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#include <stdio.h>
#include <stdlib.h>
#include <time.h>
// 256 bytes = 4 * 64 = 4 * cachelines
// with 4-way associative cache one row
// traverse each set.
// With 8-way associative cache the col number
// should be doubled.
#define COLS 256
#define ROWS 1024
#define VFL 6291456
#ifndef OFF
#define OFF 0
#endif
char arr[ROWS][COLS+OFF*4] __attribute__((aligned(4096)));
char arr2[VFL];
int main() {
int i, j, k;
time_t t;
volatile int xor;
srand(0x42069);
// init array with random values
for (i = 0; i < ROWS; i++) {
for (j = 0; j < COLS; j++) {
arr[i][j] = rand()%255;
}
}
// "flush" 6MiB cache
// for(i = 0; i < VFL; i++)arr2[i] = i*i;
// for(i = 0; i < VFL; i++)arr2[i] += 1;
// mem barrier
__sync_synchronize();
t = clock();
for (i = 1; i < ROWS; i++) {
for (j = 0; j < COLS; j++) {
arr[i][j] *= arr[i-1][j];
xor ^= arr[i][j];
}
}
t = clock() - t;
printf("%ld",t);
}
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