1 // SPDX-License-Identifier: GPL-2.0
2 /* Test selecting other page sizes for mmap/shmget.
4 Before running this huge pages for each huge page size must have been
6 For large pages beyond MAX_ORDER (like 1GB on x86) boot options must be used.
7 Also shmmax must be increased.
8 And you need to run as root to work around some weird permissions in shm.
9 And nothing using huge pages should run in parallel.
10 When the program aborts you may need to clean up the shm segments with
11 ipcrm -m by hand, like this
12 sudo ipcs | awk '$1 == "0x00000000" {print $2}' | xargs -n1 sudo ipcrm -m
13 (warning this will remove all if someone else uses them) */
28 #define err(x) perror(x), exit(1)
30 #define MAP_HUGE_2MB (21 << MAP_HUGE_SHIFT)
31 #define MAP_HUGE_1GB (30 << MAP_HUGE_SHIFT)
32 #define MAP_HUGE_SHIFT 26
33 #define MAP_HUGE_MASK 0x3f
34 #if !defined(MAP_HUGETLB)
35 #define MAP_HUGETLB 0x40000
38 #define SHM_HUGETLB 04000 /* segment will use huge TLB pages */
39 #define SHM_HUGE_SHIFT 26
40 #define SHM_HUGE_MASK 0x3f
41 #define SHM_HUGE_2MB (21 << SHM_HUGE_SHIFT)
42 #define SHM_HUGE_1GB (30 << SHM_HUGE_SHIFT)
44 #define NUM_PAGESIZES 5
48 #define Dprintf(fmt...) // printf(fmt)
50 unsigned long page_sizes[NUM_PAGESIZES];
53 int ilog2(unsigned long v)
56 while ((1UL << l) < v)
61 void find_pagesizes(void)
65 glob("/sys/kernel/mm/hugepages/hugepages-*kB", 0, NULL, &g);
66 assert(g.gl_pathc <= NUM_PAGESIZES);
67 for (i = 0; i < g.gl_pathc; i++) {
68 sscanf(g.gl_pathv[i], "/sys/kernel/mm/hugepages/hugepages-%lukB",
71 printf("Found %luMB\n", page_sizes[i] >> 20);
73 num_page_sizes = g.gl_pathc;
77 unsigned long default_huge_page_size(void)
79 unsigned long hps = 0;
82 FILE *f = fopen("/proc/meminfo", "r");
85 while (getline(&line, &linelen, f) > 0) {
86 if (sscanf(line, "Hugepagesize: %lu kB", &hps) == 1) {
95 void show(unsigned long ps)
98 if (ps == getpagesize())
100 printf("%luMB: ", ps >> 20);
102 snprintf(buf, sizeof buf,
103 "cat /sys/kernel/mm/hugepages/hugepages-%lukB/free_hugepages",
108 unsigned long read_sysfs(int warn, char *fmt, ...)
115 unsigned long val = 0;
118 vsnprintf(buf, sizeof buf, fmt, ap);
124 printf("missing %s\n", buf);
127 if (getline(&line, &linelen, f) > 0) {
128 sscanf(line, "%lu", &val);
135 unsigned long read_free(unsigned long ps)
137 return read_sysfs(ps != getpagesize(),
138 "/sys/kernel/mm/hugepages/hugepages-%lukB/free_hugepages",
142 void test_mmap(unsigned long size, unsigned flags)
145 unsigned long before, after;
148 before = read_free(size);
149 map = mmap(NULL, size*NUM_PAGES, PROT_READ|PROT_WRITE,
150 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB|flags, -1, 0);
152 if (map == (char *)-1) err("mmap");
153 memset(map, 0xff, size*NUM_PAGES);
154 after = read_free(size);
155 Dprintf("before %lu after %lu diff %ld size %lu\n",
156 before, after, before - after, size);
157 assert(size == getpagesize() || (before - after) == NUM_PAGES);
159 err = munmap(map, size);
163 void test_shmget(unsigned long size, unsigned flags)
166 unsigned long before, after;
169 before = read_free(size);
170 id = shmget(IPC_PRIVATE, size * NUM_PAGES, IPC_CREAT|0600|flags);
171 if (id < 0) err("shmget");
174 if (shmctl(id, SHM_INFO, (void *)&i) < 0) err("shmctl");
175 Dprintf("alloc %lu res %lu\n", i.shm_tot, i.shm_rss);
178 Dprintf("id %d\n", id);
179 char *map = shmat(id, NULL, 0600);
180 if (map == (char*)-1) err("shmat");
182 shmctl(id, IPC_RMID, NULL);
184 memset(map, 0xff, size*NUM_PAGES);
185 after = read_free(size);
187 Dprintf("before %lu after %lu diff %ld size %lu\n",
188 before, after, before - after, size);
189 assert(size == getpagesize() || (before - after) == NUM_PAGES);
195 void sanity_checks(void)
198 unsigned long largest = getpagesize();
200 for (i = 0; i < num_page_sizes; i++) {
201 if (page_sizes[i] > largest)
202 largest = page_sizes[i];
204 if (read_free(page_sizes[i]) < NUM_PAGES) {
205 printf("Not enough huge pages for page size %lu MB, need %u\n",
212 if (read_sysfs(0, "/proc/sys/kernel/shmmax") < NUM_PAGES * largest) {
213 printf("Please do echo %lu > /proc/sys/kernel/shmmax", largest * NUM_PAGES);
217 #if defined(__x86_64__)
218 if (largest != 1U<<30) {
219 printf("No GB pages available on x86-64\n"
220 "Please boot with hugepagesz=1G hugepages=%d\n", NUM_PAGES);
229 unsigned default_hps = default_huge_page_size();
235 for (i = 0; i < num_page_sizes; i++) {
236 unsigned long ps = page_sizes[i];
237 int arg = ilog2(ps) << MAP_HUGE_SHIFT;
238 printf("Testing %luMB mmap with shift %x\n", ps >> 20, arg);
239 test_mmap(ps, MAP_HUGETLB | arg);
241 printf("Testing default huge mmap\n");
242 test_mmap(default_hps, SHM_HUGETLB);
244 puts("Testing non-huge shmget");
245 test_shmget(getpagesize(), 0);
247 for (i = 0; i < num_page_sizes; i++) {
248 unsigned long ps = page_sizes[i];
249 int arg = ilog2(ps) << SHM_HUGE_SHIFT;
250 printf("Testing %luMB shmget with shift %x\n", ps >> 20, arg);
251 test_shmget(ps, SHM_HUGETLB | arg);
253 puts("default huge shmget");
254 test_shmget(default_hps, SHM_HUGETLB);