return true // root scan work available
	}
	return false
}

// gcMark runs the mark (or, for concurrent GC, mark termination)
// All gcWork caches must be empty.
// STW is in effect at this point.
func gcMark(startTime int64) {
	if gcphase != _GCmarktermination {
		throw("in gcMark expecting to see gcphase as _GCmarktermination")
	}
	work.tstart = startTime

//
// Preemption must be disabled (because this uses a gcWork).
//
// Returns the amount of GC work credit produced by the operation.
// If flushBgCredit is true, then that credit is also flushed
// to the background credit pool.
//
// nowritebarrier is only advisory here.
//
//go:nowritebarrier
func markroot(gcw *gcWork, i uint32, flushBgCredit bool) int64 {

		{"block", []string{"runtime.chanrecv1", "runtime/pprof.blockChanDeep"}},
		{"mutex", []string{"sync.(*Mutex).Unlock", "runtime/pprof.blockMutexDeep"}},
		{"goroutine", []string{"runtime.gopark", "runtime.chanrecv", "runtime.chanrecv1", "runtime/pprof.goroutineDeep"}},
	}

	for _, test := range tests {
		t.Run(test.profiler, func(t *testing.T) {
			var buf bytes.Buffer

	// of time we worked, and the sleepRatio.
	sleepTime := int64(worked / s.sleepRatio)

	var slept int64
	if s.sleepStub == nil {
		// Set the timer.
		//
		// This must happen here instead of inside gopark
		// because we can't close over any variables without
		// failing escape analysis.
		start := nanotime()
		s.timer.reset(start+sleepTime, 0)

		// Mark ourselves as asleep and go to sleep.
		s.parked = true

//
// This only happens the first time a span is allocated from
// mheap.spanalloc (it is not called when a span is reused).
//
// Write barriers are disallowed here because it can be called from
// gcWork when allocating new workbufs. However, because it's an
// indirect call from the fixalloc initializer, the compiler can't see
// this.
//
// The heap lock must be held.
//
//go:nowritebarrierrec