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Re: [PATCH 1/3] benchtests: Fix walking sizes and directions for *-walk benchmarks
... and now pushed.
Siddhesh
On Thursday 09 November 2017 10:43 AM, Siddhesh Poyarekar wrote:
> Make the walking benchmarks walk only backwards since copying both
> ways is biased in favour of implementations that use non-temporal
> stores for larger sizes; falkor is one of them. This also fixes up
> bugs in computation of the result which ended up multiplying the
> length with the timing result unnecessarily.
>
> * benchtests/bench-memcpy-walk.c (do_one_test): Copy only
> backwards. Fix timing computation.
> * benchtests/bench-memmove-walk.c (do_one_test): Likewise.
> * benchtests/bench-memset-walk.c (do_one_test): Walk backwards
> on memset by N at a time. Fix timing computation.
> ---
> benchtests/bench-memcpy-walk.c | 14 +++++---------
> benchtests/bench-memmove-walk.c | 15 +++++----------
> benchtests/bench-memset-walk.c | 4 ++--
> 3 files changed, 12 insertions(+), 21 deletions(-)
>
> diff --git a/benchtests/bench-memcpy-walk.c b/benchtests/bench-memcpy-walk.c
> index 69d467d..5b56341 100644
> --- a/benchtests/bench-memcpy-walk.c
> +++ b/benchtests/bench-memcpy-walk.c
> @@ -47,26 +47,22 @@ static void
> do_one_test (json_ctx_t *json_ctx, impl_t *impl, char *dst, char *src,
> size_t len)
> {
> - size_t i, iters = MIN_PAGE_SIZE / len;
> + size_t i = 0;
> timing_t start, stop, cur;
>
> char *dst_end = dst + MIN_PAGE_SIZE - len;
> char *src_end = src + MIN_PAGE_SIZE - len;
>
> TIMING_NOW (start);
> - /* Copy the entire buffer back and forth, LEN at a time. */
> - for (i = 0; i < iters && dst_end >= dst && src <= src_end; src++, dst_end--)
> - {
> - CALL (impl, dst_end, src, len);
> - CALL (impl, src, dst_end, len);
> - i += 2;
> - }
> + /* Copy the entire buffer backwards, LEN at a time. */
> + for (; src_end >= src && dst_end >= dst; src_end -= len, dst_end -= len, i++)
> + CALL (impl, src_end, dst_end, len);
> TIMING_NOW (stop);
>
> TIMING_DIFF (cur, start, stop);
>
> /* Get time taken per function call. */
> - json_element_double (json_ctx, (double) cur * len / i);
> + json_element_double (json_ctx, (double) cur / i);
> }
>
> static void
> diff --git a/benchtests/bench-memmove-walk.c b/benchtests/bench-memmove-walk.c
> index 54dcd64..969ddd9 100644
> --- a/benchtests/bench-memmove-walk.c
> +++ b/benchtests/bench-memmove-walk.c
> @@ -47,26 +47,22 @@ static void
> do_one_test (json_ctx_t *json_ctx, impl_t *impl, char *dst, char *src,
> size_t len)
> {
> - size_t i, iters = MIN_PAGE_SIZE / len;
> + size_t i = 0;
> timing_t start, stop, cur;
>
> char *dst_end = dst + MIN_PAGE_SIZE - len;
> char *src_end = src + MIN_PAGE_SIZE - len;
>
> TIMING_NOW (start);
> - /* Copy the entire buffer back and forth, LEN at a time. */
> - for (i = 0; i < iters && dst_end >= dst && src <= src_end; src++, dst_end--)
> - {
> - CALL (impl, dst_end, src, len);
> - CALL (impl, src, dst_end, len);
> - i += 2;
> - }
> + /* Copy the entire buffer backwards, LEN at a time. */
> + for (; src_end >= src && dst <= dst_end; dst += len, src_end -= len, i++)
> + CALL (impl, dst, src_end, len);
> TIMING_NOW (stop);
>
> TIMING_DIFF (cur, start, stop);
>
> /* Get time taken per function call. */
> - json_element_double (json_ctx, (double) cur * len / i);
> + json_element_double (json_ctx, (double) cur / i);
> }
>
> static void
> @@ -79,7 +75,6 @@ do_test (json_ctx_t *json_ctx, size_t len, bool overlap)
> if (overlap)
> buf2 = buf1;
>
> - /* First the non-overlapping moves. */
> FOR_EACH_IMPL (impl, 0)
> do_one_test (json_ctx, impl, (char *) buf2, (char *) buf1, len);
>
> diff --git a/benchtests/bench-memset-walk.c b/benchtests/bench-memset-walk.c
> index 59d2626..80fbe09 100644
> --- a/benchtests/bench-memset-walk.c
> +++ b/benchtests/bench-memset-walk.c
> @@ -66,14 +66,14 @@ do_one_test (json_ctx_t *json_ctx, impl_t *impl, CHAR *s, CHAR *s_end,
> timing_t start, stop, cur;
>
> TIMING_NOW (start);
> - for (i = 0; i < iters && s <= s_end; s++, i++)
> + for (i = 0; i < iters && s <= s_end; s_end -= n, i++)
> CALL (impl, s, c, n);
> TIMING_NOW (stop);
>
> TIMING_DIFF (cur, start, stop);
>
> /* Get time taken per function call. */
> - json_element_double (json_ctx, (double) cur * n / i);
> + json_element_double (json_ctx, (double) cur / i);
> }
>
> static void
>