[PATCH] perf stat: display cvs output for --null runs

[Jiri Olsa]

Adding support to display CVS values for --null runs as requested
by Ingo. It's only for --null run so it does not mess up with
standard CVS output.

For single --null run in CSV mode perf displays elapsed time:

  $ perf stat --null -x ';' true
  0.000496

For multiple --null run in CSV mode perf displays fields in this order:

  - average elapsed time
  - standard deviation

  $ perf stat -r 5  --null -x ';' true
  0.000339;0.000026

If --table is specified for above case, perf also displays new line
for every individual run with fields:

  - elapsed time
  - delta from average ellapsed time

  $ perf stat -r 5 --table  --null -x ';' true
  0.000496;0.000106
  0.000363;-0.000027
  0.000355;-0.000035
  0.000372;-0.000018
  0.000361;-0.000029
  0.000390;0.000027

The last line shows average elapsed time with standard deviation.

Requested-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-l44kt096zzsjwi3l9hjw1lle@xxxxxxxxxxxxxx
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
 tools/perf/Documentation/perf-stat.txt | 30 ++++++++++++++++
 tools/perf/util/stat-display.c         | 48 +++++++++++++++++++-------
 2 files changed, 65 insertions(+), 13 deletions(-)

diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 39c05f89104e..c07f018f3b4b 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -368,6 +368,36 @@ The fields are in this order:
 
 Additional metrics may be printed with all earlier fields being empty.
 
+For single --null run in CSV mode perf displays elapsed time:
+
+  $ perf stat --null -x ';' true
+  0.000496
+
+For multiple --null run in CSV mode perf displays fields in this order:
+
+  - average elapsed time
+  - standard deviation
+
+  $ perf stat -r 5  --null -x ';' true
+  0.000339;0.000026
+
+If --table is specified for above case, perf also displays new line
+for every individual run with fields:
+
+  - elapsed time
+  - delta from average ellapsed time
+
+  $ perf stat -r 5 --table  --null -x ';' true
+  0.000496;0.000106
+  0.000363;-0.000027
+  0.000355;-0.000035
+  0.000372;-0.000018
+  0.000361;-0.000029
+  0.000390;0.000027
+
+The last line shows average elapsed time with standard deviation.
+
+
 SEE ALSO
 --------
 linkperf:perf-top[1], linkperf:perf-list[1]
diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index 3324f23c7efc..8cb4e37a0417 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -1013,22 +1013,29 @@ static void print_table(struct perf_stat_config *config,
 	while (tmp[indent] == ' ')
 		indent++;
 
-	fprintf(output, "%*s# Table of individual measurements:\n", indent, "");
+	if (!config->csv_output)
+		fprintf(output, "%*s# Table of individual measurements:\n", indent, "");
 
 	for (idx = 0; idx < config->run_count; idx++) {
 		double run = (double) config->walltime_run[idx] / NSEC_PER_SEC;
 		int h, n = 1 + abs((int) (100.0 * (run - avg)/run) / 5);
 
-		fprintf(output, " %17.*f (%+.*f) ",
-			precision, run, precision, run - avg);
+		if (!config->csv_output) {
+			fprintf(output, " %17.*f (%+.*f) ",
+				precision, run, precision, run - avg);
 
-		for (h = 0; h < n; h++)
-			fprintf(output, "#");
+			for (h = 0; h < n; h++)
+				fprintf(output, "#");
+
+		} else {
+			fprintf(output, "%f%s%f", run, config->csv_sep, run - avg);
+		}
 
 		fprintf(output, "\n");
 	}
 
-	fprintf(output, "\n%*s# Final result:\n", indent, "");
+	if (!config->csv_output)
+		fprintf(output, "\n%*s# Final result:\n", indent, "");
 }
 
 static double timeval2double(struct timeval *t)
@@ -1042,13 +1049,23 @@ static void print_footer(struct perf_stat_config *config)
 	FILE *output = config->output;
 	int n;
 
-	if (!config->null_run)
+	/*
+	 * Display csv output for null run, but do
+	 * not mess up with standard csv mode.
+	 */
+	if (config->csv_output && !config->null_run)
+		return;
+
+	if (!config->csv_output && !config->null_run)
 		fprintf(output, "\n");
 
 	if (config->run_count == 1) {
-		fprintf(output, " %17.9f seconds time elapsed", avg);
+		if (!config->csv_output)
+			fprintf(output, " %17.9f seconds time elapsed", avg);
+		else
+			fprintf(output, "%f", avg);
 
-		if (config->ru_display) {
+		if (!config->csv_output && config->ru_display) {
 			double ru_utime = timeval2double(&config->ru_data.ru_utime);
 			double ru_stime = timeval2double(&config->ru_data.ru_stime);
 
@@ -1067,11 +1084,16 @@ static void print_footer(struct perf_stat_config *config)
 		if (config->walltime_run_table)
 			print_table(config, output, precision, avg);
 
-		fprintf(output, " %17.*f +- %.*f seconds time elapsed",
-			precision, avg, precision, sd);
+		if (!config->csv_output) {
+			fprintf(output, " %17.*f +- %.*f seconds time elapsed",
+				precision, avg, precision, sd);
 
-		print_noise_pct(config, sd, avg);
+			print_noise_pct(config, sd, avg);
+		} else {
+			fprintf(output, "%f%s%f", avg, config->csv_sep, sd);
+		}
 	}
+
 	fprintf(output, "\n\n");
 
 	if (config->print_free_counters_hint &&
@@ -1148,7 +1170,7 @@ perf_evlist__print_counters(struct perf_evlist *evlist,
 		break;
 	}
 
-	if (!interval && !config->csv_output)
+	if (!interval)
 		print_footer(config);
 
 	fflush(config->output);
-- 
2.20.1