TUTORIAL : 5 Parallel Processing
1. WHAT
IS CONTENTION? DEMONSTRATE CONCEPT OF CONTENTION BY WRITING C PROGRAM
#include<stdio.h>
#include"pheader.h"
int main()
{
int shmidi,id,*i;
i=sharei(4,&shmidi);
*i=5;
id=process_fork(2);
*i=*i+1;
printf("%d = %d
\t i = %d \n",id,*i);
process_join(id,2);
cleanup_memory(&shmidi);
}
OUTPUT:
1 = 6 I = 1234514217
0 = 7 I = 1234514217
2. WRITE PROGRAM TO
ADD 10 ELEMENT OF ARRAY USING SEMAPHORE.
Header.h
#include<stdio.h>
#include<stdlib.h>
#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/shm.h>
#include<sys/sem.h>
void spin_lock_init(int *lok)
{
int
init_sem_value=1;
*lok=semget(IPC_PRIVATE,1,(0600|IPC_CREAT));
if(*lok==-1)
{
printf("Error in semget...");
exit(1);
}
if(semctl(*lok,0,SETVAL,init_sem_value)<0)
{
printf("Error in semctl...");
exit(1);
}
}
void spin_lock(int *lok)
{
struct sembuf
sembuffer, *sops;
sops=&sembuffer;
sops->sem_num=0;
sops->sem_op=-1;
sops->sem_flg=0;
if(semop(*lok,sops,1)<0)
{
printf("semop lock error...");
exit(1);
}
}
void spin_unlock(int *lok)
{
struct sembuf
sembuffer, *sops;
sops=&sembuffer;
sops->sem_num=0;
sops->sem_op=1;
sops->sem_flg=0;
if(semop(*lok,sops,1)<0)
{
printf("semop lock error...");
exit(1);
}
}
Sema_add.c
#include<stdio.h>
#include"head.h"
#include”pheader.h”
int main()
{
int
shmidlw1,shmidlw2,shidlw2,shmidi,shmidfsum,a[10],sum=0,*final_sum,id,*i,j,sep_i,*lw1,*lw2;
for(j=0;j<10;j++)
{
printf("Enter The Value Of Element[%d] = ",j+1);
scanf("%d",&a[j]);
}
i=sharei(4,&shmidi);
lw1=sharei(4,&shmidlw1);
lw2=sharei(4,&shmidlw2);
final_sum=sharei(4,&shmidfsum);
*i=-1;
*final_sum=0;
spin_lock_init(lw1);
spin_lock_init(lw2);
id=process_fork(2);
up:
spin_lock(lw1);
*i=*i+1;
sep_i=*i;
spin_unlock(lw1);
if(sep_i>9)
{
goto down;
}
else
{
sum+=a[sep_i];
goto up;
}
down:
spin_lock(lw2);
*final_sum+=sum;
spin_unlock(lw2);
process_join(id,2);
printf("Result = %d \n",*final_sum);
cleanup_memory(&shmidi);
cleanup_memory(&shmidlw1);
cleanup_memory(&shmidlw2);
cleanup_memory(&shmidfsum);
}
OUTPUT:
Enter The Value
of Element[1] = 1
Enter The Value
of Element[2] = 2
Enter The Value
of Element[3] = 3
Enter The Value
of Element[4] = 4
Enter The Value
of Element[5] = 5
Enter The Value
of Element[6] = 6
Enter The Value
of Element[7] = 7
Enter The Value
of Element[8] = 8
Enter The Value
of Element[9] = 9
Enter The Value
of Element[10] = 10
Result = 55
