Re: [PATCH v3 1/2] selftests: vm: add KSM merging time test

[Tyler Hicks <tyhicks@linux.microsoft.com>]

On 2021-08-19 21:33:41, Zhansaya Bagdauletkyzy wrote:
> 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
> 
> Signed-off-by: Zhansaya Bagdauletkyzy <zhansayabagdaulet@gmail.com>
> ---
> v2 -> v3:
>  - no changes

There were no changes to this patch since v2 so my previous review still
stands:

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

Tyler

> 
> v1 -> v2:
>  As suggested by Pavel,
>  - replace MB with MiB
>  - measure speed more accurately
> 
> Pavel's comments: https://lkml.org/lkml/2021/8/3/1362 
> 
>  tools/testing/selftests/vm/ksm_tests.c | 74 ++++++++++++++++++++++++--
>  1 file changed, 70 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
> index cdeb4a028538..432dfe615e50 100644
> --- a/tools/testing/selftests/vm/ksm_tests.c
> +++ b/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)) {
> -- 
> 2.25.1
>