linux-kernel - Re: [PATCH v1 17/40] perf evsel: Modify group pmu name for software events

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Date:   Thu, 27 Apr 2023 16:12:40 -0400
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Ian Rogers <irogers@...gle.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ahmad Yasin <ahmad.yasin@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Stephane Eranian <eranian@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Perry Taylor <perry.taylor@...el.com>,
        Samantha Alt <samantha.alt@...el.com>,
        Caleb Biggers <caleb.biggers@...el.com>,
        Weilin Wang <weilin.wang@...el.com>,
        Edward Baker <edward.baker@...el.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Florian Fischer <florian.fischer@...q.space>,
        Rob Herring <robh@...nel.org>,
        Zhengjun Xing <zhengjun.xing@...ux.intel.com>,
        John Garry <john.g.garry@...cle.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Sumanth Korikkar <sumanthk@...ux.ibm.com>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Leo Yan <leo.yan@...aro.org>,
        Yang Jihong <yangjihong1@...wei.com>,
        James Clark <james.clark@....com>,
        Suzuki Poulouse <suzuki.poulose@....com>,
        Kang Minchul <tegongkang@...il.com>,
        Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 17/40] perf evsel: Modify group pmu name for software
 events



On 2023-04-26 3:00 a.m., Ian Rogers wrote:
> If we have a group of {cycles,faults} then we need the faults software
> event to appear to be on the same PMU as cycles so that we don't split
> the group in parse_events__sort_events_and_fix_groups. This case is
> relatively easy as cycles is the leader and will have a PMU name. In
> the reverse case, {faults,cycles} we still need faults to appear to
> have the PMU name of cycles but the old behavior is just to return
> "cpu". For hybrid this fails as cycles will be on "cpu_core" or
> "cpu_atom", causing faults to be split into a different group.
> 
> Change the behavior for software events so that the whole group is
> searched for the named PMU.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>

Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>

Thanks,
Kan

> ---
>  tools/perf/util/evsel.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 1cd04b5998d2..63522322e118 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -829,23 +829,26 @@ bool evsel__name_is(struct evsel *evsel, const char *name)
>  
>  const char *evsel__group_pmu_name(const struct evsel *evsel)
>  {
> -	const struct evsel *leader;
> +	struct evsel *leader, *pos;
>  
>  	/* If the pmu_name is set use it. pmu_name isn't set for CPU and software events. */
>  	if (evsel->pmu_name)
>  		return evsel->pmu_name;
>  	/*
>  	 * Software events may be in a group with other uncore PMU events. Use
> -	 * the pmu_name of the group leader to avoid breaking the software event
> -	 * out of the group.
> +	 * the pmu_name of the first non-software event to avoid breaking the
> +	 * software event out of the group.
>  	 *
>  	 * Aux event leaders, like intel_pt, expect a group with events from
>  	 * other PMUs, so substitute the AUX event's PMU in this case.
>  	 */
>  	leader  = evsel__leader(evsel);
> -	if ((evsel->core.attr.type == PERF_TYPE_SOFTWARE || evsel__is_aux_event(leader)) &&
> -	    leader->pmu_name) {
> -		return leader->pmu_name;
> +	if (evsel->core.attr.type == PERF_TYPE_SOFTWARE || evsel__is_aux_event(leader)) {
> +		/* Starting with the leader, find the first event with a named PMU. */
> +		for_each_group_evsel(pos, leader) {
> +			if (pos->pmu_name)
> +				return pos->pmu_name;
> +		}
>  	}
>  
>  	return "cpu";