selftests: vm: add KSM merging time test

Patch series "add KSM performance tests", v3.

Extend KSM self tests with a performance benchmark.  These tests are not
part of regular regression testing, as they are mainly intended to be used
by developers making changes to the memory management subsystem.

This patch (of 2):

Add ksm_merge_time() function to determine speed and time needed for
merging.  The total spent time is shown in seconds while speed is in
MiB/s.  User must specify the size of duplicated memory area (in MiB)
before running the test.

The test is run as follows: ./ksm_tests -P -s 100
The output:
	Total size:    100 MiB
	Total time:    0.201106786 s
	Average speed:  497.248 MiB/s

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/318b946ac80cc9205c89d0962048378f7ce0705b.1629386192.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy <[email protected]>
Reviewed-by: Tyler Hicks <[email protected]>
Reviewed-by: Pavel Tatashin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

tools/testing/selftests/vm/ksm_tests.c

@@ -7,6 +7,7 @@
 #include <numa.h>
 
 #include "../kselftest.h"
+#include "../../../../include/vdso/time64.h"
 
 #define KSM_SYSFS_PATH "/sys/kernel/mm/ksm/"
 #define KSM_FP(s) (KSM_SYSFS_PATH s)
@@ -15,6 +16,7 @@
 #define KSM_PROT_STR_DEFAULT "rw"
 #define KSM_USE_ZERO_PAGES_DEFAULT false
 #define KSM_MERGE_ACROSS_NODES_DEFAULT true
+#define MB (1ul << 20)
 
 struct ksm_sysfs {
 	unsigned long max_page_sharing;
@@ -30,7 +32,8 @@ enum ksm_test_name {
 	CHECK_KSM_MERGE,
 	CHECK_KSM_UNMERGE,
 	CHECK_KSM_ZERO_PAGE_MERGE,
-	CHECK_KSM_NUMA_MERGE
+	CHECK_KSM_NUMA_MERGE,
+	KSM_MERGE_TIME
 };
 
 static int ksm_write_sysfs(const char *file_path, unsigned long val)
@@ -86,13 +89,16 @@ 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] [-m merge_across_nodes]\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\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\n");
 
 	printf(" -a: specify the access protections of pages.\n"
 	       "     <prot> must be of the form [rwx].\n"
@@ -105,6 +111,7 @@ static void print_help(void)
 	       "     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(" -s: the size of duplicated memory area (in MiB)\n");
 
 	exit(0);
 }
@@ -407,6 +414,47 @@ static int check_ksm_numa_merge(int mapping, int prot, int timeout, bool merge_a
 	return KSFT_FAIL;
 }
 
+static int ksm_merge_time(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(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;
+}
+
 int main(int argc, char *argv[])
 {
 	int ret, opt;
@@ -418,8 +466,9 @@ int main(int argc, char *argv[])
 	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, "ha:p:l:z:m:MUZN")) != -1) {
+	while ((opt = getopt(argc, argv, "ha:p:l:z:m:s:MUZNP")) != -1) {
 		switch (opt) {
 		case 'a':
 			prot = str_to_prot(optarg);
@@ -453,6 +502,12 @@ int main(int argc, char *argv[])
 			else
 				merge_across_nodes = 1;
 			break;
+		case 's':
+			size_MB = atoi(optarg);
+			if (size_MB <= 0) {
+				printf("Size must be greater than 0\n");
+				return KSFT_FAIL;
+			}
 		case 'M':
 			break;
 		case 'U':
@@ -464,6 +519,9 @@ int main(int argc, char *argv[])
 		case 'N':
 			test_name = CHECK_KSM_NUMA_MERGE;
 			break;
+		case 'P':
+			test_name = KSM_MERGE_TIME;
+			break;
 		default:
 			return KSFT_FAIL;
 		}
@@ -505,6 +563,14 @@ int main(int argc, char *argv[])
 		ret = check_ksm_numa_merge(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(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
+				     size_MB);
+		break;
 	}
 
 	if (ksm_restore(&ksm_sysfs_old)) {