Commit 5036880e authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

selftests/vm: add test to measure MADV_UNMERGEABLE performance 

Let's add a test to measure performance of KSM breaking not triggered via
COW, but triggered by disabling KSM on an area filled with KSM pages via
MADV_UNMERGEABLE.

Link: https://lkml.kernel.org/r/20221021101141.84170-2-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Acked-by: default avatarPeter Xu <peterx@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent c31783ee

tools/testing/selftests/vm/ksm_tests.c

+74 −2
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ enum ksm_test_name { 
	CHECK_KSM_NUMA_MERGE,

	KSM_MERGE_TIME,

	KSM_MERGE_TIME_HUGE_PAGES,

	KSM_UNMERGE_TIME,

	KSM_COW_TIME

};
@@ -111,6 +112,9 @@ static void print_help(void) 
	       " -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"

	       " -D evaluate unmerging time and speed when disabling KSM.\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"
@@ -188,6 +192,16 @@ static int ksm_merge_pages(void *addr, size_t size, struct timespec start_time, 
	return 0;

}



static int ksm_unmerge_pages(void *addr, size_t size,

			     struct timespec start_time, int timeout)

{

	if (madvise(addr, size, MADV_UNMERGEABLE)) {

		perror("madvise");

		return 1;

	}

	return 0;

}



static bool assert_ksm_pages_count(long dupl_page_count)

{

	unsigned long max_page_sharing, pages_sharing, pages_shared;
@@ -560,6 +574,53 @@ static int ksm_merge_time(int mapping, int prot, int timeout, size_t map_size) 
	return KSFT_FAIL;

}



static int ksm_unmerge_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, &start_time)) {

		perror("clock_gettime");

		goto err_out;

	}

	if (ksm_unmerge_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;

}



static int ksm_cow_time(int mapping, int prot, int timeout, size_t page_size)

{

	void *map_ptr;
@@ -644,7 +705,7 @@ 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:MUZNPCH")) != -1) {

	while ((opt = getopt(argc, argv, "ha:p:l:z:m:s:MUZNPCHD")) != -1) {

		switch (opt) {

		case 'a':

			prot = str_to_prot(optarg);
@@ -701,6 +762,9 @@ int main(int argc, char *argv[]) 
		case 'H':

			test_name = KSM_MERGE_TIME_HUGE_PAGES;

			break;

		case 'D':

			test_name = KSM_UNMERGE_TIME;

			break;

		case 'C':

			test_name = KSM_COW_TIME;

			break;
@@ -762,6 +826,14 @@ int main(int argc, char *argv[]) 
		ret = ksm_merge_hugepages_time(MAP_PRIVATE | MAP_ANONYMOUS, prot,

				ksm_scan_limit_sec, size_MB);

		break;

	case KSM_UNMERGE_TIME:

		if (size_MB == 0) {

			printf("Option '-s' is required.\n");

			return KSFT_FAIL;

		}

		ret = ksm_unmerge_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);