Re: [PATCH v2 3/4] selftests: vm: add KSM zero page merging test

On 2021-07-14 14:56:14, Zhansaya Bagdauletkyzy wrote:

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@gmail.com

Reviewed-by: Tyler Hicks tyhicks@linux.microsoft.com

Tyler

---

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