// mark time in profiles.
func gcDrainMarkWorkerIdle(gcw *gcWork) {
	gcDrain(gcw, gcDrainIdle|gcDrainUntilPreempt|gcDrainFlushBgCredit)
}

// gcDrainMarkWorkerDedicated is a wrapper for gcDrain that exists to better account
// mark time in profiles.
func gcDrainMarkWorkerDedicated(gcw *gcWork, untilPreempt bool) {
	flags := gcDrainFlushBgCredit
	if untilPreempt {
		flags |= gcDrainUntilPreempt
	}
	gcDrain(gcw, flags)

			casGToWaitingForGC(gp, _Grunning, waitReasonGCWorkerActive)
			switch pp.gcMarkWorkerMode {
			default:
				throw("gcBgMarkWorker: unexpected gcMarkWorkerMode")
			case gcMarkWorkerDedicatedMode:
				gcDrainMarkWorkerDedicated(&pp.gcw, true)
				if gp.preempt {
					// We were preempted. This is
					// a useful signal to kick
					// everything out of the run
					// queue so it can run
					// somewhere else.