linux-kernel - Re: [PATCH v4 3/4] perf-stat: introduce config stat.bpf-counter-events

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Date:   Sun, 25 Apr 2021 19:09:07 +0000
From:   Song Liu <songliubraving@...com>
To:     Jiri Olsa <jolsa@...hat.com>
CC:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Song Liu <song@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Kernel Team <Kernel-team@...com>,
        "acme@...hat.com" <acme@...hat.com>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "jolsa@...nel.org" <jolsa@...nel.org>
Subject: Re: [PATCH v4 3/4] perf-stat: introduce config
 stat.bpf-counter-events



> On Apr 25, 2021, at 8:16 AM, Jiri Olsa <jolsa@...hat.com> wrote:
> 
> On Sun, Apr 25, 2021 at 11:38:43AM -0300, Arnaldo Carvalho de Melo wrote:
>> Em Wed, Apr 21, 2021 at 12:18:23PM +0200, Jiri Olsa escreveu:
>>> On Tue, Apr 20, 2021 at 09:21:32PM +0000, Song Liu wrote:
>>>> 
>>>> 
>>>>> On Apr 20, 2021, at 10:31 AM, Jiri Olsa <jolsa@...hat.com> wrote:
>>>>> 
>>>>> On Mon, Apr 19, 2021 at 01:36:48PM -0700, Song Liu wrote:
>>>>> 
>>>>> SNIP
>>>>> 
>>>>>> 	if (stat_config.initial_delay < 0) {
>>>>>> @@ -784,11 +790,11 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
>>>>>> 	if (affinity__setup(&affinity) < 0)
>>>>>> 		return -1;
>>>>>> 
>>>>>> -	if (target__has_bpf(&target)) {
>>>>>> -		evlist__for_each_entry(evsel_list, counter) {
>>>>>> -			if (bpf_counter__load(counter, &target))
>>>>>> -				return -1;
>>>>>> -		}
>>>>>> +	evlist__for_each_entry(evsel_list, counter) {
>>>>>> +		if (bpf_counter__load(counter, &target))
>>>>>> +			return -1;
>>>>>> +		if (!evsel__is_bpf(counter))
>>>>>> +			all_counters_use_bpf = false;
>>>>> 
>>>>> could be done in bpf_counter__load, check below:
>>>>> 
>>>>>> 	}
>>>>>> 
>>>>>> 	evlist__for_each_cpu (evsel_list, i, cpu) {
>>>>>> diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c
>>>>>> index 5de991ab46af9..33b1888103dfa 100644
>>>>>> --- a/tools/perf/util/bpf_counter.c
>>>>>> +++ b/tools/perf/util/bpf_counter.c
>>>>>> @@ -790,7 +790,8 @@ int bpf_counter__load(struct evsel *evsel, struct target *target)
>>>>>> {
>>>>>> 	if (target->bpf_str)
>>>>>> 		evsel->bpf_counter_ops = &bpf_program_profiler_ops;
>>>>>> -	else if (target->use_bpf)
>>>>>> +	else if (target->use_bpf ||
>>>>>> +		 evsel__match_bpf_counter_events(evsel->name))
>>>>>> 		evsel->bpf_counter_ops = &bperf_ops;
>>>>> 
>>>>> with:
>>>>> 	else
>>>>> 		all_counters_use_bpf = false;
>>>>> 
>>>>> I was also thinking of oving it to evlist, but it's sat specific,
>>>>> so I think it's good as static.. thanks for changing the implementation
>>>> 
>>>> Hmm... then we need to somehow make all_counters_use_bpf visible in
>>>> bpf_counter.c, which won't be very clean. Also, since this is stat 
>>>> specific, I guess it is better to keep it inside builtin-stat.c?
>>>> The runtime overhead should be minimal. 
>>> 
>>> ah it's different file :) then it's better as it is, sorry
>> 
>> Is this a Reviewed-by?
> 
> there's still the matter of disable callback:
>  https://lore.kernel.org/lkml/YH8Pw4m0w6DuuEXo@krava/
> 
> it looks like now it could wrong value if we don't disable it

Sorry for the delay. I will add the disable part and send v5 soon. 

Song