Re: [PATCH] perf parse-events: Move slots only with topdown

From: "Liang, Kan" <kan.liang@linux.intel.com>
To: Ian Rogers <irogers@google.com>,
	Zhengjun Xing <zhengjun.xing@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Andi Kleen <ak@linux.intel.com>,
	James Clark <james.clark@arm.com>,
	John Garry <john.garry@huawei.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org
Cc: Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH] perf parse-events: Move slots only with topdown
Date: Tue, 22 Mar 2022 07:48:48 -0400	[thread overview]
Message-ID: <ffd440b7-fef9-a5ae-95b7-73c1f8a212ef@linux.intel.com> (raw)
In-Reply-To: <20220321223344.1034479-1-irogers@google.com>

On 3/21/2022 6:33 PM, Ian Rogers wrote:
> If slots isn't with a topdown event then moving it is unnecessary. For
> example {instructions, slots} is re-ordered:
> 
> $ perf stat -e '{instructions,slots}' -a sleep 1
> 
>   Performance counter stats for 'system wide':
> 
>         936,600,825      slots
>         144,440,968      instructions
> 
>         1.006061423 seconds time elapsed
> 
> Which can break tools expecting the command line order to match the
> printed order. It is necessary to move the slots event first when it
> appears with topdown events. Add extra checking so that the slots event
> is only moved in the case of there being a topdown event like:
> 
> $ perf stat -e '{instructions,slots,topdown-fe-bound}' -a sleep 1
> 
>   Performance counter stats for 'system wide':
> 
>          2427568570      slots
>           300927614      instructions
>           551021649      topdown-fe-bound
> 
>         1.001771803 seconds time elapsed
> 
> Fixes: 94dbfd6781a0 ("perf parse-events: Architecture specific leader override")
> Reported-by: Kan Liang <kan.liang@linux.intel.com>
> Signed-off-by: Ian Rogers <irogers@google.com>

Thanks Ian. The patch works well.

Tested-by: Kan Liang <kan.liang@linux.intel.com>

Thanks,
Kan
> ---
>   tools/perf/arch/x86/util/evlist.c | 18 ++++++++++++++----
>   1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/arch/x86/util/evlist.c b/tools/perf/arch/x86/util/evlist.c
> index 8d9b55959256..cfc208d71f00 100644
> --- a/tools/perf/arch/x86/util/evlist.c
> +++ b/tools/perf/arch/x86/util/evlist.c
> @@ -20,17 +20,27 @@ int arch_evlist__add_default_attrs(struct evlist *evlist)
>   
>   struct evsel *arch_evlist__leader(struct list_head *list)
>   {
> -	struct evsel *evsel, *first;
> +	struct evsel *evsel, *first, *slots = NULL;
> +	bool has_topdown = false;
>   
>   	first = list_first_entry(list, struct evsel, core.node);
>   
>   	if (!pmu_have_event("cpu", "slots"))
>   		return first;
>   
> +	/* If there is a slots event and a topdown event then the slots event comes first. */
>   	__evlist__for_each_entry(list, evsel) {
> -		if (evsel->pmu_name && !strcmp(evsel->pmu_name, "cpu") &&
> -			evsel->name && strcasestr(evsel->name, "slots"))
> -			return evsel;
> +		if (evsel->pmu_name && !strcmp(evsel->pmu_name, "cpu") && evsel->name) {
> +			if (strcasestr(evsel->name, "slots")) {
> +				slots = evsel;
> +				if (slots == first)
> +					return first;
> +			}
> +			if (!strncasecmp(evsel->name, "topdown", 7))
> +				has_topdown = true;
> +			if (slots && has_topdown)
> +				return slots;
> +		}
>   	}
>   	return first;
>   }