Re: [PATCH v1] perf metrics: Remove the "No_group" metric group

["Liang, Kan" <kan.liang@linux.intel.com>]

On 2024-04-03 2:31 p.m., Ian Rogers wrote:
> On Wed, Apr 3, 2024 at 10:59 AM Liang, Kan <kan.liang@linux.intel.com> wrote:
>>
>>
>>
>> On 2024-04-03 12:46 p.m., Ian Rogers wrote:
>>> Rather than place metrics without a metric group in "No_group" place
>>> them in a a metric group that is their name. Still allow such metrics
>>> to be selected if "No_group" is passed, this change just impacts perf
>>> list.
>>
>> So it looks like the "No_group" is not completely removed.
>> They are just not seen in the perf list, but users can still use it via
>> perf stat -M No_group, right?
>>
>> If so, why we want to remove it from perf list? Where can the end user
>> know which metrics are included in the No_group?
>>
>> If the No_group is useless, why not completely remove it?
> 
> Agreed. For command line argument deprecation we usually keep the
> option but hide it from help with PARSE_OPT_HIDDEN, so I was trying to
> follow that pattern albeit that a metric group isn't a command line
> option it's an option to an option.
>

Perf list has a deprecated option to show the deprecated events.
The "No_group" should be a deprecated metrics group.

If so, to follow the same pattern, I think perf list should still
display the "No_group" with the --deprecated option at least.

Thanks,
Kan

> Thanks,
> Ian
> 
>> Thanks,
>> Kan
>>
>>>
>>> Signed-off-by: Ian Rogers <irogers@google.com>
>>> ---
>>>  tools/perf/util/metricgroup.c | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
>>> index 79ef6095ab28..6ec083af14a1 100644
>>> --- a/tools/perf/util/metricgroup.c
>>> +++ b/tools/perf/util/metricgroup.c
>>> @@ -455,7 +455,7 @@ static int metricgroup__add_to_mep_groups(const struct pmu_metric *pm,
>>>       const char *g;
>>>       char *omg, *mg;
>>>
>>> -     mg = strdup(pm->metric_group ?: "No_group");
>>> +     mg = strdup(pm->metric_group ?: pm->metric_name);
>>>       if (!mg)
>>>               return -ENOMEM;
>>>       omg = mg;
>>> @@ -466,7 +466,7 @@ static int metricgroup__add_to_mep_groups(const struct pmu_metric *pm,
>>>               if (strlen(g))
>>>                       me = mep_lookup(groups, g, pm->metric_name);
>>>               else
>>> -                     me = mep_lookup(groups, "No_group", pm->metric_name);
>>> +                     me = mep_lookup(groups, pm->metric_name, pm->metric_name);
>>>
>>>               if (me) {
>>>                       me->metric_desc = pm->desc;