linux-kernel - Re: [PATCH] perf stat: Merge uncore events by default for hybrid platform

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Date:   Tue, 6 Jul 2021 21:51:07 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     "Jin, Yao" <yao.jin@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH] perf stat: Merge uncore events by default for hybrid
 platform

On Tue, Jul 06, 2021 at 10:32:57AM +0800, Jin, Yao wrote:
> Hi,
> 
> On 6/16/2021 2:30 PM, Jin Yao wrote:
> > On hybrid platform, by default stat aggregates and reports the event counts
> > per pmu. For example,
> > 
> >    # perf stat -e cycles -a true
> > 
> >     Performance counter stats for 'system wide':
> > 
> >             1,400,445      cpu_core/cycles/
> >               680,881      cpu_atom/cycles/
> > 
> >           0.001770773 seconds time elapsed
> > 
> > While for uncore events, that's not a suitable method. Uncore has nothing
> > to do with hybrid. So for uncore events, we aggregate event counts from all
> > PMUs and report the counts without PMUs.
> > 
> > Before:
> > 
> >    # perf stat -e arb/event=0x81,umask=0x1/,arb/event=0x84,umask=0x1/ -a true
> > 
> >     Performance counter stats for 'system wide':
> > 
> >                 2,058      uncore_arb_0/event=0x81,umask=0x1/
> >                 2,028      uncore_arb_1/event=0x81,umask=0x1/
> >                     0      uncore_arb_0/event=0x84,umask=0x1/
> >                     0      uncore_arb_1/event=0x84,umask=0x1/
> > 
> >           0.000614498 seconds time elapsed
> > 
> > After:
> > 
> >    # perf stat -e arb/event=0x81,umask=0x1/,arb/event=0x84,umask=0x1/ -a true
> > 
> >     Performance counter stats for 'system wide':
> > 
> >                 3,996      arb/event=0x81,umask=0x1/
> >                     0      arb/event=0x84,umask=0x1/
> > 
> >           0.000630046 seconds time elapsed
> > 
> > Of course, we also keep the '--no-merge' still works for uncore events.
> > 
> >    # perf stat -e arb/event=0x81,umask=0x1/,arb/event=0x84,umask=0x1/ --no-merge true
> > 
> >     Performance counter stats for 'system wide':
> > 
> >                 1,952      uncore_arb_0/event=0x81,umask=0x1/
> >                 1,921      uncore_arb_1/event=0x81,umask=0x1/
> >                     0      uncore_arb_0/event=0x84,umask=0x1/
> >                     0      uncore_arb_1/event=0x84,umask=0x1/
> > 
> >           0.000575536 seconds time elapsed
> > 
> > Signed-off-by: Jin Yao <yao.jin@...ux.intel.com>
> > ---
> >   tools/perf/builtin-stat.c      |  3 ---
> >   tools/perf/util/stat-display.c | 29 +++++++++++++++++++++++++----
> >   2 files changed, 25 insertions(+), 7 deletions(-)
> > 
> > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> > index f9f74a514315..b67a44982b61 100644
> > --- a/tools/perf/builtin-stat.c
> > +++ b/tools/perf/builtin-stat.c
> > @@ -2442,9 +2442,6 @@ int cmd_stat(int argc, const char **argv)
> >   	evlist__check_cpu_maps(evsel_list);
> > -	if (perf_pmu__has_hybrid())
> > -		stat_config.no_merge = true;
> > -
> >   	/*
> >   	 * Initialize thread_map with comm names,
> >   	 * so we could print it out on output.
> > diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> > index b759dfd633b4..c6070f4684ca 100644
> > --- a/tools/perf/util/stat-display.c
> > +++ b/tools/perf/util/stat-display.c
> > @@ -595,6 +595,19 @@ static void collect_all_aliases(struct perf_stat_config *config, struct evsel *c
> >   	}
> >   }
> > +static bool is_uncore(struct evsel *evsel)
> > +{
> > +	struct perf_pmu *pmu;
> > +
> > +	if (evsel->pmu_name) {
> > +		pmu = perf_pmu__find(evsel->pmu_name);

evsel__find_pmu might be one line shorter? ;-)


> > +		if (pmu)
> > +			return pmu->is_uncore;
> > +	}
> > +
> > +	return false;
> > +}
> > +
> >   static bool collect_data(struct perf_stat_config *config, struct evsel *counter,
> >   			    void (*cb)(struct perf_stat_config *config, struct evsel *counter, void *data,
> >   				       bool first),
> > @@ -603,10 +616,18 @@ static bool collect_data(struct perf_stat_config *config, struct evsel *counter,
> >   	if (counter->merged_stat)
> >   		return false;
> >   	cb(config, counter, data, true);
> > -	if (config->no_merge)
> > -		uniquify_event_name(counter);
> > -	else if (counter->auto_merge_stats)
> > -		collect_all_aliases(config, counter, cb, data);
> > +	if (perf_pmu__has_hybrid()) {
> > +		if (config->no_merge || !is_uncore(counter))

hum, this is all the same except for the !is_uncore condition, right?

could we just add 'config->no_merge || hybrid_uniquify(count)'

that would cover both perf_pmu__has_hybrid and !is_uncore conditions?

jirka

> > +			uniquify_event_name(counter);
> > +		else if (counter->auto_merge_stats)
> > +			collect_all_aliases(config, counter, cb, data);
> > +	} else {
> > +		if (config->no_merge)
> > +			uniquify_event_name(counter);
> > +		else if (counter->auto_merge_stats)
> > +			collect_all_aliases(config, counter, cb, data);
> > +	}
> > +
> >   	return true;
> >   }
> > 
> 
> Any comments for this patch? :)
> 
> Thanks
> Jin Yao
>