root/tools/testing/selftests/mm/ksm_tests.c
// SPDX-License-Identifier: GPL-2.0

#include <sys/mman.h>
#include <sys/prctl.h>
#include <sys/wait.h>
#include <stdbool.h>
#include <time.h>
#include <string.h>
#include <numa.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdint.h>
#include <err.h>

#include "kselftest.h"
#include <include/vdso/time64.h>
#include "vm_util.h"
#include "thp_settings.h"

#define KSM_SYSFS_PATH "/sys/kernel/mm/ksm/"
#define KSM_FP(s) (KSM_SYSFS_PATH s)
#define KSM_SCAN_LIMIT_SEC_DEFAULT 120
#define KSM_PAGE_COUNT_DEFAULT 10l
#define KSM_PROT_STR_DEFAULT "rw"
#define KSM_USE_ZERO_PAGES_DEFAULT false
#define KSM_MERGE_ACROSS_NODES_DEFAULT true
#define KSM_MERGE_TYPE_DEFAULT 0
#define MB (1ul << 20)

struct ksm_sysfs {
        unsigned long max_page_sharing;
        unsigned long merge_across_nodes;
        unsigned long pages_to_scan;
        unsigned long run;
        unsigned long sleep_millisecs;
        unsigned long stable_node_chains_prune_millisecs;
        unsigned long use_zero_pages;
};

enum ksm_merge_type {
        KSM_MERGE_MADVISE,
        KSM_MERGE_PRCTL,
        KSM_MERGE_LAST = KSM_MERGE_PRCTL
};

enum ksm_test_name {
        CHECK_KSM_MERGE,
        CHECK_KSM_UNMERGE,
        CHECK_KSM_GET_MERGE_TYPE,
        CHECK_KSM_ZERO_PAGE_MERGE,
        CHECK_KSM_NUMA_MERGE,
        KSM_MERGE_TIME,
        KSM_MERGE_TIME_HUGE_PAGES,
        KSM_UNMERGE_TIME,
        KSM_COW_TIME
};

int debug;

static int ksm_write_sysfs(const char *file_path, unsigned long val)
{
        return write_sysfs(file_path, val);
}

static int ksm_read_sysfs(const char *file_path, unsigned long *val)
{
        return read_sysfs(file_path, val);
}

static void ksm_print_sysfs(void)
{
        unsigned long max_page_sharing, pages_sharing, pages_shared;
        unsigned long full_scans, pages_unshared, pages_volatile;
        unsigned long stable_node_chains, stable_node_dups;
        long general_profit;

        if (ksm_read_sysfs(KSM_FP("pages_shared"), &pages_shared) ||
            ksm_read_sysfs(KSM_FP("pages_sharing"), &pages_sharing) ||
            ksm_read_sysfs(KSM_FP("max_page_sharing"), &max_page_sharing) ||
            ksm_read_sysfs(KSM_FP("full_scans"), &full_scans) ||
            ksm_read_sysfs(KSM_FP("pages_unshared"), &pages_unshared) ||
            ksm_read_sysfs(KSM_FP("pages_volatile"), &pages_volatile) ||
            ksm_read_sysfs(KSM_FP("stable_node_chains"), &stable_node_chains) ||
            ksm_read_sysfs(KSM_FP("stable_node_dups"), &stable_node_dups) ||
            ksm_read_sysfs(KSM_FP("general_profit"), (unsigned long *)&general_profit))
                return;

        printf("pages_shared      : %lu\n", pages_shared);
        printf("pages_sharing     : %lu\n", pages_sharing);
        printf("max_page_sharing  : %lu\n", max_page_sharing);
        printf("full_scans        : %lu\n", full_scans);
        printf("pages_unshared    : %lu\n", pages_unshared);
        printf("pages_volatile    : %lu\n", pages_volatile);
        printf("stable_node_chains: %lu\n", stable_node_chains);
        printf("stable_node_dups  : %lu\n", stable_node_dups);
        printf("general_profit    : %ld\n", general_profit);
}

static void ksm_print_procfs(void)
{
        const char *file_name = "/proc/self/ksm_stat";
        char buffer[512];
        FILE *f = fopen(file_name, "r");

        if (!f) {
                fprintf(stderr, "f %s\n", file_name);
                perror("fopen");
                return;
        }

        while (fgets(buffer, sizeof(buffer), f))
                printf("%s", buffer);

        fclose(f);
}

static int str_to_prot(char *prot_str)
{
        int prot = 0;

        if ((strchr(prot_str, 'r')) != NULL)
                prot |= PROT_READ;
        if ((strchr(prot_str, 'w')) != NULL)
                prot |= PROT_WRITE;
        if ((strchr(prot_str, 'x')) != NULL)
                prot |= PROT_EXEC;

        return prot;
}

static void print_help(void)
{
        printf("usage: ksm_tests [-h] <test type> [-a prot] [-p page_count] [-l timeout]\n"
               "[-z use_zero_pages] [-m merge_across_nodes] [-s size]\n");

        printf("Supported <test type>:\n"
               " -M (page merging)\n"
               " -Z (zero pages merging)\n"
               " -N (merging of pages in different NUMA nodes)\n"
               " -U (page unmerging)\n"
               " -P evaluate merging time and speed.\n"
               "    For this test, the size of duplicated memory area (in MiB)\n"
               "    must be provided using -s option\n"
               " -H evaluate merging time and speed of area allocated mostly with huge pages\n"
               "    For this test, the size of duplicated memory area (in MiB)\n"
               "    must be provided using -s option\n"
               " -D evaluate unmerging time and speed when disabling KSM.\n"
               "    For this test, the size of duplicated memory area (in MiB)\n"
               "    must be provided using -s option\n"
               " -C evaluate the time required to break COW of merged pages.\n\n");

        printf(" -a: specify the access protections of pages.\n"
               "     <prot> must be of the form [rwx].\n"
               "     Default: %s\n", KSM_PROT_STR_DEFAULT);
        printf(" -p: specify the number of pages to test.\n"
               "     Default: %ld\n", KSM_PAGE_COUNT_DEFAULT);
        printf(" -l: limit the maximum running time (in seconds) for a test.\n"
               "     Default: %d seconds\n", KSM_SCAN_LIMIT_SEC_DEFAULT);
        printf(" -z: change use_zero_pages tunable\n"
               "     Default: %d\n", KSM_USE_ZERO_PAGES_DEFAULT);
        printf(" -m: change merge_across_nodes tunable\n"
               "     Default: %d\n", KSM_MERGE_ACROSS_NODES_DEFAULT);
        printf(" -d: turn debugging output on\n");
        printf(" -s: the size of duplicated memory area (in MiB)\n");
        printf(" -t: KSM merge type\n"
               "     Default: 0\n"
               "     0: madvise merging\n"
               "     1: prctl merging\n");

        exit(0);
}

static void  *allocate_memory(void *ptr, int prot, int mapping, char data, size_t map_size)
{
        void *map_ptr = mmap(ptr, map_size, PROT_WRITE, mapping, -1, 0);

        if (!map_ptr) {
                perror("mmap");
                return NULL;
        }
        memset(map_ptr, data, map_size);
        if (mprotect(map_ptr, map_size, prot)) {
                perror("mprotect");
                munmap(map_ptr, map_size);
                return NULL;
        }

        return map_ptr;
}

static int ksm_do_scan(int scan_count, struct timespec start_time, int timeout)
{
        struct timespec cur_time;
        unsigned long cur_scan, init_scan;

        if (ksm_read_sysfs(KSM_FP("full_scans"), &init_scan))
                return 1;
        cur_scan = init_scan;

        while (cur_scan < init_scan + scan_count) {
                if (ksm_read_sysfs(KSM_FP("full_scans"), &cur_scan))
                        return 1;
                if (clock_gettime(CLOCK_MONOTONIC_RAW, &cur_time)) {
                        perror("clock_gettime");
                        return 1;
                }
                if ((cur_time.tv_sec - start_time.tv_sec) > timeout) {
                        printf("Scan time limit exceeded\n");
                        return 1;
                }
        }

        return 0;
}

static int ksm_merge_pages(int merge_type, void *addr, size_t size,
                        struct timespec start_time, int timeout)
{
        if (merge_type == KSM_MERGE_MADVISE) {
                if (madvise(addr, size, MADV_MERGEABLE)) {
                        perror("madvise");
                        return 1;
                }
        } else if (merge_type == KSM_MERGE_PRCTL) {
                if (prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0)) {
                        perror("prctl");
                        return 1;
                }
        }

        if (ksm_write_sysfs(KSM_FP("run"), 1))
                return 1;

        /* Since merging occurs only after 2 scans, make sure to get at least 2 full scans */
        if (ksm_do_scan(2, start_time, timeout))
                return 1;

        return 0;
}

static int ksm_unmerge_pages(void *addr, size_t size,
                             struct timespec start_time, int timeout)
{
        if (madvise(addr, size, MADV_UNMERGEABLE)) {
                perror("madvise");
                return 1;
        }
        return 0;
}

static bool assert_ksm_pages_count(long dupl_page_count)
{
        unsigned long max_page_sharing, pages_sharing, pages_shared;

        if (ksm_read_sysfs(KSM_FP("pages_shared"), &pages_shared) ||
            ksm_read_sysfs(KSM_FP("pages_sharing"), &pages_sharing) ||
            ksm_read_sysfs(KSM_FP("max_page_sharing"), &max_page_sharing))
                return false;

        if (debug) {
                ksm_print_sysfs();
                ksm_print_procfs();
        }

        /*
         * Since there must be at least 2 pages for merging and 1 page can be
         * shared with the limited number of pages (max_page_sharing), sometimes
         * there are 'leftover' pages that cannot be merged. For example, if there
         * are 11 pages and max_page_sharing = 10, then only 10 pages will be
         * merged and the 11th page won't be affected. As a result, when the number
         * of duplicate pages is divided by max_page_sharing and the remainder is 1,
         * pages_shared and pages_sharing values will be equal between dupl_page_count
         * and dupl_page_count - 1.
         */
        if (dupl_page_count % max_page_sharing == 1 || dupl_page_count % max_page_sharing == 0) {
                if (pages_shared == dupl_page_count / max_page_sharing &&
                    pages_sharing == pages_shared * (max_page_sharing - 1))
                        return true;
        } else {
                if (pages_shared == (dupl_page_count / max_page_sharing + 1) &&
                    pages_sharing == dupl_page_count - pages_shared)
                        return true;
        }

        return false;
}

static int ksm_save_def(struct ksm_sysfs *ksm_sysfs)
{
        if (ksm_read_sysfs(KSM_FP("max_page_sharing"), &ksm_sysfs->max_page_sharing) ||
            numa_available() ? 0 :
                ksm_read_sysfs(KSM_FP("merge_across_nodes"), &ksm_sysfs->merge_across_nodes) ||
            ksm_read_sysfs(KSM_FP("sleep_millisecs"), &ksm_sysfs->sleep_millisecs) ||
            ksm_read_sysfs(KSM_FP("pages_to_scan"), &ksm_sysfs->pages_to_scan) ||
            ksm_read_sysfs(KSM_FP("run"), &ksm_sysfs->run) ||
            ksm_read_sysfs(KSM_FP("stable_node_chains_prune_millisecs"),
                           &ksm_sysfs->stable_node_chains_prune_millisecs) ||
            ksm_read_sysfs(KSM_FP("use_zero_pages"), &ksm_sysfs->use_zero_pages))
                return 1;

        return 0;
}

static int ksm_restore(struct ksm_sysfs *ksm_sysfs)
{
        if (ksm_write_sysfs(KSM_FP("max_page_sharing"), ksm_sysfs->max_page_sharing) ||
            numa_available() ? 0 :
                ksm_write_sysfs(KSM_FP("merge_across_nodes"), ksm_sysfs->merge_across_nodes) ||
            ksm_write_sysfs(KSM_FP("pages_to_scan"), ksm_sysfs->pages_to_scan) ||
            ksm_write_sysfs(KSM_FP("run"), ksm_sysfs->run) ||
            ksm_write_sysfs(KSM_FP("sleep_millisecs"), ksm_sysfs->sleep_millisecs) ||
            ksm_write_sysfs(KSM_FP("stable_node_chains_prune_millisecs"),
                            ksm_sysfs->stable_node_chains_prune_millisecs) ||
            ksm_write_sysfs(KSM_FP("use_zero_pages"), ksm_sysfs->use_zero_pages))
                return 1;

        return 0;
}

static int check_ksm_merge(int merge_type, int mapping, int prot,
                        long page_count, int timeout, size_t page_size)
{
        void *map_ptr;
        struct timespec start_time;

        if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
                perror("clock_gettime");
                return KSFT_FAIL;
        }

        /* fill pages with the same data and merge them */
        map_ptr = allocate_memory(NULL, prot, mapping, '*', page_size * page_count);
        if (!map_ptr)
                return KSFT_FAIL;

        if (ksm_merge_pages(merge_type, map_ptr, page_size * page_count, start_time, timeout))
                goto err_out;

        /* verify that the right number of pages are merged */
        if (assert_ksm_pages_count(page_count)) {
                printf("OK\n");
                munmap(map_ptr, page_size * page_count);
                if (merge_type == KSM_MERGE_PRCTL)
                        prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0);
                return KSFT_PASS;
        }

err_out:
        printf("Not OK\n");
        munmap(map_ptr, page_size * page_count);
        return KSFT_FAIL;
}

static int check_ksm_unmerge(int merge_type, int mapping, int prot, int timeout, size_t page_size)
{
        void *map_ptr;
        struct timespec start_time;
        int page_count = 2;

        if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
                perror("clock_gettime");
                return KSFT_FAIL;
        }

        /* fill pages with the same data and merge them */
        map_ptr = allocate_memory(NULL, prot, mapping, '*', page_size * page_count);
        if (!map_ptr)
                return KSFT_FAIL;

        if (ksm_merge_pages(merge_type, map_ptr, page_size * page_count, start_time, timeout))
                goto err_out;

        /* change 1 byte in each of the 2 pages -- KSM must automatically unmerge them */
        memset(map_ptr, '-', 1);
        memset(map_ptr + page_size, '+', 1);

        /* get at least 1 scan, so KSM can detect that the pages were modified */
        if (ksm_do_scan(1, start_time, timeout))
                goto err_out;

        /* check that unmerging was successful and 0 pages are currently merged */
        if (assert_ksm_pages_count(0)) {
                printf("OK\n");
                munmap(map_ptr, page_size * page_count);
                return KSFT_PASS;
        }

err_out:
        printf("Not OK\n");
        munmap(map_ptr, page_size * page_count);
        return KSFT_FAIL;
}

static int check_ksm_zero_page_merge(int merge_type, int mapping, int prot, long page_count,
                                int timeout, bool use_zero_pages, size_t page_size)
{
        void *map_ptr;
        struct timespec start_time;

        if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
                perror("clock_gettime");
                return KSFT_FAIL;
        }

        if (ksm_write_sysfs(KSM_FP("use_zero_pages"), use_zero_pages))
                return KSFT_FAIL;

        /* fill pages with zero and try to merge them */
        map_ptr = allocate_memory(NULL, prot, mapping, 0, page_size * page_count);
        if (!map_ptr)
                return KSFT_FAIL;

        if (ksm_merge_pages(merge_type, map_ptr, page_size * page_count, start_time, timeout))
                goto err_out;

       /*
        * verify that the right number of pages are merged:
        * 1) if use_zero_pages is set to 1, empty pages are merged
        *    with the kernel zero page instead of with each other;
        * 2) if use_zero_pages is set to 0, empty pages are not treated specially
        *    and merged as usual.
        */
        if (use_zero_pages && !assert_ksm_pages_count(0))
                goto err_out;
        else if (!use_zero_pages && !assert_ksm_pages_count(page_count))
                goto err_out;

        printf("OK\n");
        munmap(map_ptr, page_size * page_count);
        return KSFT_PASS;

err_out:
        printf("Not OK\n");
        munmap(map_ptr, page_size * page_count);
        return KSFT_FAIL;
}

static int get_next_mem_node(int node)
{

        long node_size;
        int mem_node = 0;
        int i, max_node = numa_max_node();

        for (i = node + 1; i <= max_node + node; i++) {
                mem_node = i % (max_node + 1);
                node_size = numa_node_size(mem_node, NULL);
                if (node_size > 0)
                        break;
        }
        return mem_node;
}

static int get_first_mem_node(void)
{
        return get_next_mem_node(numa_max_node());
}

static int check_ksm_numa_merge(int merge_type, int mapping, int prot, int timeout,
                                bool merge_across_nodes, size_t page_size)
{
        void *numa1_map_ptr, *numa2_map_ptr;
        struct timespec start_time;
        int page_count = 2;
        int first_node;

        if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
                perror("clock_gettime");
                return KSFT_FAIL;
        }

        if (numa_available() < 0) {
                perror("NUMA support not enabled");
                return KSFT_SKIP;
        }
        if (numa_num_configured_nodes() <= 1) {
                printf("At least 2 NUMA nodes must be available\n");
                return KSFT_SKIP;
        }
        if (ksm_write_sysfs(KSM_FP("merge_across_nodes"), merge_across_nodes))
                return KSFT_FAIL;

        /* allocate 2 pages in 2 different NUMA nodes and fill them with the same data */
        first_node = get_first_mem_node();
        numa1_map_ptr = numa_alloc_onnode(page_size, first_node);
        numa2_map_ptr = numa_alloc_onnode(page_size, get_next_mem_node(first_node));
        if (!numa1_map_ptr || !numa2_map_ptr) {
                perror("numa_alloc_onnode");
                return KSFT_FAIL;
        }

        memset(numa1_map_ptr, '*', page_size);
        memset(numa2_map_ptr, '*', page_size);

        /* try to merge the pages */
        if (ksm_merge_pages(merge_type, numa1_map_ptr, page_size, start_time, timeout) ||
            ksm_merge_pages(merge_type, numa2_map_ptr, page_size, start_time, timeout))
                goto err_out;

       /*
        * verify that the right number of pages are merged:
        * 1) if merge_across_nodes was enabled, 2 duplicate pages will be merged;
        * 2) if merge_across_nodes = 0, there must be 0 merged pages, since there is
        *    only 1 unique page in each node and they can't be shared.
        */
        if (merge_across_nodes && !assert_ksm_pages_count(page_count))
                goto err_out;
        else if (!merge_across_nodes && !assert_ksm_pages_count(0))
                goto err_out;

        numa_free(numa1_map_ptr, page_size);
        numa_free(numa2_map_ptr, page_size);
        printf("OK\n");
        return KSFT_PASS;

err_out:
        numa_free(numa1_map_ptr, page_size);
        numa_free(numa2_map_ptr, page_size);
        printf("Not OK\n");
        return KSFT_FAIL;
}

static int ksm_merge_hugepages_time(int merge_type, int mapping, int prot,
                                int timeout, size_t map_size)
{
        void *map_ptr, *map_ptr_orig;
        struct timespec start_time, end_time;
        unsigned long scan_time_ns;
        int pagemap_fd, n_normal_pages, n_huge_pages;

        if (!thp_is_enabled()) {
                printf("Transparent Hugepages not available\n");
                return KSFT_SKIP;
        }

        map_size *= MB;
        size_t len = map_size;

        len -= len % HPAGE_SIZE;
        map_ptr_orig = mmap(NULL, len + HPAGE_SIZE, PROT_READ | PROT_WRITE,
                        MAP_ANONYMOUS | MAP_NORESERVE | MAP_PRIVATE, -1, 0);
        map_ptr = map_ptr_orig + HPAGE_SIZE - (uintptr_t)map_ptr_orig % HPAGE_SIZE;

        if (map_ptr_orig == MAP_FAILED)
                err(2, "initial mmap");

        if (madvise(map_ptr, len, MADV_HUGEPAGE))
                err(2, "MADV_HUGEPAGE");

        pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
        if (pagemap_fd < 0)
                err(2, "open pagemap");

        n_normal_pages = 0;
        n_huge_pages = 0;
        for (void *p = map_ptr; p < map_ptr + len; p += HPAGE_SIZE) {
                if (allocate_transhuge(p, pagemap_fd) < 0)
                        n_normal_pages++;
                else
                        n_huge_pages++;
        }
        printf("Number of normal pages:    %d\n", n_normal_pages);
        printf("Number of huge pages:    %d\n", n_huge_pages);

        memset(map_ptr, '*', len);

        if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
                perror("clock_gettime");
                goto err_out;
        }
        if (ksm_merge_pages(merge_type, map_ptr, map_size, start_time, timeout))
                goto err_out;
        if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
                perror("clock_gettime");
                goto err_out;
        }

        scan_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
                       (end_time.tv_nsec - start_time.tv_nsec);

        printf("Total size:    %lu MiB\n", map_size / MB);
        printf("Total time:    %ld.%09ld s\n", scan_time_ns / NSEC_PER_SEC,
               scan_time_ns % NSEC_PER_SEC);
        printf("Average speed:  %.3f MiB/s\n", (map_size / MB) /
                                               ((double)scan_time_ns / NSEC_PER_SEC));

        munmap(map_ptr_orig, len + HPAGE_SIZE);
        return KSFT_PASS;

err_out:
        printf("Not OK\n");
        munmap(map_ptr_orig, len + HPAGE_SIZE);
        return KSFT_FAIL;
}

static int ksm_merge_time(int merge_type, int mapping, int prot, int timeout, size_t map_size)
{
        void *map_ptr;
        struct timespec start_time, end_time;
        unsigned long scan_time_ns;

        map_size *= MB;

        map_ptr = allocate_memory(NULL, prot, mapping, '*', map_size);
        if (!map_ptr)
                return KSFT_FAIL;

        if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
                perror("clock_gettime");
                goto err_out;
        }
        if (ksm_merge_pages(merge_type, map_ptr, map_size, start_time, timeout))
                goto err_out;
        if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
                perror("clock_gettime");
                goto err_out;
        }

        scan_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
                       (end_time.tv_nsec - start_time.tv_nsec);

        printf("Total size:    %lu MiB\n", map_size / MB);
        printf("Total time:    %ld.%09ld s\n", scan_time_ns / NSEC_PER_SEC,
               scan_time_ns % NSEC_PER_SEC);
        printf("Average speed:  %.3f MiB/s\n", (map_size / MB) /
                                               ((double)scan_time_ns / NSEC_PER_SEC));

        munmap(map_ptr, map_size);
        return KSFT_PASS;

err_out:
        printf("Not OK\n");
        munmap(map_ptr, map_size);
        return KSFT_FAIL;
}

static int ksm_unmerge_time(int merge_type, int mapping, int prot, int timeout, size_t map_size)
{
        void *map_ptr;
        struct timespec start_time, end_time;
        unsigned long scan_time_ns;

        map_size *= MB;

        map_ptr = allocate_memory(NULL, prot, mapping, '*', map_size);
        if (!map_ptr)
                return KSFT_FAIL;
        if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
                perror("clock_gettime");
                goto err_out;
        }
        if (ksm_merge_pages(merge_type, map_ptr, map_size, start_time, timeout))
                goto err_out;

        if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
                perror("clock_gettime");
                goto err_out;
        }
        if (ksm_unmerge_pages(map_ptr, map_size, start_time, timeout))
                goto err_out;
        if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
                perror("clock_gettime");
                goto err_out;
        }

        scan_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
                       (end_time.tv_nsec - start_time.tv_nsec);

        printf("Total size:    %lu MiB\n", map_size / MB);
        printf("Total time:    %ld.%09ld s\n", scan_time_ns / NSEC_PER_SEC,
               scan_time_ns % NSEC_PER_SEC);
        printf("Average speed:  %.3f MiB/s\n", (map_size / MB) /
                                               ((double)scan_time_ns / NSEC_PER_SEC));

        munmap(map_ptr, map_size);
        return KSFT_PASS;

err_out:
        printf("Not OK\n");
        munmap(map_ptr, map_size);
        return KSFT_FAIL;
}

static int ksm_cow_time(int merge_type, int mapping, int prot, int timeout, size_t page_size)
{
        void *map_ptr;
        struct timespec start_time, end_time;
        unsigned long cow_time_ns;

        /* page_count must be less than 2*page_size */
        size_t page_count = 4000;

        map_ptr = allocate_memory(NULL, prot, mapping, '*', page_size * page_count);
        if (!map_ptr)
                return KSFT_FAIL;

        if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
                perror("clock_gettime");
                return KSFT_FAIL;
        }
        for (size_t i = 0; i < page_count - 1; i = i + 2)
                memset(map_ptr + page_size * i, '-', 1);
        if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
                perror("clock_gettime");
                return KSFT_FAIL;
        }

        cow_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
                       (end_time.tv_nsec - start_time.tv_nsec);

        printf("Total size:    %lu MiB\n\n", (page_size * page_count) / MB);
        printf("Not merged pages:\n");
        printf("Total time:     %ld.%09ld s\n", cow_time_ns / NSEC_PER_SEC,
               cow_time_ns % NSEC_PER_SEC);
        printf("Average speed:  %.3f MiB/s\n\n", ((page_size * (page_count / 2)) / MB) /
                                               ((double)cow_time_ns / NSEC_PER_SEC));

        /* Create 2000 pairs of duplicate pages */
        for (size_t i = 0; i < page_count - 1; i = i + 2) {
                memset(map_ptr + page_size * i, '+', i / 2 + 1);
                memset(map_ptr + page_size * (i + 1), '+', i / 2 + 1);
        }
        if (ksm_merge_pages(merge_type, map_ptr, page_size * page_count, start_time, timeout))
                goto err_out;

        if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
                perror("clock_gettime");
                goto err_out;
        }
        for (size_t i = 0; i < page_count - 1; i = i + 2)
                memset(map_ptr + page_size * i, '-', 1);
        if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
                perror("clock_gettime");
                goto err_out;
        }

        cow_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
                       (end_time.tv_nsec - start_time.tv_nsec);

        printf("Merged pages:\n");
        printf("Total time:     %ld.%09ld s\n", cow_time_ns / NSEC_PER_SEC,
               cow_time_ns % NSEC_PER_SEC);
        printf("Average speed:  %.3f MiB/s\n", ((page_size * (page_count / 2)) / MB) /
                                               ((double)cow_time_ns / NSEC_PER_SEC));

        munmap(map_ptr, page_size * page_count);
        return KSFT_PASS;

err_out:
        printf("Not OK\n");
        munmap(map_ptr, page_size * page_count);
        return KSFT_FAIL;
}

int main(int argc, char *argv[])
{
        int ret = 0, opt;
        int prot = 0;
        int ksm_scan_limit_sec = KSM_SCAN_LIMIT_SEC_DEFAULT;
        int merge_type = KSM_MERGE_TYPE_DEFAULT;
        long page_count = KSM_PAGE_COUNT_DEFAULT;
        size_t page_size = sysconf(_SC_PAGESIZE);
        struct ksm_sysfs ksm_sysfs_old;
        int test_name = CHECK_KSM_MERGE;
        bool use_zero_pages = KSM_USE_ZERO_PAGES_DEFAULT;
        bool merge_across_nodes = KSM_MERGE_ACROSS_NODES_DEFAULT;
        long size_MB = 0;

        while ((opt = getopt(argc, argv, "dha:p:l:z:m:s:t:MUZNPCHD")) != -1) {
                switch (opt) {
                case 'a':
                        prot = str_to_prot(optarg);
                        break;
                case 'p':
                        page_count = atol(optarg);
                        if (page_count <= 0) {
                                printf("The number of pages must be greater than 0\n");
                                return KSFT_FAIL;
                        }
                        break;
                case 'l':
                        ksm_scan_limit_sec = atoi(optarg);
                        if (ksm_scan_limit_sec <= 0) {
                                printf("Timeout value must be greater than 0\n");
                                return KSFT_FAIL;
                        }
                        break;
                case 'h':
                        print_help();
                        break;
                case 'z':
                        if (strcmp(optarg, "0") == 0)
                                use_zero_pages = 0;
                        else
                                use_zero_pages = 1;
                        break;
                case 'm':
                        if (strcmp(optarg, "0") == 0)
                                merge_across_nodes = 0;
                        else
                                merge_across_nodes = 1;
                        break;
                case 'd':
                        debug = 1;
                        break;
                case 's':
                        size_MB = atoi(optarg);
                        if (size_MB <= 0) {
                                printf("Size must be greater than 0\n");
                                return KSFT_FAIL;
                        }
                        break;
                case 't':
                        {
                                int tmp = atoi(optarg);

                                if (tmp < 0 || tmp > KSM_MERGE_LAST) {
                                        printf("Invalid merge type\n");
                                        return KSFT_FAIL;
                                }
                                merge_type = tmp;
                        }
                        break;
                case 'M':
                        break;
                case 'U':
                        test_name = CHECK_KSM_UNMERGE;
                        break;
                case 'Z':
                        test_name = CHECK_KSM_ZERO_PAGE_MERGE;
                        break;
                case 'N':
                        test_name = CHECK_KSM_NUMA_MERGE;
                        break;
                case 'P':
                        test_name = KSM_MERGE_TIME;
                        break;
                case 'H':
                        test_name = KSM_MERGE_TIME_HUGE_PAGES;
                        break;
                case 'D':
                        test_name = KSM_UNMERGE_TIME;
                        break;
                case 'C':
                        test_name = KSM_COW_TIME;
                        break;
                default:
                        return KSFT_FAIL;
                }
        }

        if (prot == 0)
                prot = str_to_prot(KSM_PROT_STR_DEFAULT);

        if (access(KSM_SYSFS_PATH, F_OK)) {
                printf("Config KSM not enabled\n");
                return KSFT_SKIP;
        }

        if (ksm_save_def(&ksm_sysfs_old)) {
                printf("Cannot save default tunables\n");
                return KSFT_FAIL;
        }

        if (ksm_write_sysfs(KSM_FP("run"), 2) ||
            ksm_write_sysfs(KSM_FP("sleep_millisecs"), 0) ||
            numa_available() ? 0 :
                ksm_write_sysfs(KSM_FP("merge_across_nodes"), 1) ||
            ksm_write_sysfs(KSM_FP("pages_to_scan"), page_count))
                return KSFT_FAIL;

        switch (test_name) {
        case CHECK_KSM_MERGE:
                ret = check_ksm_merge(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot, page_count,
                                      ksm_scan_limit_sec, page_size);
                break;
        case CHECK_KSM_UNMERGE:
                ret = check_ksm_unmerge(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
                                        ksm_scan_limit_sec, page_size);
                break;
        case CHECK_KSM_ZERO_PAGE_MERGE:
                ret = check_ksm_zero_page_merge(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
                                                page_count, ksm_scan_limit_sec, use_zero_pages,
                                                page_size);
                break;
        case CHECK_KSM_NUMA_MERGE:
                ret = check_ksm_numa_merge(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
                                        ksm_scan_limit_sec, merge_across_nodes, page_size);
                break;
        case KSM_MERGE_TIME:
                if (size_MB == 0) {
                        printf("Option '-s' is required.\n");
                        return KSFT_FAIL;
                }
                ret = ksm_merge_time(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
                                ksm_scan_limit_sec, size_MB);
                break;
        case KSM_MERGE_TIME_HUGE_PAGES:
                if (size_MB == 0) {
                        printf("Option '-s' is required.\n");
                        return KSFT_FAIL;
                }
                ret = ksm_merge_hugepages_time(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
                                ksm_scan_limit_sec, size_MB);
                break;
        case KSM_UNMERGE_TIME:
                if (size_MB == 0) {
                        printf("Option '-s' is required.\n");
                        return KSFT_FAIL;
                }
                ret = ksm_unmerge_time(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
                                       ksm_scan_limit_sec, size_MB);
                break;
        case KSM_COW_TIME:
                ret = ksm_cow_time(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
                                ksm_scan_limit_sec, page_size);
                break;
        }

        if (ksm_restore(&ksm_sysfs_old)) {
                printf("Cannot restore default tunables\n");
                return KSFT_FAIL;
        }

        return ret;
}