Re: [PATCH v1 4/9] perf list: Generalize limiting to a PMU name

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

On 2022-11-14 9:02 a.m., Ian Rogers wrote:
> On Mon, Nov 14, 2022 at 5:58 AM Liang, Kan <kan.liang@linux.intel.com> wrote:
>>
>>
>>
>> On 2022-11-14 2:51 a.m., Ian Rogers wrote:
>>> Deprecate the --cputype option and add a --unit option where '--unit
>>> cpu_atom' behaves like '--cputype atom'. The --unit option can be used
>>> with arbitrary PMUs, for example:
>>>
>>> ```
>>> $ perf list --unit msr pmu
>>>
>>> List of pre-defined events (to be used in -e or -M):
>>>
>>>   msr/aperf/                                         [Kernel PMU event]
>>>   msr/cpu_thermal_margin/                            [Kernel PMU event]
>>>   msr/mperf/                                         [Kernel PMU event]
>>>   msr/pperf/                                         [Kernel PMU event]
>>>   msr/smi/                                           [Kernel PMU event]
>>>   msr/tsc/                                           [Kernel PMU event]
>>> ```
>>>
>>> Signed-off-by: Ian Rogers <irogers@google.com>
>>> ---
>>>  tools/perf/Documentation/perf-list.txt |  6 +++---
>>>  tools/perf/builtin-list.c              | 18 ++++++++++++------
>>>  tools/perf/util/metricgroup.c          |  3 ++-
>>>  tools/perf/util/pmu.c                  |  4 +---
>>>  4 files changed, 18 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/tools/perf/Documentation/perf-list.txt b/tools/perf/Documentation/perf-list.txt
>>> index 57384a97c04f..44a819af573d 100644
>>> --- a/tools/perf/Documentation/perf-list.txt
>>> +++ b/tools/perf/Documentation/perf-list.txt
>>> @@ -39,9 +39,9 @@ any extra expressions computed by perf stat.
>>>  --deprecated::
>>>  Print deprecated events. By default the deprecated events are hidden.
>>>
>>> ---cputype::
>>> -Print events applying cpu with this type for hybrid platform
>>> -(e.g. --cputype core or --cputype atom)
>>
>> The "--cputype" is removed from the documentation, but the code is still
>> available. It sounds weird.
>>
>> Can we still keep the "--cputype" in the documentation? Just say that
>> it's a deprecated option, please use the --unit cpu_atom instead. I
>> think even better if we can throw a warning and point to --unit when the
>> "--cputype" is used.
> 
> I think we want to remove --cputype widely in the code and replace
> what it does with specifying a PMU name. Advertising a flag but then
> warning seems strange and is a behavioral change from what is
> currently done. For raw-dump we don't document it in the man page and
> hide the flag, this is the pattern being followed here.

I see. So the --cputype is still supported, but only be hidden in the
default. Sure, we can follow the pattern.

> 
> Thanks,
> Ian
> 
>> Thanks,
>> Kan
>>> +--unit::
>>> +Print PMU events and metrics limited to the specific PMU name.
>>> +(e.g. --unit cpu, --unit msr, --unit cpu_core, --unit cpu_atom)
>>>
>>>  [[EVENT_MODIFIERS]]
>>>  EVENT MODIFIERS
>>> diff --git a/tools/perf/builtin-list.c b/tools/perf/builtin-list.c
>>> index 58e1ec1654ef..cc84ced6da26 100644
>>> --- a/tools/perf/builtin-list.c
>>> +++ b/tools/perf/builtin-list.c
>>> @@ -21,7 +21,6 @@
>>>
>>>  static bool desc_flag = true;
>>>  static bool details_flag;
>>> -static const char *hybrid_type;
>>>
>>>  int cmd_list(int argc, const char **argv)
>>>  {
>>> @@ -30,6 +29,8 @@ int cmd_list(int argc, const char **argv)
>>>       bool long_desc_flag = false;
>>>       bool deprecated = false;
>>>       char *pmu_name = NULL;
>>> +     const char *hybrid_name = NULL;
>>> +     const char *unit_name = NULL;
>>>       struct option list_options[] = {
>>>               OPT_BOOLEAN(0, "raw-dump", &raw_dump, "Dump raw events"),
>>>               OPT_BOOLEAN('d', "desc", &desc_flag,
>>> @@ -40,9 +41,10 @@ int cmd_list(int argc, const char **argv)
>>>                           "Print information on the perf event names and expressions used internally by events."),
>>>               OPT_BOOLEAN(0, "deprecated", &deprecated,
>>>                           "Print deprecated events."),
>>> -             OPT_STRING(0, "cputype", &hybrid_type, "hybrid cpu type",
>>> -                        "Print events applying cpu with this type for hybrid platform "
>>> -                        "(e.g. core or atom)"),
>>> +             OPT_STRING(0, "cputype", &hybrid_name, "hybrid cpu type",
>>> +                        "Limit PMU or metric printing to the given hybrid PMU (e.g. core or atom)."),
>>> +             OPT_STRING(0, "unit", &unit_name, "PMU name",
>>> +                        "Limit PMU or metric printing to the specified PMU."),
>>>               OPT_INCR(0, "debug", &verbose,
>>>                            "Enable debugging output"),
>>>               OPT_END()
>>> @@ -53,6 +55,8 @@ int cmd_list(int argc, const char **argv)
>>>       };
>>>
>>>       set_option_flag(list_options, 0, "raw-dump", PARSE_OPT_HIDDEN);
>>> +     /* Hide hybrid flag for the more generic 'unit' flag. */
>>> +     set_option_flag(list_options, 0, "cputype", PARSE_OPT_HIDDEN);
>>>
>>>       argc = parse_options(argc, argv, list_options, list_usage,
>>>                            PARSE_OPT_STOP_AT_NON_OPTION);
>>> @@ -62,8 +66,10 @@ int cmd_list(int argc, const char **argv)
>>>       if (!raw_dump && pager_in_use())
>>>               printf("\nList of pre-defined events (to be used in -e or -M):\n\n");
>>>
>>> -     if (hybrid_type) {
>>> -             pmu_name = perf_pmu__hybrid_type_to_pmu(hybrid_type);
>>> +     if (unit_name)
>>> +             pmu_name = strdup(unit_name);
>>> +     else if (hybrid_name) {
>>> +             pmu_name = perf_pmu__hybrid_type_to_pmu(hybrid_name);
>>>               if (!pmu_name)
>>>                       pr_warning("WARNING: hybrid cputype is not supported!\n");
>>>       }

Can the tool implicitly convert the --cputype to --unit at the very
beginning? (Just need to append a prefix "cpu_".). Here we only need to
handle the unit_name.
The same logic may be applied for other tools if someone implements the
--unit for the stat or record later.

BTW: we may want to check the existence of a PMU here, just like what we
did for the hybrid. If a user perf list a nonexistence PMU, we can warn
here.

Thanks,
Kan

>>> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
>>> index 4c98ac29ee13..1943fed9b6d9 100644
>>> --- a/tools/perf/util/metricgroup.c
>>> +++ b/tools/perf/util/metricgroup.c
>>> @@ -556,11 +556,12 @@ static int metricgroup__print_callback(const struct pmu_event *pe,
>>>                                      void *vdata)
>>>  {
>>>       struct metricgroup_print_data *data = vdata;
>>> +     const char *pmu = pe->pmu ?: "cpu";
>>>
>>>       if (!pe->metric_expr)
>>>               return 0;
>>>
>>> -     if (data->pmu_name && perf_pmu__is_hybrid(pe->pmu) && strcmp(data->pmu_name, pe->pmu))
>>> +     if (data->pmu_name && strcmp(data->pmu_name, pmu))
>>>               return 0;
>>>
>>>       return metricgroup__print_pmu_event(pe, data->metricgroups, data->filter,
>>> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
>>> index a8f9f47c6ed9..9c771f136b81 100644
>>> --- a/tools/perf/util/pmu.c
>>> +++ b/tools/perf/util/pmu.c
>>> @@ -1694,10 +1694,8 @@ void print_pmu_events(const char *event_glob, bool name_only, bool quiet_flag,
>>>       pmu = NULL;
>>>       j = 0;
>>>       while ((pmu = perf_pmu__scan(pmu)) != NULL) {
>>> -             if (pmu_name && perf_pmu__is_hybrid(pmu->name) &&
>>> -                 strcmp(pmu_name, pmu->name)) {
>>> +             if (pmu_name && pmu->name && strcmp(pmu_name, pmu->name))
>>>                       continue;
>>> -             }
>>>
>>>               list_for_each_entry(alias, &pmu->aliases, list) {
>>>                       char *name = alias->desc ? alias->name :