src/memtest.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <assert.h>
   5 #include <limits.h>
   6 #include <errno.h>
   7
   8 #if (ULONG_MAX == 4294967295UL)
   9 #define MEMTEST_32BIT
  10 #elif (ULONG_MAX == 18446744073709551615ULL)
  11 #define MEMTEST_64BIT
  12 #else
  13 #error "ULONG_MAX value not supported."
  14 #endif
  15
  16 /* Fill words stepping a single page at every write, so we continue to
  17  * touch all the pages in the smallest amount of time reducing the
  18  * effectiveness of caches, and making it hard for the OS to transfer
  19  * pages on the swap. */
  20 void memtest_fill(unsigned long *l, size_t bytes) {
  21     unsigned long step = 4096/sizeof(unsigned long);
  22     unsigned long words = bytes/sizeof(unsigned long)/2;
  23     unsigned long iwords = words/step;  /* words per iteration */
  24     unsigned long off, w, *l1, *l2;
  25
  26     assert((bytes & 4095) == 0);
  27     for (off = 0; off < step; off++) {
  28         l1 = l+off;
  29         l2 = l1+words;
  30         for (w = 0; w < iwords; w++) {
  31 #ifdef MEMTEST_32BIT
  32             *l1 = *l2 = ((unsigned long)     (rand()&0xffff)) |
  33                         (((unsigned long)    (rand()&0xffff)) << 16);
  34 #else
  35             *l1 = *l2 = ((unsigned long)     (rand()&0xffff)) |
  36                         (((unsigned long)    (rand()&0xffff)) << 16) |
  37                         (((unsigned long)    (rand()&0xffff)) << 32) |
  38                         (((unsigned long)    (rand()&0xffff)) << 48);
  39 #endif
  40             l1 += step;
  41             l2 += step;
  42         }
  43     }
  44 }
  45
  46 void memtest_compare(unsigned long *l, size_t bytes) {
  47     unsigned long words = bytes/sizeof(unsigned long)/2;
  48     unsigned long w, *l1, *l2;
  49
  50     assert((bytes & 4095) == 0);
  51     l1 = l;
  52     l2 = l1+words;
  53     for (w = 0; w < words; w++) {
  54         if (*l1 != *l2) {
  55             printf("\n*** MEMORY ERROR DETECTED: %p != %p (%lu vs %lu)\n",
  56                 (void*)l1, (void*)l2, *l1, *l2);
  57             exit(1);
  58         }
  59         l1 ++;
  60         l2 ++;
  61     }
  62 }
  63
  64 void memtest_test(size_t megabytes, int passes) {
  65     size_t bytes = megabytes*1024*1024;
  66     unsigned long *m = malloc(bytes);
  67     int pass = 0;
  68
  69     if (m == NULL) {
  70         fprintf(stderr,"Unable to allocate %zu megabytes: %s",
  71             megabytes, strerror(errno));
  72         exit(1);
  73     }
  74     while (pass != passes) {
  75         pass++;
  76         printf("PASS %d... ", pass);
  77         fflush(stdout);
  78         memtest_fill(m,bytes);
  79         memtest_compare(m,bytes);
  80         printf("ok\n");
  81     }
  82 }
  83
  84 void memtest(size_t megabytes, int passes) {
  85     memtest_test(megabytes,passes);
  86     printf("\nYour memory passed this test.\n");
  87     printf("Please if you are stil in doubt use the following two tools:\n");
  88     printf("1) memtest86: http://www.memtest86.com/\n");
  89     printf("2) memtester: http://pyropus.ca/software/memtester/\n");
  90     exit(0);
  91 }