#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>


#define N 20240
#define SIZE 4096

int main()
{
  int k;
  for(k = 0; k < 10; k++) {
    int i = 0;
    int pid;
    unsigned char *mem = mmap(0, N*SIZE, PROT_READ|PROT_WRITE,
  			MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
    if(mem == MAP_FAILED)
      perror("mmap");
    printf("pagesize: %d\n", getpagesize());
    for(i = 0; i < N; i++)
      mem[i*SIZE] = i*1000000007ul;
    printf("pages allocated\n");
    pid = fork();
    if(pid == 0) {
      /* child */
      for(i = 0; i < N; i++)
        mem[i*SIZE+1] = i;          /* force copy */
      printf("copy complete\n");
      exit(0);
    } else if(pid == -1) {
      perror("fork");
    } else {
      /* parent */
      waitpid(pid, NULL, 0);
    }
    munmap(mem, N*SIZE);
  }
}