Re: [PATCH v2 4/4] selftests: vm: add KSM merging across nodes test

From: Tyler Hicks
Date: Mon Aug 16 2021 - 10:28:36 EST

On 2021-07-14 14:56:18, Zhansaya Bagdauletkyzy wrote:
> Add check_ksm_numa_merge() function to test that pages in different NUMA
> nodes are being handled properly. First, two duplicate pages are allocated
> in two separate NUMA nodes using the libnuma library. Since there is one
> unique page in each node, with merge_across_nodes = 0, there won't be any
> shared pages. If merge_across_nodes is set to 1, the pages will be
> treated as usual duplicate pages and will be merged. If NUMA config is
> not enabled or the number of NUMA nodes is less than two, then the test
> is skipped. The test is run as follows: ./ksm_tests -N
>
> Signed-off-by: Zhansaya Bagdauletkyzy <zhansayabagdaulet@xxxxxxxxx>

Reviewed-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>

Tyler

> ---
> tools/testing/selftests/vm/Makefile | 2 +
> tools/testing/selftests/vm/ksm_tests.c | 88 ++++++++++++++++++++++-
> tools/testing/selftests/vm/run_vmtests.sh | 32 +++++++++
> 3 files changed, 119 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
> index e6f22a801b71..d9605bd10f2d 100644
> --- a/tools/testing/selftests/vm/Makefile
> +++ b/tools/testing/selftests/vm/Makefile
> @@ -146,6 +146,8 @@ $(OUTPUT)/hmm-tests: local_config.h
> # HMM_EXTRA_LIBS may get set in local_config.mk, or it may be left empty.
> $(OUTPUT)/hmm-tests: LDLIBS += $(HMM_EXTRA_LIBS)
>
> +$(OUTPUT)/ksm_tests: LDLIBS += -lnuma
> +
> local_config.mk local_config.h: check_config.sh
> /bin/sh ./check_config.sh $(CC)
>
> diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
> index 5843526471e1..cdeb4a028538 100644
> --- a/tools/testing/selftests/vm/ksm_tests.c
> +++ b/tools/testing/selftests/vm/ksm_tests.c
> @@ -4,6 +4,7 @@
> #include <stdbool.h>
> #include <time.h>
> #include <string.h>
> +#include <numa.h>
>
> #include "../kselftest.h"
>
> @@ -13,6 +14,7 @@
> #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
>
> struct ksm_sysfs {
> unsigned long max_page_sharing;
> @@ -27,7 +29,8 @@ struct ksm_sysfs {
> enum ksm_test_name {
> CHECK_KSM_MERGE,
> CHECK_KSM_UNMERGE,
> - CHECK_KSM_ZERO_PAGE_MERGE
> + CHECK_KSM_ZERO_PAGE_MERGE,
> + CHECK_KSM_NUMA_MERGE
> };
>
> static int ksm_write_sysfs(const char *file_path, unsigned long val)
> @@ -83,11 +86,12 @@ 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"
> - "[-z use_zero_pages]\n");
> + "[-z use_zero_pages] [-m merge_across_nodes]\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\n");
>
> printf(" -a: specify the access protections of pages.\n"
> @@ -99,6 +103,8 @@ static void print_help(void)
> " 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);
>
> exit(0);
> }
> @@ -339,6 +345,68 @@ static int check_ksm_zero_page_merge(int mapping, int prot, long page_count, int
> return KSFT_FAIL;
> }
>
> +static int check_ksm_numa_merge(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;
> +
> + 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_max_node() < 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 */
> + numa1_map_ptr = numa_alloc_onnode(page_size, 0);
> + numa2_map_ptr = numa_alloc_onnode(page_size, 1);
> + 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(numa1_map_ptr, page_size, start_time, timeout) ||
> + ksm_merge_pages(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;
> +}
> +
> int main(int argc, char *argv[])
> {
> int ret, opt;
> @@ -349,8 +417,9 @@ int main(int argc, char *argv[])
> 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;
>
> - while ((opt = getopt(argc, argv, "ha:p:l:z:MUZ")) != -1) {
> + while ((opt = getopt(argc, argv, "ha:p:l:z:m:MUZN")) != -1) {
> switch (opt) {
> case 'a':
> prot = str_to_prot(optarg);
> @@ -378,6 +447,12 @@ int main(int argc, char *argv[])
> else
> use_zero_pages = 1;
> break;
> + case 'm':
> + if (strcmp(optarg, "0") == 0)
> + merge_across_nodes = 0;
> + else
> + merge_across_nodes = 1;
> + break;
> case 'M':
> break;
> case 'U':
> @@ -386,6 +461,9 @@ int main(int argc, char *argv[])
> case 'Z':
> test_name = CHECK_KSM_ZERO_PAGE_MERGE;
> break;
> + case 'N':
> + test_name = CHECK_KSM_NUMA_MERGE;
> + break;
> default:
> return KSFT_FAIL;
> }
> @@ -423,6 +501,10 @@ int main(int argc, char *argv[])
> ret = check_ksm_zero_page_merge(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(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
> + merge_across_nodes, 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 9b4e444fc4ed..45e803af7c77 100755
> --- a/tools/testing/selftests/vm/run_vmtests.sh
> +++ b/tools/testing/selftests/vm/run_vmtests.sh
> @@ -441,6 +441,38 @@ else
> exitcode=1
> fi
>
> +echo "-------------------------------------------------------------"
> +echo "running KSM test with 2 NUMA nodes and merge_across_nodes = 1"
> +echo "-------------------------------------------------------------"
> +./ksm_tests -N -m 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
> +
> +echo "-------------------------------------------------------------"
> +echo "running KSM test with 2 NUMA nodes and merge_across_nodes = 0"
> +echo "-------------------------------------------------------------"
> +./ksm_tests -N -m 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
> +
> exit $exitcode
>
> exit $exitcode
> --
> 2.25.1
>