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Date:   Thu, 22 Nov 2018 01:58:11 -0200
From:   Arnaldo Carvalho de Melo <acme@redhat.com>
To:     Stephane Eranian <eranian@google.com>
Cc:     linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@elte.hu,
        jolsa@redhat.com, acme@kernel.org
Subject: Re: [PATCH] perf stat: fix csv mode column output for non-cgroup
 events
Message-ID: <20181122035811.GD5468@redhat.com>
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Em Wed, Nov 07, 2018 at 02:50:45AM -0800, Stephane Eranian escreveu:
> When using the -x option, perf stat prints csv-style output
> with one event per line.  For each event, it prints the count,
> the unit, the event name, the cgroup, and a bunch of other event
> specific fields (such as insn per cycles).
> 
> When you use csv-style mode, you expect a normalized output where
> each event is printed with the same number of fields regardless of
> what it is so it can easily be imported into a spreadsheet or parsed.
> For instance, if an event does not have a unit, then print an empty field
> for it. Although this approach was implemented for the unit, it was not
> for the cgroup.  When mixing cgroup and non-cgroup events, then non-cgroup
> events would not show an empty field, instead the next field was printed,
> make columns not line up correctly.
> 
> This patch fixes the cgroup output issues by forcing an empty field
> for non-cgroup events as soon as one event has cgroup.

Looks sane, that nr_cgroups global variable at some point has to go to
the evlist, but that is not introduced by this patch, Jiri, are you ok
with it as well?

- Arnaldo
 
> Before:
> <not counted> @ @cycles @foo    @ 0    @100.00@@
> 2531614       @ @cycles @6420922@100.00@    @
> 
> foo cgroup lines up with time_running!
> 
> After:
> <not counted> @ @cycles @foo @0       @100.00@@
> 2594834       @ @cycles @    @5287372 @100.00@@
> 
> Fields line up.
> 
> Signed-off-by: Stephane Eranian <eranian@google.com>
> ---
>  tools/perf/util/stat-display.c | 16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> index e7b4c44ebb62..665ee374fc01 100644
> --- a/tools/perf/util/stat-display.c
> +++ b/tools/perf/util/stat-display.c
> @@ -59,6 +59,15 @@ static void print_noise(struct perf_stat_config *config,
>  	print_noise_pct(config, stddev_stats(&ps->res_stats[0]), avg);
>  }
>  
> +static void print_cgroup(struct perf_stat_config *config, struct perf_evsel *evsel)
> +{
> +	if (nr_cgroups) {
> +		const char *cgrp_name = evsel->cgrp ? evsel->cgrp->name  : "";
> +		fprintf(config->output, "%s%s", config->csv_sep, cgrp_name);
> +	}
> +}
> +
> +
>  static void aggr_printout(struct perf_stat_config *config,
>  			  struct perf_evsel *evsel, int id, int nr)
>  {
> @@ -336,8 +345,7 @@ static void abs_printout(struct perf_stat_config *config,
>  
>  	fprintf(output, "%-*s", config->csv_output ? 0 : 25, perf_evsel__name(evsel));
>  
> -	if (evsel->cgrp)
> -		fprintf(output, "%s%s", config->csv_sep, evsel->cgrp->name);
> +	print_cgroup(config, evsel);
>  }
>  
>  static bool is_mixed_hw_group(struct perf_evsel *counter)
> @@ -431,9 +439,7 @@ static void printout(struct perf_stat_config *config, int id, int nr,
>  			config->csv_output ? 0 : -25,
>  			perf_evsel__name(counter));
>  
> -		if (counter->cgrp)
> -			fprintf(config->output, "%s%s",
> -				config->csv_sep, counter->cgrp->name);
> +		print_cgroup(config, counter);
>  
>  		if (!config->csv_output)
>  			pm(config, &os, NULL, NULL, "", 0);
> -- 
> 2.7.4