tools/testing/selftests/vm/compaction_test.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *
   4  * A test for the patch "Allow compaction of unevictable pages".
   5  * With this patch we should be able to allocate at least 1/4
   6  * of RAM in huge pages. Without the patch much less is
   7  * allocated.
   8  */
   9
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <sys/mman.h>
  13 #include <sys/resource.h>
  14 #include <fcntl.h>
  15 #include <errno.h>
  16 #include <unistd.h>
  17 #include <string.h>
  18
  19 #define MAP_SIZE 1048576
  20
  21 struct map_list {
  22         void *map;
  23         struct map_list *next;
  24 };
  25
  26 int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
  27 {
  28         char  buffer[256] = {0};
  29         char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
  30         FILE *cmdfile = popen(cmd, "r");
  31
  32         if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
  33                 perror("Failed to read meminfo\n");
  34                 return -1;
  35         }
  36
  37         pclose(cmdfile);
  38
  39         *memfree = atoll(buffer);
  40         cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
  41         cmdfile = popen(cmd, "r");
  42
  43         if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
  44                 perror("Failed to read meminfo\n");
  45                 return -1;
  46         }
  47
  48         pclose(cmdfile);
  49         *hugepagesize = atoll(buffer);
  50
  51         return 0;
  52 }
  53
  54 int prereq(void)
  55 {
  56         char allowed;
  57         int fd;
  58
  59         fd = open("/proc/sys/vm/compact_unevictable_allowed",
  60                   O_RDONLY | O_NONBLOCK);
  61         if (fd < 0) {
  62                 perror("Failed to open\n"
  63                        "/proc/sys/vm/compact_unevictable_allowed\n");
  64                 return -1;
  65         }
  66
  67         if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
  68                 perror("Failed to read from\n"
  69                        "/proc/sys/vm/compact_unevictable_allowed\n");
  70                 close(fd);
  71                 return -1;
  72         }
  73
  74         close(fd);
  75         if (allowed == '1')
  76                 return 0;
  77
  78         return -1;
  79 }
  80
  81 int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
  82 {
  83         int fd;
  84         int compaction_index = 0;
  85         char initial_nr_hugepages[10] = {0};
  86         char nr_hugepages[10] = {0};
  87
  88         /* We want to test with 80% of available memory. Else, OOM killer comes
  89            in to play */
  90         mem_free = mem_free * 0.8;
  91
  92         fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
  93         if (fd < 0) {
  94                 perror("Failed to open /proc/sys/vm/nr_hugepages");
  95                 return -1;
  96         }
  97
  98         if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) {
  99                 perror("Failed to read from /proc/sys/vm/nr_hugepages");
 100                 goto close_fd;
 101         }
 102
 103         /* Start with the initial condition of 0 huge pages*/
 104         if (write(fd, "0", sizeof(char)) != sizeof(char)) {
 105                 perror("Failed to write 0 to /proc/sys/vm/nr_hugepages\n");
 106                 goto close_fd;
 107         }
 108
 109         lseek(fd, 0, SEEK_SET);
 110
 111         /* Request a large number of huge pages. The Kernel will allocate
 112            as much as it can */
 113         if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
 114                 perror("Failed to write 100000 to /proc/sys/vm/nr_hugepages\n");
 115                 goto close_fd;
 116         }
 117
 118         lseek(fd, 0, SEEK_SET);
 119
 120         if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
 121                 perror("Failed to re-read from /proc/sys/vm/nr_hugepages\n");
 122                 goto close_fd;
 123         }
 124
 125         /* We should have been able to request at least 1/3 rd of the memory in
 126            huge pages */
 127         compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
 128
 129         if (compaction_index > 3) {
 130                 printf("No of huge pages allocated = %d\n",
 131                        (atoi(nr_hugepages)));
 132                 fprintf(stderr, "ERROR: Less that 1/%d of memory is available\n"
 133                         "as huge pages\n", compaction_index);
 134                 goto close_fd;
 135         }
 136
 137         printf("No of huge pages allocated = %d\n",
 138                (atoi(nr_hugepages)));
 139
 140         lseek(fd, 0, SEEK_SET);
 141
 142         if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
 143             != strlen(initial_nr_hugepages)) {
 144                 perror("Failed to write value to /proc/sys/vm/nr_hugepages\n");
 145                 goto close_fd;
 146         }
 147
 148         close(fd);
 149         return 0;
 150
 151  close_fd:
 152         close(fd);
 153         printf("Not OK. Compaction test failed.");
 154         return -1;
 155 }
 156
 157
 158 int main(int argc, char **argv)
 159 {
 160         struct rlimit lim;
 161         struct map_list *list, *entry;
 162         size_t page_size, i;
 163         void *map = NULL;
 164         unsigned long mem_free = 0;
 165         unsigned long hugepage_size = 0;
 166         unsigned long mem_fragmentable = 0;
 167
 168         if (prereq() != 0) {
 169                 printf("Either the sysctl compact_unevictable_allowed is not\n"
 170                        "set to 1 or couldn't read the proc file.\n"
 171                        "Skipping the test\n");
 172                 return 0;
 173         }
 174
 175         lim.rlim_cur = RLIM_INFINITY;
 176         lim.rlim_max = RLIM_INFINITY;
 177         if (setrlimit(RLIMIT_MEMLOCK, &lim)) {
 178                 perror("Failed to set rlimit:\n");
 179                 return -1;
 180         }
 181
 182         page_size = getpagesize();
 183
 184         list = NULL;
 185
 186         if (read_memory_info(&mem_free, &hugepage_size) != 0) {
 187                 printf("ERROR: Cannot read meminfo\n");
 188                 return -1;
 189         }
 190
 191         mem_fragmentable = mem_free * 0.8 / 1024;
 192
 193         while (mem_fragmentable > 0) {
 194                 map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
 195                            MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
 196                 if (map == MAP_FAILED)
 197                         break;
 198
 199                 entry = malloc(sizeof(struct map_list));
 200                 if (!entry) {
 201                         munmap(map, MAP_SIZE);
 202                         break;
 203                 }
 204                 entry->map = map;
 205                 entry->next = list;
 206                 list = entry;
 207
 208                 /* Write something (in this case the address of the map) to
 209                  * ensure that KSM can't merge the mapped pages
 210                  */
 211                 for (i = 0; i < MAP_SIZE; i += page_size)
 212                         *(unsigned long *)(map + i) = (unsigned long)map + i;
 213
 214                 mem_fragmentable--;
 215         }
 216
 217         for (entry = list; entry != NULL; entry = entry->next) {
 218                 munmap(entry->map, MAP_SIZE);
 219                 if (!entry->next)
 220                         break;
 221                 entry = entry->next;
 222         }
 223
 224         if (check_compaction(mem_free, hugepage_size) == 0)
 225                 return 0;
 226
 227         return -1;
 228 }