linux-kernel - Re: [PATCH v1 03/22] perf metrics: Don't scale counts going into metrics

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Message-ID: <e685d636-52cd-b34a-2d10-90c16b2e57cf@linux.intel.com>
Date:   Thu, 29 Sep 2022 16:48:21 +0800
From:   Xing Zhengjun <zhengjun.xing@...ux.intel.com>
To:     Ian Rogers <irogers@...gle.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>, perry.taylor@...el.com,
        caleb.biggers@...el.com, kshipra.bopardikar@...el.com,
        samantha.alt@...el.com, ahmad.yasin@...el.com,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        John Garry <john.garry@...wei.com>,
        James Clark <james.clark@....com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Miaoqian Lin <linmq006@...il.com>,
        Florian Fischer <florian.fischer@...q.space>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v1 03/22] perf metrics: Don't scale counts going into
 metrics



On 9/28/2022 3:21 PM, Ian Rogers wrote:
> Counts are scaled prior to going into saved_value, reverse the scaling
> so that metrics don't double scale values.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>   tools/perf/util/stat-shadow.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
> index 9e1eddeff21b..b5cedd37588f 100644
> --- a/tools/perf/util/stat-shadow.c
> +++ b/tools/perf/util/stat-shadow.c
> @@ -865,11 +865,16 @@ static int prepare_metric(struct evsel **metric_events,
>   			if (!v)
>   				break;
>   			stats = &v->stats;
> -			scale = 1.0;
> +			/*
> +			 * If an event was scaled during stat gathering, reverse
> +			 * the scale before computing the metric.
> +			 */
> +			scale = 1.0 / metric_events[i]->scale;
> +
This look likes not work for kernel side events like 
/sys/devices/uncore_imc_*/events/cas_count_read(write).

>   			source_count = evsel__source_count(metric_events[i]);
>   
>   			if (v->metric_other)
> -				metric_total = v->metric_total;
> +				metric_total = v->metric_total * scale;
>   		}
>   		n = strdup(evsel__metric_id(metric_events[i]));
>   		if (!n)

-- 
Zhengjun Xing