runtime: remove write-only sweepdata fields

Change-Id: Ia238889a704812473b838b20efedfe9d24b1e26f
Reviewed-on: https://go-review.googlesource.com/c/go/+/534160
Auto-Submit: Michael Pratt <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>

Author: prattmic

src/runtime/mgc.go

@@ -476,7 +476,6 @@ func GC() {
 	// as part of tests and benchmarks to get the system into a
 	// relatively stable and isolated state.
 	for work.cycles.Load() == n+1 && sweepone() != ^uintptr(0) {
-		sweep.nbgsweep++
 		Gosched()
 	}
 
@@ -620,7 +619,6 @@ func gcStart(trigger gcTrigger) {
 	// We check the transition condition continuously here in case
 	// this G gets delayed in to the next GC cycle.
 	for trigger.test() && sweepone() != ^uintptr(0) {
-		sweep.nbgsweep++
 	}
 
 	// Perform GC initialization and the sweep termination
@@ -1047,10 +1045,6 @@ func gcMarkTermination() {
 	// Reset idle time stat.
 	sched.idleTime.Store(0)
 
-	// Reset sweep state.
-	sweep.nbgsweep = 0
-	sweep.npausesweep = 0
-
 	if work.userForced {
 		memstats.numforcedgc++
 	}
@@ -1589,7 +1583,6 @@ func gcSweep(mode gcMode) bool {
 		}
 		// Sweep all spans eagerly.
 		for sweepone() != ^uintptr(0) {
-			sweep.npausesweep++
 		}
 		// Free workbufs eagerly.
 		prepareFreeWorkbufs()

src/runtime/mgcsweep.go

@@ -37,9 +37,6 @@ type sweepdata struct {
 	g      *g
 	parked bool
 
-	nbgsweep    uint32
-	npausesweep uint32
-
 	// active tracks outstanding sweepers and the sweep
 	// termination condition.
 	active activeSweep
@@ -237,7 +234,6 @@ func finishsweep_m() {
 	// instantly. If GC was forced before the concurrent sweep
 	// finished, there may be spans to sweep.
 	for sweepone() != ^uintptr(0) {
-		sweep.npausesweep++
 	}
 
 	// Make sure there aren't any outstanding sweepers left.
@@ -299,7 +295,6 @@ func bgsweep(c chan int) {
 		const sweepBatchSize = 10
 		nSwept := 0
 		for sweepone() != ^uintptr(0) {
-			sweep.nbgsweep++
 			nSwept++
 			if nSwept%sweepBatchSize == 0 {
 				goschedIfBusy()