[0/2] add KSM performance tests

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. 
Both patches were developed against linux-next.

Zhansaya Bagdauletkyzy (2):
  selftests: vm: add KSM merging time test
  selftests: vm: add COW time test for KSM pages

 tools/testing/selftests/vm/ksm_tests.c | 136 ++++++++++++++++++++++++-
 1 file changed, 132 insertions(+), 4 deletions(-)

On Sun, Aug 1, 2021 at 11:43 AM Zhansaya Bagdauletkyzy
<zhansayabagdaulet@gmail.com> 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 MB/s. User must specify the size of duplicated memory area (in MB)

> before running the test.

>

> The test is run as follows: ./ksm_tests -P -s 100

> The output:

>         Total size:    100 MB

>         Total time:    0.309561 s

>         Average speed: 323 MB/s

>

> Signed-off-by: Zhansaya Bagdauletkyzy <zhansayabagdaulet@gmail.com>

> ---

>  tools/testing/selftests/vm/ksm_tests.c | 76 ++++++++++++++++++++++++--

>  1 file changed, 72 insertions(+), 4 deletions(-)

>

> diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c

> index cdeb4a028538..91c6ff496655 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_TO_B 1000000ul


We should calculate everything in true megabytes.

#define MB (1ul << 20)

Also, print in MiB/s.

>

>  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 MB)\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 MB)\n");

>

>         exit(0);

>  }

> @@ -407,6 +414,49 @@ 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;

> +       long scan_time_s, scan_time_ns;


Should be "unsigned long".

> +       int avg_speed;

No needed, see below.

> +

> +       map_size *= MB_TO_B;

> +

> +       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);


> +       scan_time_s = scan_time_ns / NSEC_PER_SEC;

> +       scan_time_ns %= NSEC_PER_SEC;

> +       avg_speed = map_size / (scan_time_s * USEC_PER_SEC + scan_time_ns / NSEC_PER_USEC);


Please remove the above three lines, and replace with bellow suggestions:

> +

> +       printf("Total size:    %lu MB\n", map_size / MB_TO_B);


printf("Total size:    %lu MiB\n", map_size / MB);

> +       printf("Total time:    %ld.%06ld s\n", scan_time_s, scan_time_ns / NSEC_PER_USEC);


printf("Total time:    %ld.%09ld s\n", scan_time_ns / NSEC_PER_SEC,
scan_time_ns % NSEC_PER_SEC));

> +       printf("Average speed: %d MB/s\n", avg_speed);


The following would give a much better precision:
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 +468,9 @@ 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 +504,12 @@ 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 +521,9 @@ 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 +565,14 @@ 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

>