Re: [PATCH 2/2] perf test: Skip metrics w/o event name in stat STD output linter

[Ian Rogers]

On Fri, Jun 23, 2023 at 4:01 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> This test checks if the output of perf stat to match event names and
> metrics.  So it wants the output lines to have both event name and
> metric.  Otherwise it should skip the line.
>
> On AMD machines, the instruction event has two metrics and they are printed
> in separate lines.  It makes the line without event name like below:
>
>   # perf stat -a sleep 1
>
>    Performance counter stats for 'system wide':
>
>            64,383.34 msec cpu-clock                  #   64.048 CPUs utilized
>               14,526      context-switches           #  225.617 /sec
>                  112      cpu-migrations             #    1.740 /sec
>                  190      page-faults                #    2.951 /sec
>          807,558,652      cycles                     #    0.013 GHz                         (83.30%)
>           69,809,799      stalled-cycles-frontend    #    8.64% frontend cycles idle        (83.30%)
>          196,983,266      stalled-cycles-backend     #   24.39% backend cycles idle         (83.30%)
>          424,876,008      instructions               #    0.53  insn per cycle
>  (here) --->                                  #    0.46  stalled cycles per insn     (83.30%)
>           97,788,321      branches                   #    1.519 M/sec                       (83.34%)
>            4,147,377      branch-misses              #    4.24% of all branches             (83.46%)
>
>          1.005241409 seconds time elapsed
>
> Also modern Intel machines have TopDown metrics which also don't have
> event names.
>
>   # perf stat -a sleep 1
>
>    Performance counter stats for 'system wide':
>
>             8,015.39 msec cpu-clock                        #    7.996 CPUs utilized
>                5,823      context-switches                 #  726.477 /sec
>                  189      cpu-migrations                   #   23.580 /sec
>                  139      page-faults                      #   17.342 /sec
>          435,139,308      cycles                           #    0.054 GHz
>          193,891,345      instructions                     #    0.45  insn per cycle
>           42,773,028      branches                         #    5.336 M/sec
>            2,298,113      branch-misses                    #    5.37% of all branches
>                           TopdownL1                 #     25.5 %  tma_backend_bound
>               /-->                                  #      7.9 %  tma_bad_speculation
>     (here) --+                                      #     55.7 %  tma_frontend_bound
>               \-->                                  #     10.9 %  tma_retiring
>
>          1.002395924 seconds time elapsed
>
> There is a check to skip TopdownL1 and TopdownL2 specifically but it
> does not cover every affected lines.
>
> So there is another check to skip the line if it has nothing on the left
> side of # sign.  Well.. it seems ok but that's not enough too.
>
> When aggregation mode (like --per-socket or --per-thread) is used, it
> adds some prefix (e.g. CPU socket, task name and PID) in the output
> line.  So the test code ignores them to normalize result.
>
> A problem can happen for per-thread mode when task name contains one or
> more spaces.  It'd only ignore the first part of the task name, and it
> thinks there's something more in the line so it would not skip.
>
>   # perf stat -a --perf-thread sleep 1
>   ...
>             perf-21276                  #     70.2 %  tma_backend_bound
>             perf-21276                  #      3.9 %  tma_bad_speculation
>             perf-21276                  #     10.5 %  tma_frontend_bound
>             perf-21276                  #     15.3 %  tma_retiring
>             ^^^^^^^^^^
>             (ignored)
>
>          my task-21328                  #     70.2 %  tma_backend_bound
>          my task-21328                  #      3.9 %  tma_bad_speculation
>          my task-21328                  #     10.5 %  tma_frontend_bound
>          my task-21328                  #     15.3 %  tma_retiring
>          ^^
>      (ignored)
>
> So I think it should look at the metric names instead.  Add skip_metric
> to hold the list of names to skip.  It would contain 'stalled cycles per
> insn' and metrics started by 'tma_'.
>
> Fixes: 99a04a48f225 ("perf test: Add test case for the standard 'perf stat' output")
> Cc: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>

Acked-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/tests/shell/stat+std_output.sh | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/tools/perf/tests/shell/stat+std_output.sh b/tools/perf/tests/shell/stat+std_output.sh
> index 1f70aab45184..f972b31fa0c2 100755
> --- a/tools/perf/tests/shell/stat+std_output.sh
> +++ b/tools/perf/tests/shell/stat+std_output.sh
> @@ -12,8 +12,7 @@ stat_output=$(mktemp /tmp/__perf_test.stat_output.std.XXXXX)
>
>  event_name=(cpu-clock task-clock context-switches cpu-migrations page-faults stalled-cycles-frontend stalled-cycles-backend cycles instructions branches branch-misses)
>  event_metric=("CPUs utilized" "CPUs utilized" "/sec" "/sec" "/sec" "frontend cycles idle" "backend cycles idle" "GHz" "insn per cycle" "/sec" "of all branches")
> -
> -metricgroup_name=(TopdownL1 TopdownL2)
> +skip_metric=("stalled cycles per insn" "tma_")
>
>  cleanup() {
>    rm -f "${stat_output}"
> @@ -58,13 +57,14 @@ function commachecker()
>
>                 main_body=$(echo $line | cut -d' ' -f$prefix-)
>                 x=${main_body%#*}
> -               # Check default metricgroup
> -               y=$(echo $x | tr -d ' ')
> -               [ "$y" = "" ] && continue
> -               for i in "${!metricgroup_name[@]}"; do
> -                       [[ "$y" == *"${metricgroup_name[$i]}"* ]] && break
> +               [ "$x" = "" ] && continue
> +
> +               # Skip metrics without event name
> +               y=${main_body#*#}
> +               for i in "${!skip_metric[@]}"; do
> +                       [[ "$y" == *"${skip_metric[$i]}"* ]] && break
>                 done
> -               [[ "$y" == *"${metricgroup_name[$i]}"* ]] && continue
> +               [[ "$y" == *"${skip_metric[$i]}"* ]] && continue
>
>                 # Check default event
>                 for i in "${!event_name[@]}"; do
> --
> 2.41.0.162.gfafddb0af9-goog
>