gcstoptheworld: setting gcstoptheworld=1 disables concurrent garbage collection,
	making every garbage collection a stop-the-world event. Setting gcstoptheworld=2
	also disables concurrent sweeping after the garbage collection finishes.

	gctrace: setting gctrace=1 causes the garbage collector to emit a single line to standard
	error at each collection, summarizing the amount of memory collected and the

	// background mark workers.
	UtilBackground
	// UtilAssist means utilization should account for mark
	// assists.
	UtilAssist
	// UtilSweep means utilization should account for sweeping.
	UtilSweep

	// UtilPerProc means each P should be given a separate
	// utilization function. Otherwise, there is a single function
	// and each P is given a fraction of the utilization.
	UtilPerProc
)

//	   allocate a new group of pages (at least 1MB) from the
//	   operating system. Allocating a large run of pages
//	   amortizes the cost of talking to the operating system.
//
// Sweeping an mspan and freeing objects on it proceeds up a similar
// hierarchy:
//
//	1. If the mspan is being swept in response to allocation, it
//	   is returned to the mcache to satisfy the allocation.
//

	// has actually been swept.
	maySweep bool

	// inSweep indicates that at least one sweep event has been traced.
	inSweep bool

	// swept and reclaimed track the number of bytes swept and reclaimed
	// by sweeping in the current sweep loop (while maySweep was true).
	swept, reclaimed uintptr
}

// traceLockInit initializes global trace locks.
func traceLockInit() {

			if *evp == nil {
				return fmt.Errorf("bogus STW end (time %d)", ev.Ts)
			}
			*evp = nil
		case EvGCSweepStart:
			p := ps[ev.P]
			if p.evSweep != nil {
				return fmt.Errorf("previous sweeping is not ended before a new one (time %d)", ev.Ts)
			}
			p.evSweep = ev

			ps[ev.P] = p
		case EvGCMarkAssistStart:
			g := gs[ev.G]
			if g.evMarkAssist != nil {

// To add a new feature, define a key for it above and add it here. The features will be
// available throughout Kubernetes binaries.
//
// Entries are separated from each other with blank lines to avoid sweeping gofmt changes
// when adding or removing one entry.
var defaultKubernetesFeatureGates = map[featuregate.Feature]featuregate.FeatureSpec{
	CrossNamespaceVolumeDataSource: {Default: false, PreRelease: featuregate.Alpha},

	// It's OK to set it here because (1) a GC isn't in progress, so the scanning code
	// won't make a bad decision, (2) we're currently non-preemptible and in the runtime,
	// so a GC is blocked from starting. We might race with sweeping, which could
	// put it on the "wrong" sweep list, but really don't care because the chunk is
	// treated as a large object span and there's no meaningful difference between scan

}

func (o *ordering) advanceGCSweepActive(ev *baseEvent, evt *evTable, m ThreadID, gen uint64, curCtx schedCtx) (schedCtx, bool, error) {
	pid := ProcID(ev.args[0])
	// N.B. In practice Ps can't block while they're sweeping, so this can only
	// ever reference curCtx.P. However, be lenient about this like we are with
	// GCMarkAssistActive; there's no reason the runtime couldn't change to block
	// in the middle of a sweep.

// by the os/signal package.
//
//go:linkname signalWaitUntilIdle os/signal.signalWaitUntilIdle
func signalWaitUntilIdle() {
	for {
		lock(&sig.lock)
		sleeping := sig.sleeping
		unlock(&sig.lock)
		if sleeping {
			return
		}
		Gosched()
	}
}

// Must only be called from a single goroutine at a time.
//
//go:linkname signal_enable os/signal.signal_enable

//		If any procs are sleeping on addr, wake up at most cnt.

const (
	mutex_unlocked = 0
	mutex_locked   = 1
	mutex_sleeping = 2

	active_spin     = 4
	active_spin_cnt = 30
	passive_spin    = 1
)

// Possible lock states are mutex_unlocked, mutex_locked and mutex_sleeping.
// mutex_sleeping means that there is presumably at least one sleeping thread.