Re: [PATCH 3/5] benchtests: Add partial overlap case in bench-memmove-walk.c

["H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org>]

On Tue, Aug 24, 2021 at 1:28 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> This commit adds a new partial overlap benchmark. This is generally
> the most interesting performance case for memmove and was missing.
> ---
>  benchtests/bench-memmove-walk.c | 67 ++++++++++++++++++++++++---------
>  1 file changed, 49 insertions(+), 18 deletions(-)
>
> diff --git a/benchtests/bench-memmove-walk.c b/benchtests/bench-memmove-walk.c
> index b5fdb2a422..18b716f5cb 100644
> --- a/benchtests/bench-memmove-walk.c
> +++ b/benchtests/bench-memmove-walk.c
> @@ -36,6 +36,10 @@
>  # define TIMEOUT (20 * 60)
>  # include "bench-string.h"
>
> +#define NO_OVERLAP 0
> +#define PARTIAL_OVERLAP 1
> +#define COMPLETE_OVERLAP 2
> +
>  IMPL (memmove, 1)
>  #endif
>
> @@ -66,20 +70,40 @@ do_one_test (json_ctx_t *json_ctx, impl_t *impl, char *dst, char *src,
>  }
>
>  static void
> -do_test (json_ctx_t *json_ctx, size_t len, bool overlap)
> +do_test (json_ctx_t *json_ctx, size_t len, int overlap, int both_ways)
>  {
> -  json_element_object_begin (json_ctx);
> -  json_attr_uint (json_ctx, "length", (double) len);
> -  json_array_begin (json_ctx, "timings");
> -
> -  if (overlap)
> -    buf2 = buf1;
> -
> -  FOR_EACH_IMPL (impl, 0)
> -    do_one_test (json_ctx, impl, (char *) buf2, (char *) buf1, len);
> -
> -  json_array_end (json_ctx);
> -  json_element_object_end (json_ctx);
> +  char *s1, *s2, *tmp;
> +  size_t repeats;
> +
> +  s1 = (char *) (buf1);
> +  s2 = (char *) (buf2);
> +  if (overlap != NO_OVERLAP)
> +    s2 = s1;
> +  if (overlap == PARTIAL_OVERLAP)
> +    s2 += len / 2;
> +
> +  for (repeats = both_ways ? 2 : 1; repeats; --repeats)
> +    {
> +      json_element_object_begin (json_ctx);
> +      json_attr_uint (json_ctx, "length", (double) len);
> +      json_attr_string(json_ctx, "overlap",
> +                       overlap == NO_OVERLAP        ? "none"
> +                       : overlap == PARTIAL_OVERLAP ? "partial"
> +                                                    : "complete");
> +      json_attr_uint (json_ctx, "dst > src", (double) (s2 > s1));
> +      json_array_begin (json_ctx, "timings");
> +
> +
> +      FOR_EACH_IMPL (impl, 0)
> +        do_one_test (json_ctx, impl, (char *) buf2, (char *) buf1, len);
> +
> +      json_array_end (json_ctx);
> +      json_element_object_end (json_ctx);
> +
> +      tmp = s1;
> +      s1 = s2;
> +      s2 = tmp;
> +    }
>  }
>
>  int
> @@ -107,15 +131,22 @@ test_main (void)
>    /* Non-overlapping buffers.  */
>    for (size_t i = START_SIZE; i <= MIN_PAGE_SIZE; i <<= 1)
>      {
> -      do_test (&json_ctx, i, false);
> -      do_test (&json_ctx, i + 1, false);
> +      do_test (&json_ctx, i, NO_OVERLAP, 1);
> +      do_test (&json_ctx, i + 1, NO_OVERLAP, 1);
> +    }
> +
> +  /* Partially-overlapping buffers.  */
> +  for (size_t i = START_SIZE; i <= MIN_PAGE_SIZE / 2; i <<= 1)
> +    {
> +      do_test (&json_ctx, i, PARTIAL_OVERLAP, 1);
> +      do_test (&json_ctx, i + 1, PARTIAL_OVERLAP, 1);
>      }
>
> -  /* Overlapping buffers.  */
> +  /* Complete-overlapping buffers.  */
>    for (size_t i = START_SIZE; i <= MIN_PAGE_SIZE; i <<= 1)
>      {
> -      do_test (&json_ctx, i, true);
> -      do_test (&json_ctx, i + 1, true);
> +      do_test (&json_ctx, i, COMPLETE_OVERLAP, 0);
> +      do_test (&json_ctx, i + 1, COMPLETE_OVERLAP, 0);
>      }
>
>    json_array_end (&json_ctx);
> --
> 2.25.1
>

LGTM.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

Thanks.

-- 
H.J.