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authorDavid Ahern <dsahern@gmail.com>2013-05-25 18:24:48 -0600
committerArnaldo Carvalho de Melo <acme@redhat.com>2013-05-28 16:24:04 +0300
commit45528f7c699a71d2f3096173980aadd43dff6eaa (patch)
tree88090f64f8729195ad68386d3693be18a8102dd3 /tools
parent6ca5f3081f903e2b25e58a061ddad486f846561e (diff)
downloadlinux-45528f7c699a71d2f3096173980aadd43dff6eaa.tar.bz2
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 23742126f47c..7c59c28afcc5 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);