Why can't I use all LLC space as expected?

Question

I want to monitor and allocate LLC space usage using Intel RDT. I wrote a program which will cause 100% cache miss as I expect. My machine's LLC size is 30.25 MB, and cache line size is 64 bytes. So I access a matrix column by column like so:

int matrix[524288][16];     //4 byte * 524288 * 16 = 32M byte
void bad_access();

int main() {
    int i = 0;
    cout << sizeof(int) << endl;
    while (i < 5000) {
        bad_access();
        i++;
    }
    return 0;
}

void bad_access() {
    int sum = 0;
    for (int j = 0; j < 16; j++) {
        for (int i = 0; i < 524288; i++) {
            sum += matrix[i][j];
        }
    }
}

I assumed that the program above would use all LLC space, but when I checked it with Intel RDT, I found that it only used less than 16 MB. I wondered how that happened.