From 199dc03bdd4c739c234cd6e13d5b58919b674554 Mon Sep 17 00:00:00 2001
From: Aleksandra Malinowska <aleksandram@google.com>
Date: Mon, 27 Nov 2023 09:50:57 +0100
Subject: [PATCH] Don't evaluate extra nodes if there's no score plugin defined

---
 pkg/scheduler/extender.go                        |  5 +++++
 pkg/scheduler/framework/extender.go              |  3 +++
 pkg/scheduler/schedule_one.go                    | 16 ++++++++++++++++
 pkg/scheduler/schedule_one_test.go               |  5 +++++
 pkg/scheduler/testing/framework/fake_extender.go |  5 +++++
 5 files changed, 34 insertions(+)

diff --git a/pkg/scheduler/extender.go b/pkg/scheduler/extender.go
index 7ccb9e6ca69..932c98ccfee 100644
--- a/pkg/scheduler/extender.go
+++ b/pkg/scheduler/extender.go
@@ -382,6 +382,11 @@ 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 != ""
+}
+
 // Helper function to send messages to the extender
 func (h *HTTPExtender) send(action string, args interface{}, result interface{}) error {
 	out, err := json.Marshal(args)
diff --git a/pkg/scheduler/framework/extender.go b/pkg/scheduler/framework/extender.go
index d47c89bf1e4..1f1b67ad3b0 100644
--- a/pkg/scheduler/framework/extender.go
+++ b/pkg/scheduler/framework/extender.go
@@ -50,6 +50,9 @@ 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
+
 	// ProcessPreemption returns nodes with their victim pods processed by extender based on
 	// given:
 	//   1. Pod to schedule
diff --git a/pkg/scheduler/schedule_one.go b/pkg/scheduler/schedule_one.go
index b9ded88732c..753eab6c14e 100644
--- a/pkg/scheduler/schedule_one.go
+++ b/pkg/scheduler/schedule_one.go
@@ -527,6 +527,19 @@ 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
+}
+
 // findNodesThatPassFilters finds the nodes that fit the filter plugins.
 func (sched *Scheduler) findNodesThatPassFilters(
 	ctx context.Context,
@@ -537,6 +550,9 @@ func (sched *Scheduler) findNodesThatPassFilters(
 	nodes []*framework.NodeInfo) ([]*v1.Node, error) {
 	numAllNodes := len(nodes)
 	numNodesToFind := sched.numFeasibleNodesToFind(fwk.PercentageOfNodesToScore(), int32(numAllNodes))
+	if !sched.hasScoring(fwk) {
+		numNodesToFind = 1
+	}
 
 	// Create feasible list with enough space to avoid growing it
 	// and allow assigning.
diff --git a/pkg/scheduler/schedule_one_test.go b/pkg/scheduler/schedule_one_test.go
index 9a70a62921a..655b3f0ae15 100644
--- a/pkg/scheduler/schedule_one_test.go
+++ b/pkg/scheduler/schedule_one_test.go
@@ -91,6 +91,7 @@ type fakeExtender struct {
 	interestedPodName string
 	ignorable         bool
 	gotBind           bool
+	isPrioritizer     bool
 }
 
 func (f *fakeExtender) Name() string {
@@ -140,6 +141,10 @@ func (f *fakeExtender) IsInterested(pod *v1.Pod) bool {
 	return pod != nil && pod.Name == f.interestedPodName
 }
 
+func (f *fakeExtender) IsPrioritizer() bool {
+	return f.isPrioritizer
+}
+
 type falseMapPlugin struct{}
 
 func newFalseMapPlugin() frameworkruntime.PluginFactory {
diff --git a/pkg/scheduler/testing/framework/fake_extender.go b/pkg/scheduler/testing/framework/fake_extender.go
index 8e1575dd365..82f9836b47f 100644
--- a/pkg/scheduler/testing/framework/fake_extender.go
+++ b/pkg/scheduler/testing/framework/fake_extender.go
@@ -380,6 +380,11 @@ 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
+}
+
 // IsInterested returns a bool indicating whether this extender is interested in this Pod.
 func (f *FakeExtender) IsInterested(pod *v1.Pod) bool {
 	return !f.UnInterested