Re: [PATCH] perf stat: Create '--add-default' option to append default list

["Jin, Yao" <yao.jin@linux.intel.com>]

Hi Arnaldo,

On 12/23/2020 12:15 AM, Arnaldo Carvalho de Melo wrote:
> Em Tue, Dec 22, 2020 at 09:11:31AM +0800, Jin Yao escreveu:
>> The event default list includes the most common events which are widely
>> used by users. But with -e option, the current perf only counts the events
>> assigned by -e option. Users may want to collect some extra events with
>> the default list. For this case, users have to manually add all the events
>> from the default list. It's inconvenient. Also, users may don't know how to
>> get the default list.
>>
>> It's better to add a new option to append default list to the -e events.
>> The new option is '--add-default'.
>>
>> Before:
>>
>> root@kbl-ppc:~# ./perf stat -e power/energy-pkg/ -a -- sleep 1
>>
>>   Performance counter stats for 'system wide':
>>
>>                2.05 Joules power/energy-pkg/
>>
>>         1.000857974 seconds time elapsed
>>
>> After:
>>
>> root@kbl-ppc:~# ./perf stat -e power/energy-pkg/ -a --add-default -- sleep 1
> 
> I thought about:
> 
>      perf stat -e +power/energy-pkg/ -a -- sleep 1
> 

I was surprised to see that '+<event>' syntax had been supported.

root@kbl-ppc:~# ./perf stat -e +power/energy-pkg/ -a -- sleep 1

  Performance counter stats for 'system wide':

               1.99 Joules +power/energy-pkg/

        1.000877852 seconds time elapsed

root@kbl-ppc:~# ./perf stat -e +power/energy-pkg/,+cycles -a -- sleep 1

  Performance counter stats for 'system wide':

               2.00 Joules +power/energy-pkg/
         13,780,620        +cycles

        1.001639147 seconds time elapsed

Are there any scripts or usages need the prefix '+' before event? I don't know. But if we append the 
'+<event>' to the default event list, will break something potentially?

> Which would have its counterpart:
> 
>      perf stat -e -cycles -0a --sleep 1
> 
> To remove an event from the defaults, perhaps to deal with some specific
> hardware where the default or what is in -d, -dd, -ddd, etc can't all be
> counted. I.e. - and + would remove or add from whaver list was there at
> that point.
> 
> - Arnaldo
>   

Yes, + and - are more flexible solution. Just for above question, will '+<event>' break existing 
usage? And for '-', I don't know if user can remember clearly for what the events are in default list.

Thanks
Jin Yao

>>   Performance counter stats for 'system wide':
>>
>>                2.10 Joules power/energy-pkg/         #    0.000 K/sec
>>            8,009.89 msec   cpu-clock                 #    7.995 CPUs utilized
>>                 140        context-switches          #    0.017 K/sec
>>                   9        cpu-migrations            #    0.001 K/sec
>>                  66        page-faults               #    0.008 K/sec
>>          10,671,929        cycles                    #    0.001 GHz
>>           4,736,880        instructions              #    0.44  insn per cycle
>>             942,951        branches                  #    0.118 M/sec
>>              76,096        branch-misses             #    8.07% of all branches
>>
>>         1.001809960 seconds time elapsed
>>
>> Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
>> ---
>>   tools/perf/Documentation/perf-stat.txt | 5 +++++
>>   tools/perf/builtin-stat.c              | 4 +++-
>>   tools/perf/util/stat.h                 | 1 +
>>   3 files changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
>> index 5d4a673d7621..75a83c2e4dc5 100644
>> --- a/tools/perf/Documentation/perf-stat.txt
>> +++ b/tools/perf/Documentation/perf-stat.txt
>> @@ -438,6 +438,11 @@ convenient for post processing.
>>   --summary::
>>   Print summary for interval mode (-I).
>>   
>> +--add-default::
>> +The default event list includes the most common events which are widely
>> +used by users. But with -e option, the perf only counts the events assigned
>> +by -e option. This options appends the default event list to the -e events.
>> +
>>   EXAMPLES
>>   --------
>>   
>> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
>> index 89c32692f40c..6ac7b946f9a7 100644
>> --- a/tools/perf/builtin-stat.c
>> +++ b/tools/perf/builtin-stat.c
>> @@ -1173,6 +1173,8 @@ static struct option stat_options[] = {
>>   		       "print summary for interval mode"),
>>   	OPT_BOOLEAN(0, "quiet", &stat_config.quiet,
>>   			"don't print output (useful with record)"),
>> +	OPT_BOOLEAN(0, "add-default", &stat_config.add_default,
>> +		       "add default events"),
>>   #ifdef HAVE_LIBPFM
>>   	OPT_CALLBACK(0, "pfm-events", &evsel_list, "event",
>>   		"libpfm4 event selector. use 'perf list' to list available events",
>> @@ -1755,7 +1757,7 @@ static int add_default_attributes(void)
>>   		free(str);
>>   	}
>>   
>> -	if (!evsel_list->core.nr_entries) {
>> +	if (!evsel_list->core.nr_entries || stat_config.add_default) {
>>   		if (target__has_cpu(&target))
>>   			default_attrs0[0].config = PERF_COUNT_SW_CPU_CLOCK;
>>   
>> diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
>> index 9979b4b100f2..6ccc6936348c 100644
>> --- a/tools/perf/util/stat.h
>> +++ b/tools/perf/util/stat.h
>> @@ -123,6 +123,7 @@ struct perf_stat_config {
>>   	bool			 metric_no_merge;
>>   	bool			 stop_read_counter;
>>   	bool			 quiet;
>> +	bool			 add_default;
>>   	FILE			*output;
>>   	unsigned int		 interval;
>>   	unsigned int		 timeout;
>> -- 
>> 2.17.1
>>
>