Messages in this thread Patch in this message | | | Date | Fri, 31 May 2013 04:51:11 -0700 | From | tip-bot for David Ahern <> | Subject | [tip:perf/core] perf stats: Fix divide by 0 in variance |
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Commit-ID: 45528f7c699a71d2f3096173980aadd43dff6eaa Gitweb: http://git.kernel.org/tip/45528f7c699a71d2f3096173980aadd43dff6eaa Author: David Ahern <dsahern@gmail.com> AuthorDate: Sat, 25 May 2013 18:24:48 -0600 Committer: Arnaldo Carvalho de Melo <acme@redhat.com> CommitDate: Tue, 28 May 2013 16:24:04 +0300
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> --- tools/perf/util/stat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c index 2374212..7c59c28 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);
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