[patch 178/262] selftests: vm: add KSM huge pages merging time test

Andrew Morton
2021-11-05T20:44:01Z

From: Pedro Demarchi Gomes <pedrodemargomes@gmail.com>
Subject: selftests: vm: add KSM huge pages merging time test

Add test case of KSM merging time using mostly huge pages

Link: https://lkml.kernel.org/r/20211013044045.360251-1-pedrodemargomes@gmail.com
Signed-off-by: Pedro Demarchi Gomes <pedrodemargomes@gmail.com>
Cc: Zhansaya Bagdauletkyzy <zhansayabagdaulet@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

tools/testing/selftests/vm/ksm_tests.c | 125 ++++++++++++++++++++++-
1 file changed, 124 insertions(+), 1 deletion(-)

--- a/tools/testing/selftests/vm/ksm_tests.c~selftests-vm-add-ksm-huge-pages-merging-time-test
+++ a/tools/testing/selftests/vm/ksm_tests.c
@@ -5,6 +5,10 @@
#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"
@@ -18,6 +22,15 @@
#define KSM_MERGE_ACROSS_NODES_DEFAULT true
#define MB (1ul << 20)

+#define PAGE_SHIFT 12
+#define HPAGE_SHIFT 21
+
+#define PAGE_SIZE (1 << PAGE_SHIFT)
+#define HPAGE_SIZE (1 << HPAGE_SHIFT)
+
+#define PAGEMAP_PRESENT(ent) (((ent) & (1ull << 63)) != 0)
+#define PAGEMAP_PFN(ent) ((ent) & ((1ull << 55) - 1))
+
struct ksm_sysfs {
unsigned long max_page_sharing;
unsigned long merge_across_nodes;
@@ -34,6 +47,7 @@ enum ksm_test_name {
CHECK_KSM_ZERO_PAGE_MERGE,
CHECK_KSM_NUMA_MERGE,
KSM_MERGE_TIME,
+ KSM_MERGE_TIME_HUGE_PAGES,
KSM_COW_TIME
};

@@ -100,6 +114,9 @@ static void print_help(void)
" -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"
" -C evaluate the time required to break COW of merged pages.\n\n");

printf(" -a: specify the access protections of pages.\n"
@@ -439,6 +456,101 @@ err_out:
return KSFT_FAIL;
}

+int64_t allocate_transhuge(void *ptr, int pagemap_fd)
+{
+ uint64_t ent[2];
+
+ /* drop pmd */
+ if (mmap(ptr, HPAGE_SIZE, PROT_READ | PROT_WRITE,
+ MAP_FIXED | MAP_ANONYMOUS |
+ MAP_NORESERVE | MAP_PRIVATE, -1, 0) != ptr)
+ errx(2, "mmap transhuge");
+
+ if (madvise(ptr, HPAGE_SIZE, MADV_HUGEPAGE))
+ err(2, "MADV_HUGEPAGE");
+
+ /* allocate transparent huge page */
+ *(volatile void **)ptr = ptr;
+
+ if (pread(pagemap_fd, ent, sizeof(ent),
+ (uintptr_t)ptr >> (PAGE_SHIFT - 3)) != sizeof(ent))
+ err(2, "read pagemap");
+
+ if (PAGEMAP_PRESENT(ent[0]) && PAGEMAP_PRESENT(ent[1]) &&
+ PAGEMAP_PFN(ent[0]) + 1 == PAGEMAP_PFN(ent[1]) &&
+ !(PAGEMAP_PFN(ent[0]) & ((1 << (HPAGE_SHIFT - PAGE_SHIFT)) - 1)))
+ return PAGEMAP_PFN(ent[0]);
+
+ return -1;
+}
+
+static int ksm_merge_hugepages_time(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;
+
+ 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 + HPAGE_SIZE, 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(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 mapping, int prot, int timeout, size_t map_size)
{
void *map_ptr;
@@ -564,7 +676,7 @@ int main(int argc, char *argv[])
bool merge_across_nodes = KSM_MERGE_ACROSS_NODES_DEFAULT;
long size_MB = 0;

- while ((opt = getopt(argc, argv, "ha:p:l:z:m:s:MUZNPC")) != -1) {
+ while ((opt = getopt(argc, argv, "ha:p:l:z:m:s:MUZNPCH")) != -1) {
switch (opt) {
case 'a':
prot = str_to_prot(optarg);
@@ -618,6 +730,9 @@ int main(int argc, char *argv[])
case 'P':
test_name = KSM_MERGE_TIME;
break;
+ case 'H':
+ test_name = KSM_MERGE_TIME_HUGE_PAGES;
+ break;
case 'C':
test_name = KSM_COW_TIME;
break;
@@ -670,6 +785,14 @@ int main(int argc, char *argv[])
ret = ksm_merge_time(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(MAP_PRIVATE | MAP_ANONYMOUS, prot,
+ ksm_scan_limit_sec, size_MB);
+ break;
case KSM_COW_TIME:
ret = ksm_cow_time(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
page_size);
_