// We will only check <candidates> with extenders that support preemption.
// Extenders which do not support preemption may later prevent preemptor from being scheduled on the nominated
// node. In that case, scheduler will find a different host for the preemptor in subsequent scheduling cycles.

// stack bound to a value that will cause the next stack bound check
// to fail and enter the stack growth implementation, which will
// detect that it was actually a preemption and redirect to preemption
// handling.
//
// Preemption at asynchronous safe-points is implemented by suspending
// the thread using an OS mechanism (e.g., signals) and inspecting its
// state to determine if the goroutine was at an asynchronous

			},
			wantResult: framework.NewPostFilterResultWithNominatedNode(""),
			wantStatus: framework.NewStatus(framework.Unschedulable, "preemption: 0/1 nodes are available: 1 No preemption victims found for incoming pod."),
		},
		{
			name: "preemption should respect filteredNodesStatuses",
			pod:  st.MakePod().Name("p").UID("p").Namespace(v1.NamespaceDefault).Priority(highPriority).Obj(),
			pods: []*v1.Pod{

// Package exithook provides limited support for on-exit cleanup.
//
// CAREFUL! The expectation is that Add should only be called
// from a safe context (e.g. not an error/panic path or signal
// handler, preemption enabled, allocation allowed, write barriers
// allowed, etc), and that the exit function F will be invoked under
// similar circumstances. That is the say, we are expecting that F

	// NodeInfoSnapshot because we don't guarantee that they will be the same.
	// For example, during preemption, we may pass a copy of the original
	// nodeInfo object that has some pods removed from it to evaluate the
	// possibility of preempting them to schedule the target pod.
	Filter(ctx context.Context, state *CycleState, pod *v1.Pod, nodeInfo *NodeInfo) *Status
}

  # Configure this to a higher priority class in order to make sure your Istio gateway pods
  # will not be killed because of low priority class.
  # Refer to https://kubernetes.io/docs/concepts/configuration/pod-priority-preemption/#priorityclass
  # for more detail.

	// saved by entersyscall here.
	entersyscall()

	// Tell asynchronous preemption that we're entering external
	// code. We do this after entersyscall because this may block
	// and cause an async preemption to fail, but at this point a
	// sync preemption will succeed (though this is not a matter
	// of correctness).
	osPreemptExtEnter(mp)

	mp.incgo = true

		}
	}

	// Mark the victim cache as empty for future gets don't bother
	// with it.
	atomic.StoreUintptr(&p.victimSize, 0)

	return nil
}

// pin pins the current goroutine to P, disables preemption and
// returns poolLocal pool for the P and the P's id.
// Caller must call runtime_procUnpin() when done with the pool.
func (p *Pool) pin() (*poolLocal, int) {
	// Check whether p is nil to get a panic.

		// Preemption must not occur here, or another G might see
		// p.gcMarkWorkerMode.

		// Disable preemption so we can use the gcw. If the
		// scheduler wants to preempt us, we'll stop draining,
		// dispose the gcw, and then preempt.
		node.m.set(acquirem())
		pp := gp.m.p.ptr() // P can't change with preemption disabled.

		if gcBlackenEnabled == 0 {

	vdsoPC uintptr // PC for traceback while in VDSO call

	// preemptGen counts the number of completed preemption
	// signals. This is used to detect when a preemption is
	// requested, but fails.
	preemptGen atomic.Uint32

	// Whether this is a pending preemption signal on this M.
	signalPending atomic.Uint32

	// pcvalue lookup cache
	pcvalueCache pcvalueCache