From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758690Ab3EZA2t (ORCPT ); Sat, 25 May 2013 20:28:49 -0400 Received: from mail-pd0-f172.google.com ([209.85.192.172]:41704 "EHLO mail-pd0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758538Ab3EZA0p (ORCPT ); Sat, 25 May 2013 20:26:45 -0400 From: David Ahern To: linux-kernel@vger.kernel.org Cc: acme@ghostprotocols.net, mingo@kernel.org, fweisbec@gmail.com, peterz@infradead.org, jolsa@redhat.com, namhyung@kernel.org, xiaoguangrong@linux.vnet.ibm.com, runzhen@linux.vnet.ibm.com, David Ahern Subject: [PATCH 08/16] perf stats: fix divide by 0 in variance Date: Sat, 25 May 2013 18:24:48 -0600 Message-Id: <1369527896-3650-9-git-send-email-dsahern@gmail.com> X-Mailer: git-send-email 1.7.10.1 In-Reply-To: <1369527896-3650-1-git-send-email-dsahern@gmail.com> References: <1369527896-3650-1-git-send-email-dsahern@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Number of samples needs to be greater 1 to have a variance. Fixes nan% in perf-kvm-live output. Signed-off-by: David Ahern Cc: Arnaldo Carvalho de Melo Cc: Ingo Molnar Cc: Frederic Weisbecker Cc: Peter Zijlstra Cc: Jiri Olsa Cc: Namhyung Kim Cc: Xiao Guangrong Cc: Runzhen Wang --- 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); -- 1.7.10.1