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authorDavid Ahern <dsahern@gmail.com>2013-05-25 18:24:48 -0600
committerChanho Park <chanho61.park@samsung.com>2014-11-18 11:43:32 +0900
commit7b919888c7b164baeb7f09f609e6abefbf3657d3 (patch)
tree8b211cd66c852f40161728122085f477c7547bdf /tools
parentf48275c5ffba275407db7eb85fad33d510a19726 (diff)
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perf stats: Fix divide by 0 in variance
Number of samples needs to be greater 1 to have a variance. Fixes nan% in perf-kvm-live output. Signed-off-by: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Runzhen Wang <runzhen@linux.vnet.ibm.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1369527896-3650-9-git-send-email-dsahern@gmail.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/util/stat.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index 23742126f47..7c59c28afcc 100644
--- a/tools/perf/util/stat.c
+++ b/tools/perf/util/stat.c
@@ -37,7 +37,7 @@ double stddev_stats(struct stats *stats)
{
double variance, variance_mean;
- if (!stats->n)
+ if (stats->n < 2)
return 0.0;
variance = stats->M2 / (stats->n - 1);