linux-kernel - [PATCH] perf: Util.py add_stats() computes the mean correctly

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Message-Id: <20170809053149.14092-1-dima@secretsauce.net>
Date:   Tue,  8 Aug 2017 22:31:49 -0700
From:   Dima Kogan <dima@...retsauce.net>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        linux-kernel@...r.kernel.org
Cc:     Dima Kogan <dima@...retsauce.net>
Subject: [PATCH] perf: Util.py add_stats() computes the mean correctly

add_stats() is a utility function for perf scripts to accumulate a value, and
keep track of some statistics. The mean is one of the statistics it keeps track
of, but due to a bug, this wasn't being computed properly. This patch makes the
computation correct

Signed-off-by: Dima Kogan <dima@...retsauce.net>
---
 tools/perf/scripts/python/Perf-Trace-Util/lib/Perf/Trace/Util.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/scripts/python/Perf-Trace-Util/lib/Perf/Trace/Util.py b/tools/perf/scripts/python/Perf-Trace-Util/lib/Perf/Trace/Util.py
index 1d95009592eb..3d1f08b8ba19 100644
--- a/tools/perf/scripts/python/Perf-Trace-Util/lib/Perf/Trace/Util.py
+++ b/tools/perf/scripts/python/Perf-Trace-Util/lib/Perf/Trace/Util.py
@@ -41,7 +41,7 @@ def add_stats(dict, key, value):
 			min = value
 		if value > max:
 			max = value
-		avg = (avg + value) / 2
+		avg = (avg*count + float(value)) / (count + 1)
 		dict[key] = (min, max, avg, count + 1)
 
 def clear_term():
-- 
2.11.0