linux-kernel - [PATCH 2/9] perf top: Fix percent output when no samples collected

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Date:	Tue, 14 May 2013 11:09:00 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Jiri Olsa <jolsa@...hat.com>, David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>
Subject: [PATCH 2/9] perf top: Fix percent output when no samples collected

From: Namhyung Kim <namhyung.kim@....com>

If there's no sample, kernel and exact percent output at the header
looked like "-nan%".

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/top.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/top.c b/tools/perf/util/top.c
index 54d37a4753c5..f857b51b6bde 100644
--- a/tools/perf/util/top.c
+++ b/tools/perf/util/top.c
@@ -23,20 +23,31 @@
 
 size_t perf_top__header_snprintf(struct perf_top *top, char *bf, size_t size)
 {
-	float samples_per_sec = top->samples / top->delay_secs;
-	float ksamples_per_sec = top->kernel_samples / top->delay_secs;
-	float esamples_percent = (100.0 * top->exact_samples) / top->samples;
+	float samples_per_sec;
+	float ksamples_per_sec;
+	float esamples_percent;
 	struct perf_record_opts *opts = &top->record_opts;
 	struct perf_target *target = &opts->target;
 	size_t ret = 0;
 
+	if (top->samples) {
+		samples_per_sec = top->samples / top->delay_secs;
+		ksamples_per_sec = top->kernel_samples / top->delay_secs;
+		esamples_percent = (100.0 * top->exact_samples) / top->samples;
+	} else {
+		samples_per_sec = ksamples_per_sec = esamples_percent = 0.0;
+	}
+
 	if (!perf_guest) {
+		float ksamples_percent = 0.0;
+
+		if (samples_per_sec)
+			ksamples_percent = (100.0 * ksamples_per_sec) /
+							samples_per_sec;
 		ret = SNPRINTF(bf, size,
 			       "   PerfTop:%8.0f irqs/sec  kernel:%4.1f%%"
 			       "  exact: %4.1f%% [", samples_per_sec,
-			       100.0 - (100.0 * ((samples_per_sec - ksamples_per_sec) /
-					samples_per_sec)),
-				esamples_percent);
+			       ksamples_percent, esamples_percent);
 	} else {
 		float us_samples_per_sec = top->us_samples / top->delay_secs;
 		float guest_kernel_samples_per_sec = top->guest_kernel_samples / top->delay_secs;
-- 
1.7.11.7

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