#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#define BUFLEN 500000
#define LOOP_TIMES 500

int cmp(const void *a, const void *b) {
    double x = *(double *)a;
    double y = *(double *)b;
    if (x < y) return -1;
    if (x > y) return 1;
    return 0;
}

int main(){
        char *buf = malloc(BUFLEN);
	double *arr = malloc(sizeof(double) * LOOP_TIMES);
        size_t i,j,k;
        struct timespec tv0,tv;
	double times;

        for(j=100; j<BUFLEN; j*=2){
          for(k=0; k<LOOP_TIMES; k++){
            for (i=0; i<100; i++)
                  memset(buf+i, i, j-i);
          }
        }

        for(j=100; j<BUFLEN; j*=2){
          for(k=0; k<LOOP_TIMES; k++){
            clock_gettime(CLOCK_REALTIME, &tv0);
            for (i=0; i<100; i++)
                  memset(buf+i, i, j-i);
            clock_gettime(CLOCK_REALTIME, &tv);
            tv.tv_sec -= tv0.tv_sec;
            if ((tv.tv_nsec -= tv0.tv_nsec) < 0) {
                tv.tv_nsec += 1000000000;
                tv.tv_sec--;
            }
	    arr[k] = tv.tv_sec + (double)tv.tv_nsec/1000000000;
          }
          qsort(arr, 500, sizeof(double), cmp); 
          
	  for (int m = 100; m < LOOP_TIMES - 100; m++) {
              times += arr[m];
          }
	  printf("len: %ld  time: %.9lf\n",j, times);
	}
        free(buf);
        return 0;
}