tools/testing/selftests/mm/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 #include "../kselftest.h"
  20
  21 #define MAP_SIZE_MB     100
  22 #define MAP_SIZE        (MAP_SIZE_MB * 1024 * 1024)
  23
  24 struct map_list {
  25         void *map;
  26         struct map_list *next;
  27 };
  28
  29 int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
  30 {
  31         char  buffer[256] = {0};
  32         char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
  33         FILE *cmdfile = popen(cmd, "r");
  34
  35         if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
  36                 perror("Failed to read meminfo\n");
  37                 return -1;
  38         }
  39
  40         pclose(cmdfile);
  41
  42         *memfree = atoll(buffer);
  43         cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
  44         cmdfile = popen(cmd, "r");
  45
  46         if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
  47                 perror("Failed to read meminfo\n");
  48                 return -1;
  49         }
  50
  51         pclose(cmdfile);
  52         *hugepagesize = atoll(buffer);
  53
  54         return 0;
  55 }
  56
  57 int prereq(void)
  58 {
  59         char allowed;
  60         int fd;
  61
  62         fd = open("/proc/sys/vm/compact_unevictable_allowed",
  63                   O_RDONLY | O_NONBLOCK);
  64         if (fd < 0) {
  65                 perror("Failed to open\n"
  66                        "/proc/sys/vm/compact_unevictable_allowed\n");
  67                 return -1;
  68         }
  69
  70         if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
  71                 perror("Failed to read from\n"
  72                        "/proc/sys/vm/compact_unevictable_allowed\n");
  73                 close(fd);
  74                 return -1;
  75         }
  76
  77         close(fd);
  78         if (allowed == '1')
  79                 return 0;
  80
  81         return -1;
  82 }
  83
  84 int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
  85 {
  86         int fd;
  87         int compaction_index = 0;
  88         char initial_nr_hugepages[10] = {0};
  89         char nr_hugepages[10] = {0};
  90
  91         /* We want to test with 80% of available memory. Else, OOM killer comes
  92            in to play */
  93         mem_free = mem_free * 0.8;
  94
  95         fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
  96         if (fd < 0) {
  97                 perror("Failed to open /proc/sys/vm/nr_hugepages");
  98                 return -1;
  99         }
 100
 101         if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) {
 102                 perror("Failed to read from /proc/sys/vm/nr_hugepages");
 103                 goto close_fd;
 104         }
 105
 106         /* Start with the initial condition of 0 huge pages*/
 107         if (write(fd, "0", sizeof(char)) != sizeof(char)) {
 108                 perror("Failed to write 0 to /proc/sys/vm/nr_hugepages\n");
 109                 goto close_fd;
 110         }
 111
 112         lseek(fd, 0, SEEK_SET);
 113
 114         /* Request a large number of huge pages. The Kernel will allocate
 115            as much as it can */
 116         if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
 117                 perror("Failed to write 100000 to /proc/sys/vm/nr_hugepages\n");
 118                 goto close_fd;
 119         }
 120
 121         lseek(fd, 0, SEEK_SET);
 122
 123         if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
 124                 perror("Failed to re-read from /proc/sys/vm/nr_hugepages\n");
 125                 goto close_fd;
 126         }
 127
 128         /* We should have been able to request at least 1/3 rd of the memory in
 129            huge pages */
 130         compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
 131
 132         if (compaction_index > 3) {
 133                 printf("No of huge pages allocated = %d\n",
 134                        (atoi(nr_hugepages)));
 135                 fprintf(stderr, "ERROR: Less that 1/%d of memory is available\n"
 136                         "as huge pages\n", compaction_index);
 137                 goto close_fd;
 138         }
 139
 140         printf("No of huge pages allocated = %d\n",
 141                (atoi(nr_hugepages)));
 142
 143         lseek(fd, 0, SEEK_SET);
 144
 145         if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
 146             != strlen(initial_nr_hugepages)) {
 147                 perror("Failed to write value to /proc/sys/vm/nr_hugepages\n");
 148                 goto close_fd;
 149         }
 150
 151         close(fd);
 152         return 0;
 153
 154  close_fd:
 155         close(fd);
 156         printf("Not OK. Compaction test failed.");
 157         return -1;
 158 }
 159
 160
 161 int main(int argc, char **argv)
 162 {
 163         struct rlimit lim;
 164         struct map_list *list, *entry;
 165         size_t page_size, i;
 166         void *map = NULL;
 167         unsigned long mem_free = 0;
 168         unsigned long hugepage_size = 0;
 169         long mem_fragmentable_MB = 0;
 170
 171         if (prereq() != 0) {
 172                 printf("Either the sysctl compact_unevictable_allowed is not\n"
 173                        "set to 1 or couldn't read the proc file.\n"
 174                        "Skipping the test\n");
 175                 return KSFT_SKIP;
 176         }
 177
 178         lim.rlim_cur = RLIM_INFINITY;
 179         lim.rlim_max = RLIM_INFINITY;
 180         if (setrlimit(RLIMIT_MEMLOCK, &lim)) {
 181                 perror("Failed to set rlimit:\n");
 182                 return -1;
 183         }
 184
 185         page_size = getpagesize();
 186
 187         list = NULL;
 188
 189         if (read_memory_info(&mem_free, &hugepage_size) != 0) {
 190                 printf("ERROR: Cannot read meminfo\n");
 191                 return -1;
 192         }
 193
 194         mem_fragmentable_MB = mem_free * 0.8 / 1024;
 195
 196         while (mem_fragmentable_MB > 0) {
 197                 map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
 198                            MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
 199                 if (map == MAP_FAILED)
 200                         break;
 201
 202                 entry = malloc(sizeof(struct map_list));
 203                 if (!entry) {
 204                         munmap(map, MAP_SIZE);
 205                         break;
 206                 }
 207                 entry->map = map;
 208                 entry->next = list;
 209                 list = entry;
 210
 211                 /* Write something (in this case the address of the map) to
 212                  * ensure that KSM can't merge the mapped pages
 213                  */
 214                 for (i = 0; i < MAP_SIZE; i += page_size)
 215                         *(unsigned long *)(map + i) = (unsigned long)map + i;
 216
 217                 mem_fragmentable_MB -= MAP_SIZE_MB;
 218         }
 219
 220         for (entry = list; entry != NULL; entry = entry->next) {
 221                 munmap(entry->map, MAP_SIZE);
 222                 if (!entry->next)
 223                         break;
 224                 entry = entry->next;
 225         }
 226
 227         if (check_compaction(mem_free, hugepage_size) == 0)
 228                 return 0;
 229
 230         return -1;
 231 }