linux-kernel - Re: [PATCH] perf metrics: Fixes stat cmd cannot parse sys metrics when cpus MIDR mismatch

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Message-ID: <00b3d618-628f-3366-7195-2300468eb450@huawei.com>
Date: Thu, 5 Sep 2024 11:16:18 +0800
From: Yicong Yang <yangyicong@...wei.com>
To: Junhao He <hejunhao3@...wei.com>, <irogers@...gle.com>,
	<peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
	<namhyung@...nel.org>, <mark.rutland@....com>,
	<alexander.shishkin@...ux.intel.com>, <jolsa@...nel.org>,
	<adrian.hunter@...el.com>, <kan.liang@...ux.intel.com>
CC: <yangyicong@...ilicon.com>, <linux-perf-users@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <jonathan.cameron@...wei.com>,
	<linuxarm@...wei.com>, <prime.zeng@...ilicon.com>
Subject: Re: [PATCH] perf metrics: Fixes stat cmd cannot parse sys metrics
 when cpus MIDR mismatch

On 2024/8/7 12:00, Junhao He wrote:
> On some platforms that do not use cpu MIDR mapping, such as hisilicon
> HIP09 platform. The list cmd can display the CPA metrics, but the stat
> cmd cannot work well to parse of CPA metrics.
> 
>   $ perf list metric
>   Metrics:
>     cpa_p0_avg_bw
>          [Average bandwidth of CPA Port 0]
>     cpa_p1_avg_bw
>          [Average bandwidth of CPA Port 1]
>   $ perf stat -M cpa_p0_avg_bw --timeout 1000 --> No error messages output
>   $ echo $?
>   234
> 
> Currently, the metricgroup__parse_groups() expects to find an cpu metric
> table, but the hisilicon/hip09 doesn't uses cpus MIDR to map json events
> and metrics, so pmu_metrics_table__find() will return NULL, than the cmd
> run failed.
> But in metricgroup__add_metric(), the function parse for each sys metric
> and add it to metric_list, which also will get an valid sys metric table.
> So, we can ignore the NULL result of pmu_metrics_table__find() and to use
> the sys metric table.
> 
> metricgroup__parse_groups
>  -> parse_groups
>      -> metricgroup__add_metric_list
>          -> metricgroup__add_metric
>              -> pmu_for_each_sys_metric   --> We've got the sys metric
> 
> Testing:
>   [root@...alhost ~]# perf stat -M cpa_p0_avg_bw --no-merge --timeout 1000
> 
>    Performance counter stats for 'system wide':
> 
>    CPU0        1,001,121,239      cpa_cycles [hisi_sicl0_cpa0]     #     0.00 cpa_p0_avg_bw
>    CPU0                    0      cpa_p0_wr_dat [hisi_sicl0_cpa0]
>    CPU0                    0      cpa_p0_rd_dat_64b [hisi_sicl0_cpa0]
>    CPU0                    0      cpa_p0_rd_dat_32b [hisi_sicl0_cpa0]
>    CPU0        1,001,094,851      cpa_cycles [hisi_sicl2_cpa0]     #     0.00 cpa_p0_avg_bw
>    CPU0                    0      cpa_p0_wr_dat [hisi_sicl2_cpa0]
>    CPU0                    0      cpa_p0_rd_dat_64b [hisi_sicl2_cpa0]
>    CPU0                    0      cpa_p0_rd_dat_32b [hisi_sicl2_cpa0]
> 
>        1.001306160 seconds time elapsed
> 
> Signed-off-by: Junhao He <hejunhao3@...wei.com>

Tested-by: Yicong Yang <yangyicong@...ilicon.com>

The changes looks fine to me, I'd prefer to add some documents for this. See below.

> ---
>  tools/perf/util/metricgroup.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> index 69f6a46402c3..fa62fb3418b6 100644
> --- a/tools/perf/util/metricgroup.c
> +++ b/tools/perf/util/metricgroup.c
> @@ -1123,7 +1123,7 @@ static int metricgroup__add_metric_sys_event_iter(const struct pmu_metric *pm,
>  
>  	ret = add_metric(d->metric_list, pm, d->modifier, d->metric_no_group,
>  			 d->metric_no_threshold, d->user_requested_cpu_list,
> -			 d->system_wide, d->root_metric, d->visited, d->table);
> +			 d->system_wide, d->root_metric, d->visited, d->table ?: table);
>  	if (ret)
>  		goto out;
>  
> @@ -1239,7 +1239,7 @@ static int metricgroup__add_metric(const char *pmu, const char *metric_name, con
>  	int ret;
>  	bool has_match = false;
>  
> -	{
> +	if (table) {

may add a comment here. If !table then the metrics may belong to a system PMU.

>  		struct metricgroup__add_metric_data data = {
>  			.list = &list,
>  			.pmu = pmu,
> @@ -1696,8 +1696,6 @@ int metricgroup__parse_groups(struct evlist *perf_evlist,
>  {
>  	const struct pmu_metrics_table *table = pmu_metrics_table__find();
>  
> -	if (!table)
> -		return -EINVAL;

may add a debug message to mention we're parsing metrics of system PMUs.

Thanks.

>  	if (hardware_aware_grouping)
>  		pr_debug("Use hardware aware grouping instead of traditional metric grouping method\n");
>  
>