runtime: minor clarifications of markroot
This puts the _Root* indexes in a more friendly order and tweaks
markrootSpans to use a for-range loop instead of its own indexing.
Change-Id: I2c18d55c9a673ea396b6424d51ef4997a1a74825
Reviewed-on: https://go-review.googlesource.com/14548
Reviewed-by: Rick Hudson <rlh@golang.org>
diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go
index 7fdd93b..848e8f6 100644
--- a/src/runtime/mgc.go
+++ b/src/runtime/mgc.go
@@ -126,13 +126,14 @@
_DebugGC = 0
_ConcurrentSweep = true
_FinBlockSize = 4 * 1024
+
_RootData = 0
_RootBss = 1
_RootFinalizers = 2
- _RootSpans0 = 3
+ _RootFlushCaches = 3
+ _RootSpans0 = 4
_RootSpansShards = 128
- _RootFlushCaches = _RootSpans0 + _RootSpansShards
- _RootCount = _RootFlushCaches + 1
+ _RootCount = _RootSpans0 + _RootSpansShards
// sweepMinHeapDistance is a lower bound on the heap distance
// (in bytes) reserved for concurrent sweeping between GC
diff --git a/src/runtime/mgcmark.go b/src/runtime/mgcmark.go
index 128a163..c8f8a66 100644
--- a/src/runtime/mgcmark.go
+++ b/src/runtime/mgcmark.go
@@ -121,8 +121,7 @@
sg := mheap_.sweepgen
startSpan := shard * len(work.spans) / _RootSpansShards
endSpan := (shard + 1) * len(work.spans) / _RootSpansShards
- for spanidx := startSpan; spanidx < endSpan; spanidx++ {
- s := work.spans[spanidx]
+ for _, s := range work.spans[startSpan:endSpan] {
if s.state != mSpanInUse {
continue
}
