From: Andy Pan <panjf2000@gmail.com>
Date: Tue, 5 Sep 2023 09:12:24 +0000 (+0800)
Subject: runtime: fix the miscalculation of memoryLimitGoal in gcPaceScavenger
X-Git-Tag: go1.22rc1~976
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=729f214e3afd61afd924b946745798a8d144aad6;p=gostls13.git

runtime: fix the miscalculation of memoryLimitGoal in gcPaceScavenger

The goal is supposed to be (100-reduceExtraPercent) / 100 * memoryLimit,
as stated in the original design.

Fixes #62449

Change-Id: Ia33acadc3320aa3625814595a24b9631ae8896d9
Reviewed-on: https://go-review.googlesource.com/c/go/+/525555
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Run-TryBot: Andy Pan <panjf2000@gmail.com>
---

diff --git a/src/runtime/mgcscavenge.go b/src/runtime/mgcscavenge.go
index 4c6d6be4f0..b24d830732 100644
--- a/src/runtime/mgcscavenge.go
+++ b/src/runtime/mgcscavenge.go
@@ -172,7 +172,7 @@ func gcPaceScavenger(memoryLimit int64, heapGoal, lastHeapGoal uint64) {
 	// it's simpler.
 
 	// We want to target retaining (100-reduceExtraPercent)% of the heap.
-	memoryLimitGoal := uint64(float64(memoryLimit) * (100.0 - reduceExtraPercent))
+	memoryLimitGoal := uint64(float64(memoryLimit) * (1 - reduceExtraPercent/100.0))
 
 	// mappedReady is comparable to memoryLimit, and represents how much total memory
 	// the Go runtime has committed now (estimated).
@@ -1297,7 +1297,7 @@ const (
 	scavChunkHasFree scavChunkFlags = 1 << iota
 	// scavChunkNoHugePage indicates whether this chunk has had any huge
 	// pages broken by the scavenger.
-	//.
+	//
 	// The negative here is unfortunate, but necessary to make it so that
 	// the zero value of scavChunkData accurately represents the state of
 	// a newly-grown chunk. (New memory is marked as backed by huge pages.)