runtime: expand comment on work.spans

Change-Id: I4b8a6f5d9bc5aba16026d17f99f3512dacde8d2d Reviewed-on: https://go-review.googlesource.com/30534 Run-TryBot: Austin Clements <austin@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Rick Hudson <rlh@golang.org>
golang · Oct 25, 2016 · 45baff6 · 45baff6
1 parent 5915ce6
commit 45baff6
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go
@@ -815,7 +815,9 @@ var work struct {
 	// mode is the concurrency mode of the current GC cycle.
 	mode gcMode
 
-	// Copy of mheap.allspans for marker or sweeper.
+	// Snapshot of mheap.allspans for marker or sweeper created by
+	// gcCopySpans. Unlike allspans, this does not change except
+	// at controlled GC transition points.
 	spans []*mspan
 
 	// totaltime is the CPU nanoseconds spent in GC since the