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From:   Stephane Eranian <eranian@google.com>
To:     linux-kernel@vger.kernel.org
Cc:     acme@redhat.com, peterz@infradead.org, mingo@elte.hu,
        jolsa@redhat.com
Subject: [PATCH] perf stat: fix csv mode column output for non-cgroup events
Date:   Wed,  7 Nov 2018 02:50:45 -0800
Message-Id: <1541587845-9150-1-git-send-email-eranian@google.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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.

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