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

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Message-ID: <YIWH6mKgIvPSfXRP@krava>
Date:   Sun, 25 Apr 2021 17:16:58 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Song Liu <songliubraving@...com>, 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 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

jirka