linux-kernel - Re: [PATCH v5 4/5] perf stat: Save aggr value to first member of prev_raw

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Message-ID: <20200518124826.GF3726797@krava>
Date:   Mon, 18 May 2020 14:48:26 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Jin Yao <yao.jin@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v5 4/5] perf stat: Save aggr value to first member of
 prev_raw_counts

On Thu, May 14, 2020 at 01:36:37PM +0800, Jin Yao wrote:
> To collect the overall statistics for interval mode, we copy the
> counts from evsel->prev_raw_counts to evsel->counts.
> 
> For AGGR_GLOBAL mode, because the perf_stat_process_counter creates
> aggr values from per cpu values, but the per cpu values are 0,
> so the calculated aggr values will be always 0.
> 
> This patch uses a trick that saves the previous aggr value to
> the first member of perf_counts, then aggr calculation in
> process_counter_values can work correctly for AGGR_GLOBAL.
> 
> Signed-off-by: Jin Yao <yao.jin@...ux.intel.com>
> ---
>  tools/perf/util/stat.c | 10 ++++++++++
>  tools/perf/util/stat.h |  1 +
>  2 files changed, 11 insertions(+)
> 
> diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
> index aadc723ce871..fbabdd5b9b62 100644
> --- a/tools/perf/util/stat.c
> +++ b/tools/perf/util/stat.c
> @@ -249,6 +249,16 @@ void perf_evlist__copy_prev_raw_counts(struct evlist *evlist)
>  		perf_evsel__copy_prev_raw_counts(evsel);
>  }
>  

much better, please put some comments in here explaning wha
is this for, because it's not obvious ;-)

thanks,
jirka

> +void perf_evlist__save_aggr_prev_raw_counts(struct evlist *evlist)
> +{
> +	struct evsel *evsel;
> +
> +	evlist__for_each_entry(evlist, evsel) {
> +		*perf_counts(evsel->prev_raw_counts, 0, 0) =
> +			evsel->prev_raw_counts->aggr;
> +	}
> +}
> +
>  static void zero_per_pkg(struct evsel *counter)
>  {
>  	if (counter->per_pkg_mask)
> diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
> index 62cf72c71869..18ead55756cc 100644
> --- a/tools/perf/util/stat.h
> +++ b/tools/perf/util/stat.h
> @@ -199,6 +199,7 @@ void perf_evlist__free_stats(struct evlist *evlist);
>  void perf_evlist__reset_stats(struct evlist *evlist);
>  void perf_evlist__reset_prev_raw_counts(struct evlist *evlist);
>  void perf_evlist__copy_prev_raw_counts(struct evlist *evlist);
> +void perf_evlist__save_aggr_prev_raw_counts(struct evlist *evlist);
>  
>  int perf_stat_process_counter(struct perf_stat_config *config,
>  			      struct evsel *counter);
> -- 
> 2.17.1
>