Scheduler first fit (#123384)

* Don't evaluate extra nodes if there's no score plugin defined

* Fix existing unit test (add no op scoring plugin)

* Add unit tests for no score plugin scenario

* address review comments

* add a test with non-filter, non-scoring extender

pkg/scheduler/extender.go

@@ -383,6 +383,16 @@ func (h *HTTPExtender) IsBinder() bool {
 	return h.bindVerb != ""
 }
 
+// IsPrioritizer returns whether this extender is configured for the Prioritize method.
+func (h *HTTPExtender) IsPrioritizer() bool {
+	return h.prioritizeVerb != ""
+}
+
+// IsFilter returns whether this extender is configured for the Filter method.
+func (h *HTTPExtender) IsFilter() bool {
+	return h.filterVerb != ""
+}
+
 // Helper function to send messages to the extender
 func (h *HTTPExtender) send(action string, args interface{}, result interface{}) error {
 	out, err := json.Marshal(args)

pkg/scheduler/extender_test.go

@@ -93,6 +93,7 @@ func TestSchedulerWithExtenders(t *testing.T) {
 			registerPlugins: []tf.RegisterPluginFunc{
 				tf.RegisterFilterPlugin("TrueFilter", tf.NewTrueFilterPlugin),
 				tf.RegisterQueueSortPlugin(queuesort.Name, queuesort.New),
+				tf.RegisterScorePlugin("EqualPrioritizerPlugin", tf.NewEqualPrioritizerPlugin(), 1),
 				tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
 			},
 			extenders: []tf.FakeExtender{
@@ -245,6 +246,7 @@ func TestSchedulerWithExtenders(t *testing.T) {
 			// because of the errors from errorPredicateExtender.
 			registerPlugins: []tf.RegisterPluginFunc{
 				tf.RegisterFilterPlugin("TrueFilter", tf.NewTrueFilterPlugin),
+				tf.RegisterScorePlugin("EqualPrioritizerPlugin", tf.NewEqualPrioritizerPlugin(), 1),
 				tf.RegisterQueueSortPlugin(queuesort.Name, queuesort.New),
 				tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
 			},
@@ -268,6 +270,49 @@ func TestSchedulerWithExtenders(t *testing.T) {
 			},
 			name: "test 9",
 		},
+		{
+			registerPlugins: []tf.RegisterPluginFunc{
+				tf.RegisterFilterPlugin("TrueFilter", tf.NewTrueFilterPlugin),
+				tf.RegisterQueueSortPlugin(queuesort.Name, queuesort.New),
+				tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
+			},
+			extenders: []tf.FakeExtender{
+				{
+					ExtenderName: "FakeExtender1",
+					Predicates:   []tf.FitPredicate{tf.TruePredicateExtender},
+				},
+				{
+					ExtenderName: "FakeExtender2",
+					Predicates:   []tf.FitPredicate{tf.Node1PredicateExtender},
+				},
+			},
+			nodes: []string{"node1", "node2"},
+			expectedResult: ScheduleResult{
+				SuggestedHost:  "node1",
+				EvaluatedNodes: 2,
+				FeasibleNodes:  1,
+			},
+			name: "test 10 - no scoring, extender filters configured, multiple feasible nodes are evaluated",
+		},
+		{
+			registerPlugins: []tf.RegisterPluginFunc{
+				tf.RegisterQueueSortPlugin(queuesort.Name, queuesort.New),
+				tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
+			},
+			extenders: []tf.FakeExtender{
+				{
+					ExtenderName: "FakeExtender1",
+					Binder:       func() error { return nil },
+				},
+			},
+			nodes: []string{"node1", "node2"},
+			expectedResult: ScheduleResult{
+				SuggestedHost:  "node1",
+				EvaluatedNodes: 1,
+				FeasibleNodes:  1,
+			},
+			name: "test 11 - no scoring, no prefilters or  extender filters configured, a single feasible node is evaluated",
+		},
 	}
 
 	for _, test := range tests {

pkg/scheduler/framework/extender.go

@@ -50,6 +50,12 @@ type Extender interface {
 	// this pod is managed by this extender.
 	IsInterested(pod *v1.Pod) bool
 
+	// IsPrioritizer returns whether this extender is configured for the Prioritize method.
+	IsPrioritizer() bool
+
+	// IsFilter returns whether this extender is configured for the Filter method.
+	IsFilter() bool
+
 	// ProcessPreemption returns nodes with their victim pods processed by extender based on
 	// given:
 	//   1. Pod to schedule

pkg/scheduler/schedule_one.go

@@ -546,6 +546,29 @@ func (sched *Scheduler) evaluateNominatedNode(ctx context.Context, pod *v1.Pod,
 	return feasibleNodes, nil
 }
 
+// hasScoring checks if scoring nodes is configured.
+func (sched *Scheduler) hasScoring(fwk framework.Framework) bool {
+	if fwk.HasScorePlugins() {
+		return true
+	}
+	for _, extender := range sched.Extenders {
+		if extender.IsPrioritizer() {
+			return true
+		}
+	}
+	return false
+}
+
+// hasExtenderFilters checks if any extenders filter nodes.
+func (sched *Scheduler) hasExtenderFilters() bool {
+	for _, extender := range sched.Extenders {
+		if extender.IsFilter() {
+			return true
+		}
+	}
+	return false
+}
+
 // findNodesThatPassFilters finds the nodes that fit the filter plugins.
 func (sched *Scheduler) findNodesThatPassFilters(
 	ctx context.Context,
@@ -556,6 +579,9 @@ func (sched *Scheduler) findNodesThatPassFilters(
 	nodes []*framework.NodeInfo) ([]*framework.NodeInfo, error) {
 	numAllNodes := len(nodes)
 	numNodesToFind := sched.numFeasibleNodesToFind(fwk.PercentageOfNodesToScore(), int32(numAllNodes))
+	if !sched.hasExtenderFilters() && !sched.hasScoring(fwk) {
+		numNodesToFind = 1
+	}
 
 	// Create feasible list with enough space to avoid growing it
 	// and allow assigning.

pkg/scheduler/schedule_one_test.go

@@ -92,6 +92,8 @@ type fakeExtender struct {
 	ignorable         bool
 	gotBind           bool
 	errBind           bool
+	isPrioritizer     bool
+	isFilter          bool
 }
 
 func (f *fakeExtender) Name() string {
@@ -144,6 +146,14 @@ func (f *fakeExtender) IsInterested(pod *v1.Pod) bool {
 	return pod != nil && pod.Name == f.interestedPodName
 }
 
+func (f *fakeExtender) IsPrioritizer() bool {
+	return f.isPrioritizer
+}
+
+func (f *fakeExtender) IsFilter() bool {
+	return f.isFilter
+}
+
 type falseMapPlugin struct{}
 
 func newFalseMapPlugin() frameworkruntime.PluginFactory {
@@ -1823,6 +1833,7 @@ func TestSchedulerSchedulePod(t *testing.T) {
 			registerPlugins: []tf.RegisterPluginFunc{
 				tf.RegisterQueueSortPlugin(queuesort.Name, queuesort.New),
 				tf.RegisterFilterPlugin("TrueFilter", tf.NewTrueFilterPlugin),
+				tf.RegisterScorePlugin("EqualPrioritizerPlugin", tf.NewEqualPrioritizerPlugin(), 1),
 				tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
 			},
 			nodes:     []string{"node1", "node2"},
@@ -1940,6 +1951,7 @@ func TestSchedulerSchedulePod(t *testing.T) {
 				tf.RegisterQueueSortPlugin(queuesort.Name, queuesort.New),
 				tf.RegisterPreFilterPlugin(volumebinding.Name, frameworkruntime.FactoryAdapter(fts, volumebinding.New)),
 				tf.RegisterFilterPlugin("TrueFilter", tf.NewTrueFilterPlugin),
+				tf.RegisterScorePlugin("EqualPrioritizerPlugin", tf.NewEqualPrioritizerPlugin(), 1),
 				tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
 			},
 			nodes: []string{"node1", "node2"},
@@ -2053,6 +2065,7 @@ func TestSchedulerSchedulePod(t *testing.T) {
 					"PreFilter",
 					"Filter",
 				),
+				tf.RegisterScorePlugin("EqualPrioritizerPlugin", tf.NewEqualPrioritizerPlugin(), 1),
 				tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
 			},
 			nodes: []string{"node1", "node2", "node3"},
@@ -2355,6 +2368,7 @@ func TestSchedulerSchedulePod(t *testing.T) {
 						},
 					}, nil
 				}, "PreFilter", "Filter"),
+				tf.RegisterScorePlugin("EqualPrioritizerPlugin", tf.NewEqualPrioritizerPlugin(), 1),
 				tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
 			},
 			nodes:              []string{"node1", "node2", "node3"},
@@ -2377,6 +2391,33 @@ func TestSchedulerSchedulePod(t *testing.T) {
 			pod:       st.MakePod().Name("ignore").UID("ignore").Obj(),
 			wantNodes: sets.New("node1", "node2"),
 		},
+		{
+			name: "test without score plugin no extra nodes are evaluated",
+			registerPlugins: []tf.RegisterPluginFunc{
+				tf.RegisterQueueSortPlugin(queuesort.Name, queuesort.New),
+				tf.RegisterFilterPlugin("TrueFilter", tf.NewTrueFilterPlugin),
+				tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
+			},
+			nodes:              []string{"node1", "node2", "node3"},
+			pod:                st.MakePod().Name("pod1").UID("pod1").Obj(),
+			wantNodes:          sets.New("node1", "node2", "node3"),
+			wantEvaluatedNodes: ptr.To[int32](1),
+		},
+		{
+			name: "test no score plugin, prefilter plugin returning 2 nodes",
+			registerPlugins: []tf.RegisterPluginFunc{
+				tf.RegisterQueueSortPlugin(queuesort.Name, queuesort.New),
+				tf.RegisterPreFilterPlugin(
+					"FakePreFilter",
+					tf.NewFakePreFilterPlugin("FakePreFilter", &framework.PreFilterResult{NodeNames: sets.New("node1", "node2")}, nil),
+				),
+				tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
+			},
+			nodes:              []string{"node1", "node2", "node3"},
+			pod:                st.MakePod().Name("test-prefilter").UID("test-prefilter").Obj(),
+			wantNodes:          sets.New("node1", "node2"),
+			wantEvaluatedNodes: ptr.To[int32](2),
+		},
 	}
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
@@ -3249,6 +3290,7 @@ func TestFairEvaluationForNodes(t *testing.T) {
 		[]tf.RegisterPluginFunc{
 			tf.RegisterQueueSortPlugin(queuesort.Name, queuesort.New),
 			tf.RegisterFilterPlugin("TrueFilter", tf.NewTrueFilterPlugin),
+			tf.RegisterScorePlugin("EqualPrioritizerPlugin", tf.NewEqualPrioritizerPlugin(), 1),
 			tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
 		},
 		"",
@@ -3327,6 +3369,7 @@ func TestPreferNominatedNodeFilterCallCounts(t *testing.T) {
 			registerPlugins := []tf.RegisterPluginFunc{
 				tf.RegisterQueueSortPlugin(queuesort.Name, queuesort.New),
 				registerFakeFilterFunc,
+				tf.RegisterScorePlugin("EqualPrioritizerPlugin", tf.NewEqualPrioritizerPlugin(), 1),
 				tf.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
 			}
 			fwk, err := tf.NewFramework(

pkg/scheduler/testing/framework/fake_extender.go

@@ -149,6 +149,7 @@ type FakeExtender struct {
 	FilteredNodes    []*framework.NodeInfo
 	UnInterested     bool
 	Ignorable        bool
+	Binder           func() error
 
 	// Cached node information for fake extender
 	CachedNodeNameToInfo map[string]*framework.NodeInfo
@@ -361,6 +362,9 @@ func (f *FakeExtender) Prioritize(pod *v1.Pod, nodes []*framework.NodeInfo) (*ex
 
 // Bind implements the extender Bind function.
 func (f *FakeExtender) Bind(binding *v1.Binding) error {
+	if f.Binder != nil {
+		return f.Binder()
+	}
 	if len(f.FilteredNodes) != 0 {
 		for _, node := range f.FilteredNodes {
 			if node.Node().Name == binding.Target.Name {
@@ -380,6 +384,16 @@ func (f *FakeExtender) IsBinder() bool {
 	return true
 }
 
+// IsPrioritizer returns true if there are any prioritizers.
+func (f *FakeExtender) IsPrioritizer() bool {
+	return len(f.Prioritizers) > 0
+}
+
+// IsFilter returns true if there are any filters.
+func (f *FakeExtender) IsFilter() bool {
+	return len(f.Predicates) > 0
+}
+
 // IsInterested returns a bool indicating whether this extender is interested in this Pod.
 func (f *FakeExtender) IsInterested(pod *v1.Pod) bool {
 	return !f.UnInterested

pkg/scheduler/testing/framework/fake_plugins.go

@@ -280,3 +280,13 @@ func NewFakePreScoreAndScorePlugin(name string, score int64, preScoreStatus, sco
 		}, nil
 	}
 }
+
+// NewEqualPrioritizerPlugin returns a factory function to build equalPrioritizerPlugin.
+func NewEqualPrioritizerPlugin() frameworkruntime.PluginFactory {
+	return func(_ context.Context, _ runtime.Object, _ framework.Handle) (framework.Plugin, error) {
+		return &FakePreScoreAndScorePlugin{
+			name:  "EqualPrioritizerPlugin",
+			score: 1,
+		}, nil
+	}
+}