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From: Ian Rogers <irogers@google.com>
Date: Wed, 14 Feb 2024 15:57:24 -0800
Message-ID: <CAP-5=fWnVFabJ8MqsnAQAC5Bbk9AQmcnTCWJNrd3RGk8Ucoe-w@mail.gmail.com>
Subject: Re: [PATCH 2/4] perf hist: Simplify hist printing logic for group events
To: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>, Jiri Olsa <jolsa@kernel.org>, 
	Adrian Hunter <adrian.hunter@intel.com>, Peter Zijlstra <peterz@infradead.org>, 
	Ingo Molnar <mingo@kernel.org>, LKML <linux-kernel@vger.kernel.org>, 
	linux-perf-users@vger.kernel.org
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On Mon, Feb 12, 2024 at 11:53=E2=80=AFPM Namhyung Kim <namhyung@kernel.org>=
 wrote:
>
> It can uses an array to save the period (or percent) values for member
> events and print them together in a loop.  This simplify the logic to
> handle missing samples in members with zero values.
>
> No functional change intended.
>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/perf/ui/hist.c | 55 +++++++++++++++++---------------------------
>  1 file changed, 21 insertions(+), 34 deletions(-)
>
> diff --git a/tools/perf/ui/hist.c b/tools/perf/ui/hist.c
> index 2bf959d08354..5f4c110d840f 100644
> --- a/tools/perf/ui/hist.c
> +++ b/tools/perf/ui/hist.c
> @@ -33,6 +33,7 @@ static int __hpp__fmt(struct perf_hpp *hpp, struct hist=
_entry *he,
>         char *buf =3D hpp->buf;
>         size_t size =3D hpp->size;
>
> +       /* print stand-alone or group leader events separately */
>         if (fmt_percent) {
>                 double percent =3D 0.0;
>                 u64 total =3D hists__total_period(hists);
> @@ -45,12 +46,19 @@ static int __hpp__fmt(struct perf_hpp *hpp, struct hi=
st_entry *he,
>                 ret =3D hpp__call_print_fn(hpp, print_fn, fmt, len, get_f=
ield(he));
>
>         if (evsel__is_group_event(evsel)) {
> -               int prev_idx, idx_delta;
> +               int idx;
>                 struct hist_entry *pair;
>                 int nr_members =3D evsel->core.nr_members;
> +               union {
> +                       u64 period;
> +                       double percent;
> +               } *val;
>
> -               prev_idx =3D evsel__group_idx(evsel);
> +               val =3D calloc(nr_members, sizeof(*val));
> +               if (val =3D=3D NULL)
> +                       return 0;

Looks good, but should this return value be negative to indicate an
error? Snprintf gives a negative result on error, its result is
sometimes returned from hpp__fmt_acc, as is this result.

Thanks,
Ian

>
> +               /* collect values in the group members */
>                 list_for_each_entry(pair, &he->pairs.head, pairs.node) {
>                         u64 period =3D get_field(pair);
>                         u64 total =3D hists__total_period(pair->hists);
> @@ -59,47 +67,26 @@ static int __hpp__fmt(struct perf_hpp *hpp, struct hi=
st_entry *he,
>                                 continue;
>
>                         evsel =3D hists_to_evsel(pair->hists);
> -                       idx_delta =3D evsel__group_idx(evsel) - prev_idx =
- 1;
> -
> -                       while (idx_delta--) {
> -                               /*
> -                                * zero-fill group members in the middle =
which
> -                                * have no sample
> -                                */
> -                               if (fmt_percent) {
> -                                       ret +=3D hpp__call_print_fn(hpp, =
print_fn,
> -                                                                 fmt, le=
n, 0.0);
> -                               } else {
> -                                       ret +=3D hpp__call_print_fn(hpp, =
print_fn,
> -                                                                 fmt, le=
n, 0ULL);
> -                               }
> -                       }
> -
> -                       if (fmt_percent) {
> -                               ret +=3D hpp__call_print_fn(hpp, print_fn=
, fmt, len,
> -                                                         100.0 * period =
/ total);
> -                       } else {
> -                               ret +=3D hpp__call_print_fn(hpp, print_fn=
, fmt,
> -                                                         len, period);
> -                       }
> +                       idx =3D evsel__group_idx(evsel);
>
> -                       prev_idx =3D evsel__group_idx(evsel);
> +                       if (fmt_percent)
> +                               val[idx].percent =3D 100.0 * period / tot=
al;
> +                       else
> +                               val[idx].period =3D period;
>                 }
>
> -               idx_delta =3D nr_members - prev_idx - 1;
> -
> -               while (idx_delta--) {
> -                       /*
> -                        * zero-fill group members at last which have no =
sample
> -                        */
> +               /* idx starts from 1 to skip the leader event */
> +               for (idx =3D 1; idx < nr_members; idx++) {
>                         if (fmt_percent) {
>                                 ret +=3D hpp__call_print_fn(hpp, print_fn=
,
> -                                                         fmt, len, 0.0);
> +                                                         fmt, len, val[i=
dx].percent);
>                         } else {
>                                 ret +=3D hpp__call_print_fn(hpp, print_fn=
,
> -                                                         fmt, len, 0ULL)=
;
> +                                                         fmt, len, val[i=
dx].period);
>                         }
>                 }
> +
> +               free(val);
>         }
>
>         /*
> --
> 2.43.0.687.g38aa6559b0-goog
>