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runtime: create setGCPercent method for gcControllerState

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This change breaks out the computations done by setGCPercent into
a method on gcControllerState for easier testing later. It leaves behind
the global implementation details.

For #44167.

Change-Id: I3b0cf1475b032fcd4ebbd01cf4e80de0b55ce7b0
Reviewed-on: https://go-review.googlesource.com/c/go/+/306602
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
This commit is contained in:
Michael Anthony Knyszek 2021-04-01 18:09:59 +00:00 committed by Michael Knyszek
parent 9bce7b70fd
commit e7ab1a5ba8
1 changed files with 21 additions and 9 deletions
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30
src/runtime/mgcpacer.go
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@ -255,7 +255,7 @@ func (c *gcControllerState) init(gcPercent int32) {
c.heapMarked = uint64(float64(c.heapMinimum) / (1 + c.triggerRatio))
// This will also compute and set the GC trigger and goal.
_ = setGCPercent(gcPercent)
c.setGCPercent(gcPercent)
}
// startCycle resets the GC controller's state and computes estimates
@ -784,19 +784,31 @@ func gcEffectiveGrowthRatio() float64 {
return egogc
}
// setGCPercent updates gcPercent and all related pacer state.
// Returns the old value of gcPercent.
//
// The world must be stopped, or mheap_.lock must be held.
func (c *gcControllerState) setGCPercent(in int32) int32 {
assertWorldStoppedOrLockHeld(&mheap_.lock)
out := c.gcPercent
if in < 0 {
in = -1
}
c.gcPercent = in
c.heapMinimum = defaultHeapMinimum * uint64(c.gcPercent) / 100
// Update pacing in response to gcPercent change.
c.commit(c.triggerRatio)
return out
}
//go:linkname setGCPercent runtime/debug.setGCPercent
func setGCPercent(in int32) (out int32) {
// Run on the system stack since we grab the heap lock.
systemstack(func() {
lock(&mheap_.lock)
out = gcController.gcPercent
if in < 0 {
in = -1
}
gcController.gcPercent = in
gcController.heapMinimum = defaultHeapMinimum * uint64(gcController.gcPercent) / 100
// Update pacing in response to gcPercent change.
gcController.commit(gcController.triggerRatio)
out = gcController.setGCPercent(in)
unlock(&mheap_.lock)
})