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         if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
 141             != strlen(initial_nr_hugepages)) {
 142                 perror("Failed to write value to /proc/sys/vm/nr_hugepages\n");
 143                 goto close_fd;
 144         }
 145
 146         close(fd);
 147         return 0;
 148
 149  close_fd:
 150         close(fd);
 151         printf("Not OK. Compaction test failed.");
 152         return -1;
 153 }
 154
 155
 156 int main(int argc, char **argv)
 157 {
 158         struct rlimit lim;
 159         struct map_list *list, *entry;
 160         size_t page_size, i;
 161         void *map = NULL;
 162         unsigned long mem_free = 0;
 163         unsigned long hugepage_size = 0;
 164         unsigned long mem_fragmentable = 0;
 165
 166         if (prereq() != 0) {
 167                 printf("Either the sysctl compact_unevictable_allowed is not\n"
 168                        "set to 1 or couldn't read the proc file.\n"
 169                        "Skipping the test\n");
 170                 return 0;
 171         }
 172
 173         lim.rlim_cur = RLIM_INFINITY;
 174         lim.rlim_max = RLIM_INFINITY;
 175         if (setrlimit(RLIMIT_MEMLOCK, &lim)) {
 176                 perror("Failed to set rlimit:\n");
 177                 return -1;
 178         }
 179
 180         page_size = getpagesize();
 181
 182         list = NULL;
 183
 184         if (read_memory_info(&mem_free, &hugepage_size) != 0) {
 185                 printf("ERROR: Cannot read meminfo\n");
 186                 return -1;
 187         }
 188
 189         mem_fragmentable = mem_free * 0.8 / 1024;
 190
 191         while (mem_fragmentable > 0) {
 192                 map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
 193                            MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
 194                 if (map == MAP_FAILED)
 195                         break;
 196
 197                 entry = malloc(sizeof(struct map_list));
 198                 if (!entry) {
 199                         munmap(map, MAP_SIZE);
 200                         break;
 201                 }
 202                 entry->map = map;
 203                 entry->next = list;
 204                 list = entry;
 205
 206                 /* Write something (in this case the address of the map) to
 207                  * ensure that KSM can't merge the mapped pages
 208                  */
 209                 for (i = 0; i < MAP_SIZE; i += page_size)
 210                         *(unsigned long *)(map + i) = (unsigned long)map + i;
 211
 212                 mem_fragmentable--;
 213         }
 214
 215         for (entry = list; entry != NULL; entry = entry->next) {
 216                 munmap(entry->map, MAP_SIZE);
 217                 if (!entry->next)
 218                         break;
 219                 entry = entry->next;
 220         }
 221
 222         if (check_compaction(mem_free, hugepage_size) == 0)
 223                 return 0;
 224
 225         return -1;
 226 }