1 /* Test selecting other page sizes for mmap/shmget. 2 3 Before running this huge pages for each huge page size must have been 4 reserved. 5 For large pages beyond MAX_ORDER (like 1GB on x86) boot options must be used. 6 Also shmmax must be increased. 7 And you need to run as root to work around some weird permissions in shm. 8 And nothing using huge pages should run in parallel. 9 When the program aborts you may need to clean up the shm segments with 10 ipcrm -m by hand, like this 11 sudo ipcs | awk '$1 == "0x00000000" {print $2}' | xargs -n1 sudo ipcrm -m 12 (warning this will remove all if someone else uses them) */ 13 14 #define _GNU_SOURCE 1 15 #include <sys/mman.h> 16 #include <stdlib.h> 17 #include <stdio.h> 18 #include <sys/ipc.h> 19 #include <sys/shm.h> 20 #include <sys/stat.h> 21 #include <glob.h> 22 #include <assert.h> 23 #include <unistd.h> 24 #include <stdarg.h> 25 #include <string.h> 26 27 #define err(x) perror(x), exit(1) 28 29 #define MAP_HUGE_2MB (21 << MAP_HUGE_SHIFT) 30 #define MAP_HUGE_1GB (30 << MAP_HUGE_SHIFT) 31 #define MAP_HUGE_SHIFT 26 32 #define MAP_HUGE_MASK 0x3f 33 #if !defined(MAP_HUGETLB) 34 #define MAP_HUGETLB 0x40000 35 #endif 36 37 #define SHM_HUGETLB 04000 /* segment will use huge TLB pages */ 38 #define SHM_HUGE_SHIFT 26 39 #define SHM_HUGE_MASK 0x3f 40 #define SHM_HUGE_2MB (21 << SHM_HUGE_SHIFT) 41 #define SHM_HUGE_1GB (30 << SHM_HUGE_SHIFT) 42 43 #define NUM_PAGESIZES 5 44 45 #define NUM_PAGES 4 46 47 #define Dprintf(fmt...) // printf(fmt) 48 49 unsigned long page_sizes[NUM_PAGESIZES]; 50 int num_page_sizes; 51 52 int ilog2(unsigned long v) 53 { 54 int l = 0; 55 while ((1UL << l) < v) 56 l++; 57 return l; 58 } 59 60 void find_pagesizes(void) 61 { 62 glob_t g; 63 int i; 64 glob("/sys/kernel/mm/hugepages/hugepages-*kB", 0, NULL, &g); 65 assert(g.gl_pathc <= NUM_PAGESIZES); 66 for (i = 0; i < g.gl_pathc; i++) { 67 sscanf(g.gl_pathv[i], "/sys/kernel/mm/hugepages/hugepages-%lukB", 68 &page_sizes[i]); 69 page_sizes[i] <<= 10; 70 printf("Found %luMB\n", page_sizes[i] >> 20); 71 } 72 num_page_sizes = g.gl_pathc; 73 globfree(&g); 74 } 75 76 unsigned long default_huge_page_size(void) 77 { 78 unsigned long hps = 0; 79 char *line = NULL; 80 size_t linelen = 0; 81 FILE *f = fopen("/proc/meminfo", "r"); 82 if (!f) 83 return 0; 84 while (getline(&line, &linelen, f) > 0) { 85 if (sscanf(line, "Hugepagesize: %lu kB", &hps) == 1) { 86 hps <<= 10; 87 break; 88 } 89 } 90 free(line); 91 return hps; 92 } 93 94 void show(unsigned long ps) 95 { 96 char buf[100]; 97 if (ps == getpagesize()) 98 return; 99 printf("%luMB: ", ps >> 20); 100 fflush(stdout); 101 snprintf(buf, sizeof buf, 102 "cat /sys/kernel/mm/hugepages/hugepages-%lukB/free_hugepages", 103 ps >> 10); 104 system(buf); 105 } 106 107 unsigned long read_sysfs(int warn, char *fmt, ...) 108 { 109 char *line = NULL; 110 size_t linelen = 0; 111 char buf[100]; 112 FILE *f; 113 va_list ap; 114 unsigned long val = 0; 115 116 va_start(ap, fmt); 117 vsnprintf(buf, sizeof buf, fmt, ap); 118 va_end(ap); 119 120 f = fopen(buf, "r"); 121 if (!f) { 122 if (warn) 123 printf("missing %s\n", buf); 124 return 0; 125 } 126 if (getline(&line, &linelen, f) > 0) { 127 sscanf(line, "%lu", &val); 128 } 129 fclose(f); 130 free(line); 131 return val; 132 } 133 134 unsigned long read_free(unsigned long ps) 135 { 136 return read_sysfs(ps != getpagesize(), 137 "/sys/kernel/mm/hugepages/hugepages-%lukB/free_hugepages", 138 ps >> 10); 139 } 140 141 void test_mmap(unsigned long size, unsigned flags) 142 { 143 char *map; 144 unsigned long before, after; 145 int err; 146 147 before = read_free(size); 148 map = mmap(NULL, size*NUM_PAGES, PROT_READ|PROT_WRITE, 149 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB|flags, 0, 0); 150 151 if (map == (char *)-1) err("mmap"); 152 memset(map, 0xff, size*NUM_PAGES); 153 after = read_free(size); 154 Dprintf("before %lu after %lu diff %ld size %lu\n", 155 before, after, before - after, size); 156 assert(size == getpagesize() || (before - after) == NUM_PAGES); 157 show(size); 158 err = munmap(map, size); 159 assert(!err); 160 } 161 162 void test_shmget(unsigned long size, unsigned flags) 163 { 164 int id; 165 unsigned long before, after; 166 int err; 167 168 before = read_free(size); 169 id = shmget(IPC_PRIVATE, size * NUM_PAGES, IPC_CREAT|0600|flags); 170 if (id < 0) err("shmget"); 171 172 struct shm_info i; 173 if (shmctl(id, SHM_INFO, (void *)&i) < 0) err("shmctl"); 174 Dprintf("alloc %lu res %lu\n", i.shm_tot, i.shm_rss); 175 176 177 Dprintf("id %d\n", id); 178 char *map = shmat(id, NULL, 0600); 179 if (map == (char*)-1) err("shmat"); 180 181 shmctl(id, IPC_RMID, NULL); 182 183 memset(map, 0xff, size*NUM_PAGES); 184 after = read_free(size); 185 186 Dprintf("before %lu after %lu diff %ld size %lu\n", 187 before, after, before - after, size); 188 assert(size == getpagesize() || (before - after) == NUM_PAGES); 189 show(size); 190 err = shmdt(map); 191 assert(!err); 192 } 193 194 void sanity_checks(void) 195 { 196 int i; 197 unsigned long largest = getpagesize(); 198 199 for (i = 0; i < num_page_sizes; i++) { 200 if (page_sizes[i] > largest) 201 largest = page_sizes[i]; 202 203 if (read_free(page_sizes[i]) < NUM_PAGES) { 204 printf("Not enough huge pages for page size %lu MB, need %u\n", 205 page_sizes[i] >> 20, 206 NUM_PAGES); 207 exit(0); 208 } 209 } 210 211 if (read_sysfs(0, "/proc/sys/kernel/shmmax") < NUM_PAGES * largest) { 212 printf("Please do echo %lu > /proc/sys/kernel/shmmax", largest * NUM_PAGES); 213 exit(0); 214 } 215 216 #if defined(__x86_64__) 217 if (largest != 1U<<30) { 218 printf("No GB pages available on x86-64\n" 219 "Please boot with hugepagesz=1G hugepages=%d\n", NUM_PAGES); 220 exit(0); 221 } 222 #endif 223 } 224 225 int main(void) 226 { 227 int i; 228 unsigned default_hps = default_huge_page_size(); 229 230 find_pagesizes(); 231 232 sanity_checks(); 233 234 for (i = 0; i < num_page_sizes; i++) { 235 unsigned long ps = page_sizes[i]; 236 int arg = ilog2(ps) << MAP_HUGE_SHIFT; 237 printf("Testing %luMB mmap with shift %x\n", ps >> 20, arg); 238 test_mmap(ps, MAP_HUGETLB | arg); 239 } 240 printf("Testing default huge mmap\n"); 241 test_mmap(default_hps, SHM_HUGETLB); 242 243 puts("Testing non-huge shmget"); 244 test_shmget(getpagesize(), 0); 245 246 for (i = 0; i < num_page_sizes; i++) { 247 unsigned long ps = page_sizes[i]; 248 int arg = ilog2(ps) << SHM_HUGE_SHIFT; 249 printf("Testing %luMB shmget with shift %x\n", ps >> 20, arg); 250 test_shmget(ps, SHM_HUGETLB | arg); 251 } 252 puts("default huge shmget"); 253 test_shmget(default_hps, SHM_HUGETLB); 254 255 return 0; 256 } 257
