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Message-ID: <6d0caab00d4bdccf5e3791cb95cf6dfd5eb85e45.1626252248.git.zhansayabagdaulet@gmail.com>
Date: Wed, 14 Jul 2021 14:56:14 +0600
From: Zhansaya Bagdauletkyzy <zhansayabagdaulet@...il.com>
To: shuah@...nel.org, akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
linux-mm@...ck.org, tyhicks@...ux.microsoft.com,
pasha.tatashin@...een.com
Subject: [PATCH v2 3/4] selftests: vm: add KSM zero page merging test
Add check_ksm_zero_page_merge() function to test that empty pages are
being handled properly. For this, several zero pages are allocated and
merged using madvise. If use_zero_pages is enabled, the pages must be
shared with the special kernel zero pages; otherwise, they are merged
as usual duplicate pages. The test is run as follows: ./ksm_tests -Z
Signed-off-by: Zhansaya Bagdauletkyzy <zhansayabagdaulet@...il.com>
---
tools/testing/selftests/vm/ksm_tests.c | 70 ++++++++++++++++++++++-
tools/testing/selftests/vm/run_vmtests.sh | 32 +++++++++++
2 files changed, 99 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
index 80302bb8f64c..5843526471e1 100644
--- a/tools/testing/selftests/vm/ksm_tests.c
+++ b/tools/testing/selftests/vm/ksm_tests.c
@@ -12,6 +12,7 @@
#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
struct ksm_sysfs {
unsigned long max_page_sharing;
@@ -25,7 +26,8 @@ struct ksm_sysfs {
enum ksm_test_name {
CHECK_KSM_MERGE,
- CHECK_KSM_UNMERGE
+ CHECK_KSM_UNMERGE,
+ CHECK_KSM_ZERO_PAGE_MERGE
};
static int ksm_write_sysfs(const char *file_path, unsigned long val)
@@ -80,10 +82,12 @@ static int str_to_prot(char *prot_str)
static void print_help(void)
{
- printf("usage: ksm_tests [-h] <test type> [-a prot] [-p page_count] [-l timeout]\n");
+ printf("usage: ksm_tests [-h] <test type> [-a prot] [-p page_count] [-l timeout]\n"
+ "[-z use_zero_pages]\n");
printf("Supported <test type>:\n"
" -M (page merging)\n"
+ " -Z (zero pages merging)\n"
" -U (page unmerging)\n\n");
printf(" -a: specify the access protections of pages.\n"
@@ -93,6 +97,8 @@ static void print_help(void)
" 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);
exit(0);
}
@@ -289,6 +295,50 @@ static int check_ksm_unmerge(int mapping, int prot, int timeout, size_t page_siz
return KSFT_FAIL;
}
+static int check_ksm_zero_page_merge(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(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;
+}
+
int main(int argc, char *argv[])
{
int ret, opt;
@@ -298,8 +348,9 @@ int main(int argc, char *argv[])
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;
- while ((opt = getopt(argc, argv, "ha:p:l:MU")) != -1) {
+ while ((opt = getopt(argc, argv, "ha:p:l:z:MUZ")) != -1) {
switch (opt) {
case 'a':
prot = str_to_prot(optarg);
@@ -321,11 +372,20 @@ int main(int argc, char *argv[])
case 'h':
print_help();
break;
+ case 'z':
+ if (strcmp(optarg, "0") == 0)
+ use_zero_pages = 0;
+ else
+ use_zero_pages = 1;
+ break;
case 'M':
break;
case 'U':
test_name = CHECK_KSM_UNMERGE;
break;
+ case 'Z':
+ test_name = CHECK_KSM_ZERO_PAGE_MERGE;
+ break;
default:
return KSFT_FAIL;
}
@@ -359,6 +419,10 @@ int main(int argc, char *argv[])
ret = check_ksm_unmerge(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
page_size);
break;
+ case CHECK_KSM_ZERO_PAGE_MERGE:
+ ret = check_ksm_zero_page_merge(MAP_PRIVATE | MAP_ANONYMOUS, prot, page_count,
+ ksm_scan_limit_sec, use_zero_pages, page_size);
+ break;
}
if (ksm_restore(&ksm_sysfs_old)) {
diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh
index 3a23c6b47da2..9b4e444fc4ed 100755
--- a/tools/testing/selftests/vm/run_vmtests.sh
+++ b/tools/testing/selftests/vm/run_vmtests.sh
@@ -409,6 +409,38 @@ else
exitcode=1
fi
+echo "----------------------------------------------------------"
+echo "running KSM test with 10 zero pages and use_zero_pages = 0"
+echo "----------------------------------------------------------"
+./ksm_tests -Z -p 10 -z 0
+ret_val=$?
+
+if [ $ret_val -eq 0 ]; then
+ echo "[PASS]"
+elif [ $ret_val -eq $ksft_skip ]; then
+ echo "[SKIP]"
+ exitcode=$ksft_skip
+else
+ echo "[FAIL]"
+ exitcode=1
+fi
+
+echo "----------------------------------------------------------"
+echo "running KSM test with 10 zero pages and use_zero_pages = 1"
+echo "----------------------------------------------------------"
+./ksm_tests -Z -p 10 -z 1
+ret_val=$?
+
+if [ $ret_val -eq 0 ]; then
+ echo "[PASS]"
+elif [ $ret_val -eq $ksft_skip ]; then
+ echo "[SKIP]"
+ exitcode=$ksft_skip
+else
+ echo "[FAIL]"
+ exitcode=1
+fi
+
exit $exitcode
exit $exitcode
--
2.25.1
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