Re: [PATCH 2/3] perf test: Fix record tests on Intel Broadwell

[Ian Rogers]

On Wed, Sep 23, 2026 at 2:53 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> I noticed it failed for leader sampling tests on Broadwell.  It's
> because the period of groups members are a little bit different.  Maybe
> there's an hardware issue but anyway it's close enough to treat them as
> same.  I printed the value like below.
>
>   $ perf test record
>   ...
>   prev: 462507, curr: 462506
>   prev: 494783, curr: 494782
>   prev: 454350, curr: 454349
>   prev: 502782, curr: 502781
>   prev: 566693, curr: 566692
>   prev: 606558, curr: 606557
>   prev: 559770, curr: 559769
>   prev: 595737, curr: 595736
>   prev: 643386, curr: 643385
>   prev: 663672, curr: 663671
>   prev: 620622, curr: 620621
>   prev: 650419, curr: 650418
>   Leader sampling [Failed inconsistent cycles count]
>
> Let's update the logic to compare values to allow 1% of errors.
>
> Also I think it should compare only if sees the non-leader samples so
> split the check of (($index % 2)).
>
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>

+Dapeng Mi

Tested-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/tests/shell/record.sh | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/tests/shell/record.sh b/tools/perf/tests/shell/record.sh
> index cf8ba3d3411b0bcc..04df35b30b0c15fd 100755
> --- a/tools/perf/tests/shell/record.sh
> +++ b/tools/perf/tests/shell/record.sh
> @@ -550,11 +550,14 @@ test_leader_sampling() {
>    while IFS= read -r line
>    do
>      cycles=$(echo $line | awk '{for(i=1;i<=NF;i++) if($i=="cycles:") print $(i-1)}')
> -    if [ $(($index%2)) -ne 0 ] && [ ${cycles}x != ${prev_cycles}x ]
> +    if [ $(($index%2)) -ne 0 ]
>      then
> -      invalid_counts=$(($invalid_counts+1))
> -    else
> -      valid_counts=$(($valid_counts+1))
> +      if (( $(bc <<< "scale=4; r = ${cycles} / ${prev_cycles}; r >= 0.99 && r <= 1.01") ))
> +      then
> +        valid_counts=$(($valid_counts+1))
> +      else
> +        invalid_counts=$(($invalid_counts+1))
> +      fi
>      fi
>      index=$(($index+1))
>      prev_cycles=$cycles
> --
> 2.56.0.rc1.310.g51773c2048-goog
>