tools/testing/selftests/vm/compaction_test.c

   1 /*
   2  *
   3  * A test for the patch "Allow compaction of unevictable pages".
   4  * With this patch we should be able to allocate at least 1/4
   5  * of RAM in huge pages. Without the patch much less is
   6  * allocated.
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <sys/mman.h>
  12 #include <sys/resource.h>
  13 #include <fcntl.h>
  14 #include <errno.h>
  15 #include <unistd.h>
  16 #include <string.h>
  17
  18 #define MAP_SIZE 1048576
  19
  20 struct map_list {
  21         void *map;
  22         struct map_list *next;
  23 };
  24
  25 int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
  26 {
  27         char  buffer[256] = {0};
  28         char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
  29         FILE *cmdfile = popen(cmd, "r");
  30
  31         if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
  32                 perror("Failed to read meminfo\n");
  33                 return -1;
  34         }
  35
  36         pclose(cmdfile);
  37
  38         *memfree = atoll(buffer);
  39         cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
  40         cmdfile = popen(cmd, "r");
  41
  42         if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
  43                 perror("Failed to read meminfo\n");
  44                 return -1;
  45         }
  46
  47         pclose(cmdfile);
  48         *hugepagesize = atoll(buffer);
  49
  50         return 0;
  51 }
  52
  53 int prereq(void)
  54 {
  55         char allowed;
  56         int fd;
  57
  58         fd = open("/proc/sys/vm/compact_unevictable_allowed",
  59                   O_RDONLY | O_NONBLOCK);
  60         if (fd < 0) {
  61                 perror("Failed to open\n"
  62                        "/proc/sys/vm/compact_unevictable_allowed\n");
  63                 return -1;
  64         }
  65
  66         if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
  67                 perror("Failed to read from\n"
  68                        "/proc/sys/vm/compact_unevictable_allowed\n");
  69                 close(fd);
  70                 return -1;
  71         }
  72
  73         close(fd);
  74         if (allowed == '1')
  75                 return 0;
  76
  77         return -1;
  78 }
  79
  80 int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
  81 {
  82         int fd;
  83         int compaction_index = 0;
  84         char initial_nr_hugepages[10] = {0};
  85         char nr_hugepages[10] = {0};
  86
  87         /* We want to test with 80% of available memory. Else, OOM killer comes
  88            in to play */
  89         mem_free = mem_free * 0.8;
  90
  91         fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
  92         if (fd < 0) {
  93                 perror("Failed to open /proc/sys/vm/nr_hugepages");
  94                 return -1;
  95         }
  96
  97         if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) {
  98                 perror("Failed to read from /proc/sys/vm/nr_hugepages");
  99                 goto close_fd;
 100         }
 101
 102         /* Start with the initial condition of 0 huge pages*/
 103         if (write(fd, "0", sizeof(char)) != sizeof(char)) {
 104                 perror("Failed to write to /proc/sys/vm/nr_hugepages\n");
 105                 goto close_fd;
 106         }
 107
 108         lseek(fd, 0, SEEK_SET);
 109
 110         /* Request a large number of huge pages. The Kernel will allocate
 111            as much as it can */
 112         if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
 113                 perror("Failed to write to /proc/sys/vm/nr_hugepages\n");
 114                 goto close_fd;
 115         }
 116
 117         lseek(fd, 0, SEEK_SET);
 118
 119         if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
 120                 perror("Failed to read from /proc/sys/vm/nr_hugepages\n");
 121                 goto close_fd;
 122         }
 123
 124         /* We should have been able to request at least 1/3 rd of the memory in
 125            huge pages */
 126         compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
 127
 128         if (compaction_index > 3) {
 129                 printf("No of huge pages allocated = %d\n",
 130                        (atoi(nr_hugepages)));
 131                 fprintf(stderr, "ERROR: Less that 1/%d of memory is available\n"
 132                         "as huge pages\n", compaction_index);
 133                 goto close_fd;
 134         }
 135
 136         printf("No of huge pages allocated = %d\n",
 137                (atoi(nr_hugepages)));
 138
 139         if (write(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages))
 140             != strlen(initial_nr_hugepages)) {
 141                 perror("Failed to write to /proc/sys/vm/nr_hugepages\n");
 142                 goto close_fd;
 143         }
 144
 145         close(fd);
 146         return 0;
 147
 148  close_fd:
 149         close(fd);
 150         printf("Not OK. Compaction test failed.");
 151         return -1;
 152 }
 153
 154
 155 int main(int argc, char **argv)
 156 {
 157         struct rlimit lim;
 158         struct map_list *list, *entry;
 159         size_t page_size, i;
 160         void *map = NULL;
 161         unsigned long mem_free = 0;
 162         unsigned long hugepage_size = 0;
 163         unsigned long mem_fragmentable = 0;
 164
 165         if (prereq() != 0) {
 166                 printf("Either the sysctl compact_unevictable_allowed is not\n"
 167                        "set to 1 or couldn't read the proc file.\n"
 168                        "Skipping the test\n");
 169                 return 0;
 170         }
 171
 172         lim.rlim_cur = RLIM_INFINITY;
 173         lim.rlim_max = RLIM_INFINITY;
 174         if (setrlimit(RLIMIT_MEMLOCK, &lim)) {
 175                 perror("Failed to set rlimit:\n");
 176                 return -1;
 177         }
 178
 179         page_size = getpagesize();
 180
 181         list = NULL;
 182
 183         if (read_memory_info(&mem_free, &hugepage_size) != 0) {
 184                 printf("ERROR: Cannot read meminfo\n");
 185                 return -1;
 186         }
 187
 188         mem_fragmentable = mem_free * 0.8 / 1024;
 189
 190         while (mem_fragmentable > 0) {
 191                 map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
 192                            MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
 193                 if (map == MAP_FAILED)
 194                         break;
 195
 196                 entry = malloc(sizeof(struct map_list));
 197                 if (!entry) {
 198                         munmap(map, MAP_SIZE);
 199                         break;
 200                 }
 201                 entry->map = map;
 202                 entry->next = list;
 203                 list = entry;
 204
 205                 /* Write something (in this case the address of the map) to
 206                  * ensure that KSM can't merge the mapped pages
 207                  */
 208                 for (i = 0; i < MAP_SIZE; i += page_size)
 209                         *(unsigned long *)(map + i) = (unsigned long)map + i;
 210
 211                 mem_fragmentable--;
 212         }
 213
 214         for (entry = list; entry != NULL; entry = entry->next) {
 215                 munmap(entry->map, MAP_SIZE);
 216                 if (!entry->next)
 217                         break;
 218                 entry = entry->next;
 219         }
 220
 221         if (check_compaction(mem_free, hugepage_size) == 0)
 222                 return 0;
 223
 224         return -1;
 225 }