dramerr.c

/* The following is a simple program to check for memory corrections in
 * DRAM with ECC switched off. Accordingly to recend large scale studies
 * such as http://www.cs.toronto.edu/~bianca/papers/sigmetrics09.pdf
 * the error rate is of 25,000-75,000 errors per billion hours per Mbit.
 *
 * If this is true you should see at least one error after a few days
 * running this program at max in a computer without ECC.
 *
 * Compile with: gcc -O2 -Wall -W -o dramerr dramerr.c
 *
 * For feedbacks: antirez@gmail.com */

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

/* It's more likely for a 0 to become 1 or the reverse, or it's just the
 * same? I don't know so I'll fill with 1010101010101010101.... */
#define PATTERN 0xAA
#define MEGABITS 8192 /* 8192 megabits are 1 gigabyte of memory */
#define BYTESPERMEGABIT 131072

int main(void) {
    unsigned char *mem = malloc(MEGABITS*BYTESPERMEGABIT);
    long j;

    if (mem == NULL) {
        printf("Sorry, can't allocate %d megabits of memory\n", MEGABITS);
        exit(1);
    }

    for (j = 0; j < MEGABITS*BYTESPERMEGABIT; j++)
        mem[j] = PATTERN;
    while(1) {
        for (j = 0; j < MEGABITS*BYTESPERMEGABIT; j++) {
            if (mem[j] != PATTERN) {
                printf("Error detected at byte %ld: %02x instead of %02x\n",
                    j, mem[j], PATTERN);
                exit(1);
            }
        }
        printf(".");
        fflush(stdout);
    }
    return 0;
}