// SPDX-License-Identifier: GPL-2.0
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/* Test selecting other page sizes for mmap/shmget.
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Before running this huge pages for each huge page size must have been
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reserved.
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For large pages beyond MAX_ORDER (like 1GB on x86) boot options must be used.
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Also shmmax must be increased.
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And you need to run as root to work around some weird permissions in shm.
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And nothing using huge pages should run in parallel.
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When the program aborts you may need to clean up the shm segments with
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ipcrm -m by hand, like this
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sudo ipcs | awk '$1 == "0x00000000" {print $2}' | xargs -n1 sudo ipcrm -m
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(warning this will remove all if someone else uses them) */
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#define _GNU_SOURCE 1
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#include <sys/mman.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <sys/ipc.h>
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#include <sys/shm.h>
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#include <sys/stat.h>
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#include <glob.h>
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#include <assert.h>
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#include <unistd.h>
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#include <stdarg.h>
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#include <string.h>
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#define err(x) perror(x), exit(1)
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#define MAP_HUGE_2MB (21 << MAP_HUGE_SHIFT)
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#define MAP_HUGE_1GB (30 << MAP_HUGE_SHIFT)
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#define MAP_HUGE_SHIFT 26
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#define MAP_HUGE_MASK 0x3f
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#if !defined(MAP_HUGETLB)
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#define MAP_HUGETLB 0x40000
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#endif
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#define SHM_HUGETLB 04000 /* segment will use huge TLB pages */
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#define SHM_HUGE_SHIFT 26
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#define SHM_HUGE_MASK 0x3f
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#define SHM_HUGE_2MB (21 << SHM_HUGE_SHIFT)
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#define SHM_HUGE_1GB (30 << SHM_HUGE_SHIFT)
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#define NUM_PAGESIZES 5
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#define NUM_PAGES 4
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#define Dprintf(fmt...) // printf(fmt)
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unsigned long page_sizes[NUM_PAGESIZES];
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int num_page_sizes;
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int ilog2(unsigned long v)
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{
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int l = 0;
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while ((1UL << l) < v)
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l++;
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return l;
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}
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void find_pagesizes(void)
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{
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glob_t g;
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int i;
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glob("/sys/kernel/mm/hugepages/hugepages-*kB", 0, NULL, &g);
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assert(g.gl_pathc <= NUM_PAGESIZES);
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for (i = 0; i < g.gl_pathc; i++) {
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sscanf(g.gl_pathv[i], "/sys/kernel/mm/hugepages/hugepages-%lukB",
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&page_sizes[i]);
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page_sizes[i] <<= 10;
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printf("Found %luMB\n", page_sizes[i] >> 20);
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}
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num_page_sizes = g.gl_pathc;
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globfree(&g);
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}
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unsigned long default_huge_page_size(void)
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{
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unsigned long hps = 0;
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char *line = NULL;
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size_t linelen = 0;
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FILE *f = fopen("/proc/meminfo", "r");
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if (!f)
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return 0;
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while (getline(&line, &linelen, f) > 0) {
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if (sscanf(line, "Hugepagesize: %lu kB", &hps) == 1) {
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hps <<= 10;
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break;
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}
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}
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free(line);
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return hps;
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}
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void show(unsigned long ps)
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{
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char buf[100];
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if (ps == getpagesize())
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return;
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printf("%luMB: ", ps >> 20);
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fflush(stdout);
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snprintf(buf, sizeof buf,
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"cat /sys/kernel/mm/hugepages/hugepages-%lukB/free_hugepages",
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ps >> 10);
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system(buf);
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}
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unsigned long read_sysfs(int warn, char *fmt, ...)
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{
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char *line = NULL;
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size_t linelen = 0;
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char buf[100];
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FILE *f;
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va_list ap;
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unsigned long val = 0;
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va_start(ap, fmt);
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vsnprintf(buf, sizeof buf, fmt, ap);
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va_end(ap);
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f = fopen(buf, "r");
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if (!f) {
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if (warn)
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printf("missing %s\n", buf);
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return 0;
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}
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if (getline(&line, &linelen, f) > 0) {
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sscanf(line, "%lu", &val);
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}
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fclose(f);
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free(line);
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return val;
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}
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unsigned long read_free(unsigned long ps)
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{
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return read_sysfs(ps != getpagesize(),
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"/sys/kernel/mm/hugepages/hugepages-%lukB/free_hugepages",
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ps >> 10);
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}
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void test_mmap(unsigned long size, unsigned flags)
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{
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char *map;
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unsigned long before, after;
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int err;
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before = read_free(size);
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map = mmap(NULL, size*NUM_PAGES, PROT_READ|PROT_WRITE,
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MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB|flags, -1, 0);
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if (map == (char *)-1) err("mmap");
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memset(map, 0xff, size*NUM_PAGES);
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after = read_free(size);
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Dprintf("before %lu after %lu diff %ld size %lu\n",
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before, after, before - after, size);
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assert(size == getpagesize() || (before - after) == NUM_PAGES);
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show(size);
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err = munmap(map, size);
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assert(!err);
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}
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void test_shmget(unsigned long size, unsigned flags)
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{
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int id;
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unsigned long before, after;
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int err;
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before = read_free(size);
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id = shmget(IPC_PRIVATE, size * NUM_PAGES, IPC_CREAT|0600|flags);
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if (id < 0) err("shmget");
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struct shm_info i;
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if (shmctl(id, SHM_INFO, (void *)&i) < 0) err("shmctl");
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Dprintf("alloc %lu res %lu\n", i.shm_tot, i.shm_rss);
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Dprintf("id %d\n", id);
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char *map = shmat(id, NULL, 0600);
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if (map == (char*)-1) err("shmat");
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shmctl(id, IPC_RMID, NULL);
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memset(map, 0xff, size*NUM_PAGES);
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after = read_free(size);
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Dprintf("before %lu after %lu diff %ld size %lu\n",
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before, after, before - after, size);
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assert(size == getpagesize() || (before - after) == NUM_PAGES);
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show(size);
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err = shmdt(map);
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assert(!err);
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}
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void sanity_checks(void)
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{
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int i;
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unsigned long largest = getpagesize();
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for (i = 0; i < num_page_sizes; i++) {
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if (page_sizes[i] > largest)
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largest = page_sizes[i];
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if (read_free(page_sizes[i]) < NUM_PAGES) {
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printf("Not enough huge pages for page size %lu MB, need %u\n",
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page_sizes[i] >> 20,
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NUM_PAGES);
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exit(0);
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}
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}
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if (read_sysfs(0, "/proc/sys/kernel/shmmax") < NUM_PAGES * largest) {
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printf("Please do echo %lu > /proc/sys/kernel/shmmax", largest * NUM_PAGES);
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exit(0);
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}
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#if defined(__x86_64__)
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if (largest != 1U<<30) {
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printf("No GB pages available on x86-64\n"
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"Please boot with hugepagesz=1G hugepages=%d\n", NUM_PAGES);
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exit(0);
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}
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#endif
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}
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int main(void)
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{
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int i;
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unsigned default_hps = default_huge_page_size();
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find_pagesizes();
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sanity_checks();
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for (i = 0; i < num_page_sizes; i++) {
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unsigned long ps = page_sizes[i];
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int arg = ilog2(ps) << MAP_HUGE_SHIFT;
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printf("Testing %luMB mmap with shift %x\n", ps >> 20, arg);
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test_mmap(ps, MAP_HUGETLB | arg);
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}
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printf("Testing default huge mmap\n");
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test_mmap(default_hps, SHM_HUGETLB);
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puts("Testing non-huge shmget");
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test_shmget(getpagesize(), 0);
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for (i = 0; i < num_page_sizes; i++) {
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unsigned long ps = page_sizes[i];
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int arg = ilog2(ps) << SHM_HUGE_SHIFT;
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printf("Testing %luMB shmget with shift %x\n", ps >> 20, arg);
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test_shmget(ps, SHM_HUGETLB | arg);
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}
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puts("default huge shmget");
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test_shmget(default_hps, SHM_HUGETLB);
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return 0;
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}
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