scheduling algorithms.
PRIORITY SCHEDULING ALGORITHM Algorithm :
1. Get the no of processes.
2. For each process assign the process id and get the process time and the priority value. 3. Sort the processes according to the priority value.
4. Set the waiting time of the first process as 0 and its turn around time as process time. 5. For each process calculate,
Waiting time of process(n) = waiting time of process (n-1) + process time of process(n-1) Turn around time of process(n) = waiting time of process(n) + process time of process (n) 6. Calculate the average waiting time and turn around time.
Program : #include <stdio.h> #include <conio.h> struct pro { int pid; int pr; int pt; int wt; int tat; }; void main() { struct pro p[10],t; int n,i,j,twt,ttat; float awt,atat; clrscr();
printf("enter the no of process\n"); scanf("%d",&n);
for(i=1;i<=n;i++) {
p[i].pid=i;
printf("enter the processing time & priority of %d process\n",i); scanf("%d %d",&p[i].pt,&p[i].pr);
for(i=1;i<n;i++) for(j=i+1;j<=n;j++) if(p[i].pr<=p[j].pr) { t=p[i]; p[i]=p[j]; p[j]=t; } p[1].wt=0; p[1].tat=p[1].pt; twt=p[1].wt; ttat=p[1].tat; for(i=2;i<=n;i++) { p[i].wt=p[i-1].wt+p[i-1].pt; p[i].tat=p[i].wt+p[i].pt; twt=twt+p[i].wt; ttat=ttat+p[i].tat; }
printf("PROCESSID PROCESSTIME PRIORITY WAITINGTIME TURNTIME\n");
for(i=1;i<=n;i++) {
printf("%d %d %d %d %d\n",p[i].pid,p[i].pt,p[i].pr,p[i].wt,p[i].tat); }
printf("TOTAL WAITING TIME %d\n",twt);
printf("TOTAL TURN AROUND TIME %d\n",ttat); awt=(float)twt/n;
atat=(float)ttat/n;
printf("AVERAGE WAITING TIME %f\n",awt);
printf("AUERAGE TURN AROUND TIME %f\n",atat); getch();
}
Sample Output :
enter the no of process : 4
enter the burst time for process 1 : 3 enter the priority for process 1 : 8 enter the burst time for process 2 : 4 enter the priority for process 2 : 9 enter the burst time for process 3 : 2 enter the priority for process 3 : 8 enter the burst time for process 4 : 4 enter the priority for process 4 : 1
process id priority burst time waiting time turn around time
4 1 4 0 4
3 8 2 4 6
1 8 3 6 9
2 9 4 9 13 total waiting time : 19
total turn around time : 32 average waiting time : 4.75 average turn around time : 8
ROUND ROBIN SCHEDULING ALGORITHM Algorithm :
1. Accept the no of processes in the ready queue and time slice. 2. For each process in the ready queue accept the burst time. 3. Calculate the no of time slices required for each process.
4. If the burst time is less than the time slice then the no of time slice is 1. 5. Considering the ready queue as a circular queue, calculate
Total waiting time for process(n) = waiting time for process (n-1) + burst time of process (n-1) + the time difference in getting the CPU from process(n). Total turn around time for process(n) = waiting time for process (n) + burst time of
process (n) + the time difference in getting the CPU from process(n). 6. Calculate the average waiting time and turn around time.
Program : #include <stdio.h> #include <conio.h> struct pro { int pid; int pt; int rt; int st; int et; int seen; int wt; int tat; }; void main()
{
struct pro p[10];
int n,i,ct=0,ts,twt,ttat,q[30],r=0,f=1; float awt,atat;
clrscr();
printf("\nenter the no of process:"); scanf("%d",&n);
printf("\nenter the value of time slice:"); scanf("%d",&ts);
for(i=1;i<=n;i++) {
p[i].pid=i;
printf("\nenter the processing time of %d process:",i); scanf("%d",&p[i].pt); p[i].rt=p[i].pt; p[i].seen=0; r++; q[r]=p[i].pid; } printf("PRID PT ST ET RT\n"); p[q[f]].wt=0; p[q[f]].st=ct; p[q[f]].et=ct+ts; p[q[f]].rt=p[q[f]].rt-ts; p[q[f]].seen=1; if (p[q[f]].rt>0) { r++; q[r]=q[f]; } printf("%d %d %d %d %d\n",q[f],p[q[f]].pt,p[q[f]].st, p[q[f]].et,p[q[f]].rt); f++; ct=ts; while (r>=f) { if(p[q[f]].seen==0) { p[q[f]].wt=p[q[f]-1].wt+ts; p[q[f]].seen=1; } else { p[q[f]].wt=p[q[f]].wt+ct-p[q[f]].et; } p[q[f]].st=ct; p[q[f]].et=ct+ts;
p[q[f]].rt=p[q[f]].rt-ts; if (p[q[f]].rt>0) { r++; q[r]=q[f]; } ct=ct+ts; printf("%d %d %d %d %d\n",q[f],p[q[f]].pt,p[q[f]].st, p[q[f]].et,p[q[f]].rt); f++; } for(i=1;i<=n;i++) {
printf("\nwaiting time of %d process is %d:",i,p[i].wt); }
getch(); }
Sample Output :
Enter the no of process : 2 Enter the value of time slice : 5
Enter the processing time of process 1 : 10 Enter the processing time of process 2 : 5
PRID PT ST ET RT
1 10 0 5 5 2 5 5 10 0 1 10 10 15 0 Average Waiting time = 7.5
EX:NO: 6 INTERPROCESS COMMUNICATION Aim : To implement interprocess communication using pipe command. Algorithm :
1. Start
2. Create a child and parent using fork()
3. Allow communication between both the process 4. Stop Program : #include<stdio.h> main() { int p[2],pid,pid1; char msg[25],msg1[25]; pipe(p); pid=fork(); if(pid!=0) { sleep(2); read(p[0],msg1,21); printf(“%s”,msg1); } else { pid1=fork(); if(pid1!=0); { sleep(1); read(p[0],msg1,21);
write(p[1],”Grand child says hello”,21); }
else
write(p[1],”Says hello to grandpa”,29); }
}
Sample Output;
Says hello to grandpaX@ RESULT:
EX:NO :7 PRODUCER- CONSUMER PROBLEM Aim : To implement the Producer- Consumer problem using semaphores. Algorithm :
5. Create two functions called producer and consumer. 6. Set semaphore variable as 1.
7. When producer active set the semaphore variable as 1 and allow producer to put data into the buffer and don’t allow consumer to consume anything.
8. After producer complete the process release the semaphore and signal the consumer. 9. When consumer active again set the semaphore variable as 1 and allow the consumer
to get data from buffer and don’t allow the producer to add data.
10. After the consumer taken release the semaphore variable and signal the producer. Program :
#include<stdio.h> #include<conio.h>
int n_semaphore=0; // keep track of no of item in the buffer int s_semaphore=1; // to enforce mutual exclusion char s;
void producer() {
s_semaphore=0; // set semaphore to avoid access to consumer if(!s_semaphore)
printf("Now producer can add data to buffer\n"); else
printf("Critical Region \n");
s_semaphore=1; // release semaphore
signal_c(); // call to consumer
}
void consumer() {
buffer_check(); // check buffer is empty or not
s_semaphore=0; // set semaphore to avoid access to producer if(!s_semaphore)
printf("Consumer takes from the buffer\n"); else
printf("Critical Region \n");
s_semaphore=1; // release semaphore
signal_p(); // call to producer
}
signal_c() {
n_semaphore=n_semaphore+1; consumer(); return 0; } signal_p() { n_semaphore=n_semaphore-1; printf("Enter n to stop\n"); scanf("%c",&s); if(s=='n') exit(); return 0; } buffer_check() { if(n_semaphore<=0) { printf("Buffer is empty\n"); exit(); } return 0; } void main() { clrscr(); n_semaphore=0; while(1) { producer(); } } Sample Output;
Now producer can add data to buffer Consumer takes from the buffer Enter n to stop
Now producer can add data to buffer Consumer takes from the buffer Enter n to stop
n
RESULT:
Aim:
To implement Fixed Partition Memory Management Scheme. Algorithm:
1. Get the number of pages and their sizes.
2. Create pages with corresponding sizes using linked list as free nodes.
3. Get the number of programs <= number of pages to be allocated and their sizes. 4. Start with the first page, if the first program size fits with this page then allocate first
page for the first program. Otherwise check with next program and so on. 5. Continue the process with next pages.
6. Maintain the allotted pages as a separate linked list.
7. Calculate internal fragmentation – balance spaces in each page and external fragmentation – sizes of unallocated pages.
8. Display the starting and ending address of Free nodes and allotted nodes and also the internal and external fragmentations.
Program: #include<stdio.h> #include<conio.h> struct node { int size; int busy; int pid;
struct node *start, *end, *next; };
struct node *freenode=NULL, *allotnode=NULL, *newnode, *temp1=NULL, *temp2=NULL, *anode;
int internal=0, external=0;
int no_of_pages, size[20], allot[10]={0}; int no,np,x,y,t=0; void partition(); void allocate(); void display(); void main() { int ch; clrscr(); while(1) {
printf("\n \nEnter the choice: \n 1.Partition \n 2.Allocate \n 3.Display \n 4.Exit \n"); scanf("%d",&ch);
switch(ch) { case 1: partition(); break; case 2: allocate(); break; case 3: display(); break; case 4: exit(0); break; default: printf("Wrong Choice"); break; } } } void partition() { int addr;
printf("\nEnter the no of pages\n"); scanf("%d",&no_of_pages);
printf("\nEnter the page sizes in Bytes\n "); for(no=0;no<no_of_pages;no++)
{
scanf("%d",&size[no]); addr=(int *)malloc(size[no]);
newnode=(struct node *)malloc(sizeof(struct node)); newnode->start=addr; newnode->end=addr+size[no]; newnode->size=size[no]; newnode->busy=0; newnode->pid=0; newnode->next=NULL; if(freenode==NULL) freenode=newnode; else { temp1=freenode; while(temp1->next!=NULL) temp1=temp1->next;
temp1->next=newnode; } } } void allocate() {
int no_of_prog, sizep[20];
anode=(struct node *)malloc(sizeof(struct node)); do
{
printf("\nEnter the number of programs<= %d\n",no_of_pages); scanf("%d",&no_of_prog);
}
while(no_of_prog > no_of_pages);
printf("\nEnter the program sizes in Bytes\n"); for(np=0;np<no_of_prog;np++)
scanf("%d",&sizep[np]);
//Program to allocate the pages to the programs using firstfit temp1=freenode;
while(temp1 != NULL) {
for(y=0;y<no_of_prog;y++) {
if(temp1->size>=sizep[y] && temp1->busy==0 && allot[y]==0) { temp1->busy=1; allot[y]=1; anode->pid=y+1; anode->busy=1; anode->size=temp1->size; anode->start=temp1->start; t=(int)temp1->start; anode->end=t+sizep[y]-1; anode->next=NULL; internal+=temp1->size-sizep[y]; if(allotnode==NULL) allotnode=anode; else { temp2=allotnode; while(temp2->next!=NULL) temp2=temp2->next; temp2->next=anode; }
} }
printf("Proces id %d \n",allotnode->pid); printf("Start addr %u \n",allotnode->start); printf("End addr %u \n\n",allotnode->end); if(temp1->busy==0)
external+=temp1->size; temp1=temp1->next;
}
printf("Internal Fragmentation = %d\n",internal); printf("External Fragmentation = %d\n",external); }
void display() {
temp1=freenode;
printf("\n\nFree nodes are\n\n\n"); while(temp1!=NULL)
{
if((temp1->busy)==0) {
printf("Start addr %u \n",temp1->start); printf("End addr %u \n",temp1->end); printf("Size %d \n",temp1->size); } temp1=temp1->next; } } Sample Output: Enter the choice: 1.Partition 2.Allocate 3.Display 4.Exit 1
Enter the no of pages 3
Enter the page sizes in Bytes 20
40 60
Enter the choice: 1.Partition 2.Allocate 3.Display 4.Exit 3
Free nodes are Start addr 2310 Endaddr 2330 Size 20 Start addr 2350 Endaddr 2390 Size 40 Start addr 2410 Endaddr 2470 Size 60
Enter the choice: 1.Partition 2.Allocate 3.Display 4.Exit 2
Enter the number of programs<= 3 3
Enter the program sizes in Bytes 15 30 70 Proces id 1 Start addr 2310 End addr 2324 Proces id 2 Start addr 2350 End addr 2379 Proces id 2 Start addr 2350
End addr 2379
Internal Fragmentation = 15 External Fragmentation = 60 Enter the choice:
1.Partition 2.Allocate 3.Display 4.Exit 4 RESULT:
EX:NO :9 MEMORY MANAGEMENT – VARIABLE PARTITION Aim:
To implement Variable Partition Memory Management Scheme. Algorithm:
1. Get the number of bytes for the memory and allocate a common space.
2. Partition the memory according to the process id and the request memory size from the user one by one until the memory is full.
3. After the process finishes, the memory is deallocated and any other process can use this.
4. When deallocating the memory, if any two consecutive partitions are free merge them as a single partition.
5. Allocate the process in partitions according to the process sizes. Balance space in that partition is treated as a separate partition or merge with the nearby partition if that is free.
6. Display the starting and ending address of Free nodes and allotted nodes. Program: #include<stdio.h> #include<conio.h> struct allotnode { int *startaddr; int pid;
int flag; //it indicates whether the block is empty or not , if it is 1 then the block is busy int *endaddr;
struct allotnode *next; }; void partition(); void allocate(); void Deallocate(int); void Merge(); void print(); int block_size,*addr,t; double up_size;
struct allotnode *headallot=NULL,*node1=NULL,*node2=NULL,*temp,*freenode; void main()
{ int id; int choice; clrscr();
scanf("%d",&block_size);
addr = (int *) calloc(block_size,1);
freenode = (struct allotnode *)malloc(sizeof(struct allotnode)); freenode->flag=0; freenode->pid=0; freenode->startaddr=addr; freenode->endaddr=addr+(block_size/2); freenode->next=NULL; while(1) {
printf("Enter the choice \n 1.Partition \n 2.To Allocate \n 3.To Print \n 4.To Deallocate \n 5.Exit \n"); scanf("%d",&choice); switch(choice) { case 1 : partition(); break; case 2: allocate(); break; case 3: print(); break; case 4:
printf("Enter the process id which you want to Deallocate \n"); scanf("%d",&id); Deallocate(id); break; case 5: exit(0); break; } } } void partition() { int size;
node1 = (struct allotnode *)malloc(sizeof(struct allotnode)); printf("Enter the process id\n");
scanf("%d",&node1->pid);
printf("Enter the size of the proces"); scanf("%d",&size);
node1->next=freenode; node1->flag=1; if(((int)freenode->endaddr-(int)freenode->startaddr)>=size) { if(headallot==NULL) { headallot=node1; node1->startaddr=addr; t=addr+(size/2); node1->endaddr=t-1; } else { node2->next=node1; t=(int)node2->endaddr; node1->startaddr=t+1; node1->endaddr=t+size; } node2=node1; t=node2->endaddr; freenode->startaddr=t+1; } else printf("Less Memory ! \n\n\n"); } void allocate() { int pid,size,allot=0;
node1 = (struct allotnode *)malloc(sizeof(struct allotnode)); printf("Enter the process id\n");
scanf("%d",&pid);
printf("Enter the size of the proces"); scanf("%d",&size);
temp=headallot; while(temp != NULL) {
if(temp->flag==0 && ((int)temp->endaddr - (int)temp->startaddr)>=size && allot==0) {
temp->flag=1; temp->pid=pid; allot=1;
node1->flag=0; node1->endaddr=temp->endaddr; temp->endaddr=(int)temp->startaddr+size-1; node1->startaddr=(int)temp->endaddr+1; node1->next=temp->next; temp->next=node1; } temp=temp->next; } } void print() { temp=headallot;
printf("\n\nAllocated nodes are\n\n\n"); while(temp != NULL)
{
if(temp->flag==1) {
printf("start addr %d \n",temp->startaddr); printf("pid %d \n",temp->pid);
printf("end addr %d \n\n\n",temp->endaddr); }
temp=temp->next; }
temp=headallot;
printf("\n\nFree nodes are\n\n\n"); while(temp != NULL)
{
if(temp->flag==0) {
if(temp->startaddr == temp->endaddr) printf("\n No Free nodes \n"); else
{ printf("start addr %d \n",temp->startaddr); printf("end addr %d \n\n\n",temp->endaddr); }
}
temp=temp->next; }
}
void Deallocate(int id) {
while(temp!=NULL) { if(temp->pid==id) { temp->pid=0; temp->flag=0; } else
printf("\nProcess not available\n"); temp=temp->next; } Merge(); } void Merge() { int f=0; temp=headallot; while(temp!=NULL) {
if(temp->flag==0 && temp->next->flag==0) { temp->endaddr=temp->next->endaddr; temp->next=temp->next->next; f=1; } temp=temp->next; } if(f==1) Merge(); } Sample Output:
Enter the Block size 100
Enter the choice 1.Partition 2.To Allocate 3.To Print 4.To Deallocate 5.Exit 1
Enter the process id 1
Enter the size of the process 20
Enter the choice 1.Partition 2.To Allocate 3.To Print 4.To Deallocate 5.Exit 1
Enter the process id 2
Enter the size of the process 40
Enter the choice 1.Partition 2.To Allocate 3.To Print 4.To Deallocate 5.Exit 3
Allocated nodes are start addr 2296 pid 1 end addr 2315 start addr 2216 pid 2 end addr 2355 Free nodes are start addr 2256 end addr 2396
Enter the choice 1.Partition 2.To Allocate 3.To Print 4.To Deallocate 5.Exit 2
Enter the process id 3
Enter the size of the proces 30
Enter the choice 1.Partition 2.To Allocate 3.To Print 4.To Deallocate 5.Exit 3
Allocated nodes are start addr 2296 pid 1 end addr 2315 start addr 2216 pid 2 end addr 2355 start addr 2256 pid 3 end addr 2385 Free nodes are start addr 2286 end addr 2396 Enter the choice 1.Partition 2.To Allocate 3.To Print 4.To Deallocate
5.Exit 4
Enter the process id which you want to Deallocate 2
Enter the choice 1.Partition 2.To Allocate 3.To Print 4.To Deallocate 5.Exit 3
Allocated nodes are start addr 2296 pid 1 end addr 2315 start addr 2256 pid 3 end addr 2385 Free nodes are start addr 2216 end addr 2355 start addr 2286 end addr 2396 Enter the choice 1.Partition 2.To Allocate 3.To Print 4.To Deallocate 5.Exit 2
Enter the process id 2
Enter the size of the process 10
Enter the choice 1.Partition 2.To Allocate
3.To Print 4.To Deallocate 5.Exit
3
Allocated nodes are start addr 2296 pid 1 end addr 2315 start addr 2316 pid 2 end addr 2325 start addr 2256 pid 3 end addr 2385 Free nodes are RESULT: start addr 2226 end addr 2355 start addr 2286 end addr 2396
