linux-kernel - Re: [PATCH v2] perf pmu: Fix alias events list

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Date:   Wed, 22 Dec 2021 14:56:34 +0800
From:   Xing Zhengjun <zhengjun.xing@...ux.intel.com>
To:     John Garry <john.garry@...wei.com>, peterz@...radead.org,
        mingo@...hat.com, acme@...nel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...hat.com,
        namhyung@...nel.org, irogers@...gle.com, kan.liang@...ux.intel.com
Cc:     linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] perf pmu: Fix alias events list



On 12/22/2021 12:11 AM, John Garry wrote:
> Commit 0e0ae8742207 ("perf list: Display hybrid PMU events with cpu type")
> changes the event list for uncore PMUs or arm64 heterogeneous CPU systems,
> such that duplicate aliases are incorrectly listed per PMU (which they
> should not be), like:
> 
> ./perf list
> ...
> unc_cbo_cache_lookup.any_es
> [Unit: uncore_cbox L3 Lookup any request that access cache and found
> line in E or S-state]
> unc_cbo_cache_lookup.any_es
> [Unit: uncore_cbox L3 Lookup any request that access cache and found
> line in E or S-state]
> unc_cbo_cache_lookup.any_i
> [Unit: uncore_cbox L3 Lookup any request that access cache and found
> line in I-state]
> unc_cbo_cache_lookup.any_i
> [Unit: uncore_cbox L3 Lookup any request that access cache and found
> line in I-state]
> ...
> 
> Notice how the events are listed twice.
> 
> The named commit changed how we remove duplicate events, in that events
> for different PMUs are not treated as duplicates. I suppose this is to
> handle how "Each hybrid pmu event has been assigned with a pmu name".
> 
> Fix PMU alias listing by restoring behaviour to remove duplicates for
> non-hybrid PMUs.
> 
> Fixes: 0e0ae8742207 ("perf list: Display hybrid PMU events with cpu type")
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
> 
> Difference in v2:
> - Change duplicate check to explicitly check for hybrid PMU
> 
> @Zhengjun Xing, Can you please check this new version? Thanks!

Tested this new version patch on both hybrid and non-hybrid PMU x86 
systems, it works OK with no duplicate events for the uncore.

Tested-by: Zhengjun Xing <zhengjun.xing@...ux.intel.com>

> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 6ae58406f4fc..8dfbba15aeb8 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -1659,6 +1659,21 @@ bool is_pmu_core(const char *name)
>   	return !strcmp(name, "cpu") || is_arm_pmu_core(name);
>   }
>   
> +static bool pmu_alias_is_duplicate(struct sevent *alias_a,
> +				   struct sevent *alias_b)
> +{
> +	/* Different names -> never duplicates */
> +	if (strcmp(alias_a->name, alias_b->name))
> +		return false;
> +
> +	/* Don't remove duplicates for hybrid PMUs */
> +	if (perf_pmu__is_hybrid(alias_a->pmu) &&
> +	    perf_pmu__is_hybrid(alias_b->pmu))
> +		return false;
> +
> +	return true;
> +}
> +
>   void print_pmu_events(const char *event_glob, bool name_only, bool quiet_flag,
>   			bool long_desc, bool details_flag, bool deprecated,
>   			const char *pmu_name)
> @@ -1744,12 +1759,8 @@ void print_pmu_events(const char *event_glob, bool name_only, bool quiet_flag,
>   	qsort(aliases, len, sizeof(struct sevent), cmp_sevent);
>   	for (j = 0; j < len; j++) {
>   		/* Skip duplicates */
> -		if (j > 0 && !strcmp(aliases[j].name, aliases[j - 1].name)) {
> -			if (!aliases[j].pmu || !aliases[j - 1].pmu ||
> -			    !strcmp(aliases[j].pmu, aliases[j - 1].pmu)) {
> -				continue;
> -			}
> -		}
> +		if (j > 0 && pmu_alias_is_duplicate(&aliases[j], &aliases[j - 1]))
> +			continue;
>   
>   		if (name_only) {
>   			printf("%s ", aliases[j].name);

-- 
Zhengjun Xing