runtime: avoid a bit of unneeded work when MemProfileRate==1
Change-Id: I1dc355bcaeb0e5fb06a7fddc4cf5db596d22e0b3
Reviewed-on: https://go-review.googlesource.com/c/go/+/236148
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Emmanuel Odeke <emmanuel@orijtech.com>
Reviewed-by: Austin Clements <austin@google.com>
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go
index 551acd0..f20ded5 100644
--- a/src/runtime/malloc.go
+++ b/src/runtime/malloc.go
@@ -1221,6 +1221,13 @@
// distribution (exp(MemProfileRate)), so the best return value is a random
// number taken from an exponential distribution whose mean is MemProfileRate.
func nextSample() uintptr {
+ if MemProfileRate == 1 {
+ // Callers assign our return value to
+ // mcache.next_sample, but next_sample is not used
+ // when the rate is 1. So avoid the math below and
+ // just return something.
+ return 0
+ }
if GOOS == "plan9" {
// Plan 9 doesn't support floating point in note handler.
if g := getg(); g == g.m.gsignal {
