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

[Jin, Yao]

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@xxxxxxxxxxxxxxx>
> ---
>   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);
> +		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))
> +			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