From: Peter Weinberger <pjw@google.com>
Date: Fri, 28 Oct 2016 19:12:18 +0000 (-0400)
Subject: runtime: ensure elapsed cycles are not negative
X-Git-Tag: go1.8beta1~474
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=a1b6e1692b063488cfcc51c258b159ccce4f7d23;p=gostls13.git

runtime: ensure elapsed cycles are not negative

On solaris/amd64 sometimes the reported cycle count is negative. Replace
with 0.

Change-Id: I364eea5ca072281245c7ab3afb0bf69adc3a8eae
Reviewed-on: https://go-review.googlesource.com/32258
Reviewed-by: Ian Lance Taylor <iant@golang.org>
---

diff --git a/src/runtime/mprof.go b/src/runtime/mprof.go
index b3452f2c87..fc06d8dbe7 100644
--- a/src/runtime/mprof.go
+++ b/src/runtime/mprof.go
@@ -346,6 +346,9 @@ func SetMutexProfileFraction(rate int) int {
 
 //go:linkname mutexevent sync.event
 func mutexevent(cycles int64, skip int) {
+	if cycles < 0 {
+		cycles = 0
+	}
 	rate := int64(atomic.Load64(&mutexprofilerate))
 	// TODO(pjw): measure impact of always calling fastrand vs using something
 	// like malloc.go:nextSample()