27 lines
579 B
C
27 lines
579 B
C
|
/* accès mémoire */
|
||
|
|
#include<stdio.h>
|
||
|
|
#include<time.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
#define N 8192
|
||
|
|
|
||
|
|
int t[N][N];
|
||
|
|
|
||
|
|
static inline double tstamp(void)
|
||
|
|
{
|
||
|
|
struct timespec tv;
|
||
|
|
clock_gettime(CLOCK_REALTIME, &tv);
|
||
|
|
return tv.tv_sec + tv.tv_nsec * 1.0e-9;
|
||
|
|
}
|
||
|
|
|
||
|
|
int main()
|
||
|
|
{
|
||
|
|
int i,j;
|
||
|
|
double t1,t2;
|
||
|
|
t1=tstamp();
|
||
|
|
/* version 1 */ for(i=0;i<N;i++) for(j=0;j<N;j++) t[i][j] = 1;
|
||
|
|
/* version 2 */ // for(i=0;i<N;i++) for(j=0;j<N;j++) t[j][i] = 1; //parcours en colonne. défaut de cache donc plus long.
|
||
|
|
t2=tstamp();
|
||
|
|
printf("time = %lf\n",t2-t1);
|
||
|
|
return 0;
|
||
|
|
}
|