From: Keith Randall <khr@golang.org>
Date: Fri, 9 May 2014 22:50:57 +0000 (-0700)
Subject: runtime: be a lot more lenient on smhasher avalanche test.
X-Git-Tag: go1.3beta2~108
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=711d1ad7eebc4aecfb3a326f16af206b7b99ff6c;p=gostls13.git

runtime: be a lot more lenient on smhasher avalanche test.

Fixes #7943

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/98170043
---

diff --git a/src/pkg/runtime/hash_test.go b/src/pkg/runtime/hash_test.go
index 312c4be8e9..1c11e0538d 100644
--- a/src/pkg/runtime/hash_test.go
+++ b/src/pkg/runtime/hash_test.go
@@ -397,10 +397,10 @@ func avalancheTest1(t *testing.T, k Key) {
 	// all sums inside those bounds with 99% probability.
 	N := n * hashSize
 	var c float64
-	// find c such that Prob(mean-c*stddev < x < mean+c*stddev)^N > .99
-	for c = 0.0; math.Pow(math.Erf(c/math.Sqrt(2)), float64(N)) < .99; c += .1 {
+	// find c such that Prob(mean-c*stddev < x < mean+c*stddev)^N > .9999
+	for c = 0.0; math.Pow(math.Erf(c/math.Sqrt(2)), float64(N)) < .9999; c += .1 {
 	}
-	c *= 2.0 // allowed slack - we don't need to be perfectly random
+	c *= 4.0 // allowed slack - we don't need to be perfectly random
 	mean := .5 * REP
 	stddev := .5 * math.Sqrt(REP)
 	low := int(mean - c*stddev)