nus/cs2106/labs/lab3/progs/part3/bigsmall-par.c

102 lines
2.2 KiB
C

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include "barrier.h"
#include "config.h"
#define NUM_PROCESSES 8
int main() {
int vect[VECT_SIZE];
int pid;
int largestShmId, smallestShmId;
int *largest, *smallest;
init_barrier(NUM_PROCESSES + 1);
largestShmId =
shmget(IPC_PRIVATE, sizeof(int) * NUM_PROCESSES, IPC_CREAT | 0600);
largest = (int *)shmat(largestShmId, NULL, 0);
smallestShmId =
shmget(IPC_PRIVATE, sizeof(int) * NUM_PROCESSES, IPC_CREAT | 0600);
smallest = (int *)shmat(smallestShmId, NULL, 0);
float per_process_raw = (float)VECT_SIZE / NUM_PROCESSES;
int per_process = (int)per_process_raw;
clock_t start, end;
double time_taken;
if (per_process_raw != (float)per_process) {
printf("Vector size of %d is not divisible by %d processes.\n", VECT_SIZE,
NUM_PROCESSES);
exit(-1);
}
srand(24601);
int i;
for (i = 0; i < VECT_SIZE; i++) {
vect[i] = rand();
}
for (i = 0; i < NUM_PROCESSES; i++) {
pid = fork();
if (pid == 0)
break;
}
int j;
int big = -INT_MAX;
int small = INT_MAX;
if (pid == 0) {
int start = i * per_process;
int end = i * per_process + per_process;
for (j = start; j < end; j++) {
if (vect[j] > big)
big = vect[j];
if (vect[j] < small)
small = vect[j];
}
largest[i] = big;
smallest[i] = small;
reach_barrier();
} else {
reach_barrier();
start = clock();
for (j = 0; j < NUM_PROCESSES; j++) {
if (largest[j] > big)
big = largest[j];
if (smallest[j] < small)
small = smallest[j];
}
end = clock();
time_taken = ((double)end - start) / CLOCKS_PER_SEC;
printf("\nNumber of items: %d\n", VECT_SIZE);
printf("Smallest element is %d\n", small);
printf("Largest element is %d\n", big);
printf("Time taken is %3.2fs\n\n", time_taken);
// Clean up process table
for (j = 0; j < NUM_PROCESSES; j++)
wait(NULL);
destroy_barrier(pid);
shmdt(largest);
shmdt(smallest);
shmctl(largestShmId, IPC_RMID, 0);
shmctl(smallestShmId, IPC_RMID, 0);
}
}