Commit b6e178ed authored by Rick Hudson's avatar Rick Hudson

runtime: set heap minimum default based on GOGC

Currently the heap minimum is set to 4MB which prevents our ability to
collect at every allocation by setting GOGC=0. This adjust the
heap minimum to 4MB*GOGC/100 thus reenabling collecting at every allocation.
Fixes #10681

Change-Id: I912d027dac4b14ae535597e8beefa9ac3fb8ad94
Reviewed-on: https://go-review.googlesource.com/9814Reviewed-by: default avatarAustin Clements <austin@google.com>
Reviewed-by: default avatarRuss Cox <rsc@golang.org>
parent 7bdeab1b
......@@ -130,6 +130,9 @@ const (
// heapminimum is the minimum number of bytes in the heap.
// This cleans up the corner case of where we have a very small live set but a lot
// of allocations and collecting every GOGC * live set is expensive.
// heapminimum is adjust by multiplying it by GOGC/100. In
// the special case of GOGC==0 this will set heapminimum to 0 resulting
// collecting at every allocation even when the heap size is small.
var heapminimum = uint64(4 << 20)
// Initialized from $GOGC. GOGC=off means no GC.
......@@ -141,7 +144,7 @@ func gcinit() {
}
work.markfor = parforalloc(_MaxGcproc)
gcpercent = readgogc()
_ = setGCPercent(readgogc())
for datap := &firstmoduledata; datap != nil; datap = datap.next {
datap.gcdatamask = unrollglobgcprog((*byte)(unsafe.Pointer(datap.gcdata)), datap.edata-datap.data)
datap.gcbssmask = unrollglobgcprog((*byte)(unsafe.Pointer(datap.gcbss)), datap.ebss-datap.bss)
......@@ -149,6 +152,17 @@ func gcinit() {
memstats.next_gc = heapminimum
}
func readgogc() int32 {
p := gogetenv("GOGC")
if p == "" {
return 100
}
if p == "off" {
return -1
}
return int32(atoi(p))
}
// gcenable is called after the bulk of the runtime initialization,
// just before we're about to start letting user code run.
// It kicks off the background sweeper goroutine and enables GC.
......@@ -166,6 +180,7 @@ func setGCPercent(in int32) (out int32) {
in = -1
}
gcpercent = in
heapminimum = heapminimum * uint64(gcpercent) / 100
unlock(&mheap_.lock)
return out
}
......
......@@ -432,15 +432,3 @@ func reflect_typelinks() [][]*_type {
}
return ret
}
// TODO: move back into mgc.go
func readgogc() int32 {
p := gogetenv("GOGC")
if p == "" {
return 100
}
if p == "off" {
return -1
}
return int32(atoi(p))
}
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