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perf stat: Fix -nan% output in perf stat noise printouts

tip:perf/stat tip-bot for Ingo Molnar 1 participant 1 message Apr 27, 2011 perf events

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Commit-ID:  f99844cb76b7d347711c22cdcb94266b7214141f
Gitweb:     http://git.kernel.org/tip/f99844cb76b7d347711c22cdcb94266b7214141f
Author:     Ingo Molnar <[email protected]>
AuthorDate: Wed, 27 Apr 2011 05:35:39 +0200
Committer:  Ingo Molnar <[email protected]>
CommitDate: Tue, 26 Apr 2011 20:04:57 +0200

perf stat: Fix -nan% output in perf stat noise printouts

Before:

0 CPU-migrations # 0.000 M/sec ( +- -nan% )

After:

0 CPU-migrations # 0.000 M/sec ( +- 0.00% )

Also factor out the noise printing function.

Acked-by Peter Zijlstra <[email protected]>
Acked-by Arnaldo Carvalho de Melo <[email protected]>
Cc Frederic Weisbecker <[email protected]>
Link http://lkml.kernel.org/n/[email protected] open here
Signed-off-by Ingo Molnar <[email protected]>
---
 tools/perf/builtin-stat.c |   18 +++++++++++++-----
 1 files changed, 13 insertions(+), 5 deletions(-)
tools/perf/builtin-stat.c +13 -5
index 924d18c..845ded8 100644
@@ -382,6 +382,16 @@ static int run_perf_stat(int argc __used, const char **argv)
 	return WEXITSTATUS(status);
 }
 
+static void print_noise_pct(double total, double avg)
+{
+	double pct = 0.0;
+
+	if (avg)
+		pct = 100.0*total/avg;
+
+	fprintf(stderr, "  ( +-%6.2f%% )", pct);
+}
+
 static void print_noise(struct perf_evsel *evsel, double avg)
 {
 	struct perf_stat *ps;

@@ -390,8 +400,7 @@ static void print_noise(struct perf_evsel *evsel, double avg)
 		return;
 
 	ps = evsel->priv;
-	fprintf(stderr, "   ( +- %7.3f%% )",
-			100 * stddev_stats(&ps->res_stats[0]) / avg);
+	print_noise_pct(stddev_stats(&ps->res_stats[0]), avg);
 }
 
 static void nsec_printout(int cpu, struct perf_evsel *evsel, double avg)

@@ -635,9 +644,8 @@ static void print_stat(int argc, const char **argv)
 		fprintf(stderr, " %18.9f  seconds time elapsed",
 				avg_stats(&walltime_nsecs_stats)/1e9);
 		if (run_count > 1) {
-			fprintf(stderr, "   ( +-%5.2f%% )",
-				100*stddev_stats(&walltime_nsecs_stats) /
-				avg_stats(&walltime_nsecs_stats));
+			print_noise_pct(stddev_stats(&walltime_nsecs_stats),
+					avg_stats(&walltime_nsecs_stats));
 		}
 		fprintf(stderr, "\n\n");
 	}