Prioritizing nodes based on volume capacity

pkg/controller/volume/scheduling/scheduler_binder.go

@@ -82,6 +82,28 @@ type BindingInfo struct {
 	pv *v1.PersistentVolume
 }
 
+// StorageClassName returns the name of the storage class.
+func (b *BindingInfo) StorageClassName() string {
+	return b.pv.Spec.StorageClassName
+}
+
+// VolumeResource represents volume resource.
+type VolumeResource struct {
+	Requested int64
+	Capacity  int64
+}
+
+// VolumeResource returns volume resource.
+func (b *BindingInfo) VolumeResource() *VolumeResource {
+	// both fields are mandatory
+	requestedQty := b.pvc.Spec.Resources.Requests[v1.ResourceName(v1.ResourceStorage)]
+	capacitQty := b.pv.Spec.Capacity[v1.ResourceName(v1.ResourceStorage)]
+	return &VolumeResource{
+		Requested: requestedQty.Value(),
+		Capacity:  capacitQty.Value(),
+	}
+}
+
 // PodVolumes holds pod's volumes information used in volume scheduling.
 type PodVolumes struct {
 	// StaticBindings are binding decisions for PVCs which can be bound to

pkg/scheduler/algorithmprovider/registry.go

@@ -69,7 +69,7 @@ func ListAlgorithmProviders() string {
 }
 
 func getDefaultConfig() *schedulerapi.Plugins {
-	return &schedulerapi.Plugins{
+	plugins := &schedulerapi.Plugins{
 		QueueSort: schedulerapi.PluginSet{
 			Enabled: []schedulerapi.Plugin{
 				{Name: queuesort.Name},
@@ -148,6 +148,10 @@ func getDefaultConfig() *schedulerapi.Plugins {
 			},
 		},
 	}
+	if utilfeature.DefaultFeatureGate.Enabled(features.VolumeCapacityPriority) {
+		plugins.Score.Enabled = append(plugins.Score.Enabled, schedulerapi.Plugin{Name: volumebinding.Name, Weight: 1})
+	}
+	return plugins
 }
 
 func getClusterAutoscalerConfig() *schedulerapi.Plugins {

pkg/scheduler/framework/plugins/helper/shape_score.go

@@ -0,0 +1,51 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package helper
+
+// FunctionShape represents a collection of FunctionShapePoint.
+type FunctionShape []FunctionShapePoint
+
+// FunctionShapePoint represents a shape point.
+type FunctionShapePoint struct {
+	// Utilization is function argument.
+	Utilization int64
+	// Score is function value.
+	Score int64
+}
+
+// BuildBrokenLinearFunction creates a function which is built using linear segments. Segments are defined via shape array.
+// Shape[i].Utilization slice represents points on "Utilization" axis where different segments meet.
+// Shape[i].Score represents function values at meeting points.
+//
+// function f(p) is defined as:
+//   shape[0].Score for p < f[0].Utilization
+//   shape[i].Score for p == shape[i].Utilization
+//   shape[n-1].Score for p > shape[n-1].Utilization
+// and linear between points (p < shape[i].Utilization)
+func BuildBrokenLinearFunction(shape FunctionShape) func(int64) int64 {
+	return func(p int64) int64 {
+		for i := 0; i < len(shape); i++ {
+			if p <= int64(shape[i].Utilization) {
+				if i == 0 {
+					return shape[0].Score
+				}
+				return shape[i-1].Score + (shape[i].Score-shape[i-1].Score)*(p-shape[i-1].Utilization)/(shape[i].Utilization-shape[i-1].Utilization)
+			}
+		}
+		return shape[len(shape)-1].Score
+	}
+}

pkg/scheduler/framework/plugins/noderesources/requested_to_capacity_ratio.go

@@ -26,6 +26,7 @@ import (
 	"k8s.io/kubernetes/pkg/scheduler/apis/config"
 	"k8s.io/kubernetes/pkg/scheduler/apis/config/validation"
 	"k8s.io/kubernetes/pkg/scheduler/framework"
+	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/helper"
 )
 
 const (
@@ -34,15 +35,6 @@ const (
 	maxUtilization               = 100
 )
 
-type functionShape []functionShapePoint
-
-type functionShapePoint struct {
-	// utilization is function argument.
-	utilization int64
-	// score is function value.
-	score int64
-}
-
 // NewRequestedToCapacityRatio initializes a new plugin and returns it.
 func NewRequestedToCapacityRatio(plArgs runtime.Object, handle framework.Handle) (framework.Plugin, error) {
 	args, err := getRequestedToCapacityRatioArgs(plArgs)
@@ -54,14 +46,14 @@ func NewRequestedToCapacityRatio(plArgs runtime.Object, handle framework.Handle)
 		return nil, err
 	}
 
-	shape := make([]functionShapePoint, 0, len(args.Shape))
+	shape := make([]helper.FunctionShapePoint, 0, len(args.Shape))
 	for _, point := range args.Shape {
-		shape = append(shape, functionShapePoint{
-			utilization: int64(point.Utilization),
+		shape = append(shape, helper.FunctionShapePoint{
+			Utilization: int64(point.Utilization),
 			// MaxCustomPriorityScore may diverge from the max score used in the scheduler and defined by MaxNodeScore,
 			// therefore we need to scale the score returned by requested to capacity ratio to the score range
 			// used by the scheduler.
-			score: int64(point.Score) * (framework.MaxNodeScore / config.MaxCustomPriorityScore),
+			Score: int64(point.Score) * (framework.MaxNodeScore / config.MaxCustomPriorityScore),
 		})
 	}
 
@@ -120,8 +112,8 @@ func (pl *RequestedToCapacityRatio) ScoreExtensions() framework.ScoreExtensions
 	return nil
 }
 
-func buildRequestedToCapacityRatioScorerFunction(scoringFunctionShape functionShape, resourceToWeightMap resourceToWeightMap) func(resourceToValueMap, resourceToValueMap, bool, int, int) int64 {
-	rawScoringFunction := buildBrokenLinearFunction(scoringFunctionShape)
+func buildRequestedToCapacityRatioScorerFunction(scoringFunctionShape helper.FunctionShape, resourceToWeightMap resourceToWeightMap) func(resourceToValueMap, resourceToValueMap, bool, int, int) int64 {
+	rawScoringFunction := helper.BuildBrokenLinearFunction(scoringFunctionShape)
 	resourceScoringFunction := func(requested, capacity int64) int64 {
 		if capacity == 0 || requested > capacity {
 			return rawScoringFunction(maxUtilization)
@@ -144,26 +136,3 @@ func buildRequestedToCapacityRatioScorerFunction(scoringFunctionShape functionSh
 		return int64(math.Round(float64(nodeScore) / float64(weightSum)))
 	}
 }
-
-// Creates a function which is built using linear segments. Segments are defined via shape array.
-// Shape[i].utilization slice represents points on "utilization" axis where different segments meet.
-// Shape[i].score represents function values at meeting points.
-//
-// function f(p) is defined as:
-//   shape[0].score for p < f[0].utilization
-//   shape[i].score for p == shape[i].utilization
-//   shape[n-1].score for p > shape[n-1].utilization
-// and linear between points (p < shape[i].utilization)
-func buildBrokenLinearFunction(shape functionShape) func(int64) int64 {
-	return func(p int64) int64 {
-		for i := 0; i < len(shape); i++ {
-			if p <= int64(shape[i].utilization) {
-				if i == 0 {
-					return shape[0].score
-				}
-				return shape[i-1].score + (shape[i].score-shape[i-1].score)*(p-shape[i-1].utilization)/(shape[i].utilization-shape[i-1].utilization)
-			}
-		}
-		return shape[len(shape)-1].score
-	}
-}

pkg/scheduler/framework/plugins/noderesources/requested_to_capacity_ratio_test.go

@@ -27,6 +27,7 @@ import (
 	"k8s.io/apimachinery/pkg/api/resource"
 	"k8s.io/kubernetes/pkg/scheduler/apis/config"
 	"k8s.io/kubernetes/pkg/scheduler/framework"
+	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/helper"
 	"k8s.io/kubernetes/pkg/scheduler/framework/runtime"
 	"k8s.io/kubernetes/pkg/scheduler/internal/cache"
 )
@@ -124,13 +125,13 @@ func TestBrokenLinearFunction(t *testing.T) {
 		expected int64
 	}
 	type Test struct {
-		points     []functionShapePoint
+		points     []helper.FunctionShapePoint
 		assertions []Assertion
 	}
 
 	tests := []Test{
 		{
-			points: []functionShapePoint{{10, 1}, {90, 9}},
+			points: []helper.FunctionShapePoint{{Utilization: 10, Score: 1}, {Utilization: 90, Score: 9}},
 			assertions: []Assertion{
 				{p: -10, expected: 1},
 				{p: 0, expected: 1},
@@ -147,7 +148,7 @@ func TestBrokenLinearFunction(t *testing.T) {
 			},
 		},
 		{
-			points: []functionShapePoint{{0, 2}, {40, 10}, {100, 0}},
+			points: []helper.FunctionShapePoint{{Utilization: 0, Score: 2}, {Utilization: 40, Score: 10}, {Utilization: 100, Score: 0}},
 			assertions: []Assertion{
 				{p: -10, expected: 2},
 				{p: 0, expected: 2},
@@ -160,7 +161,7 @@ func TestBrokenLinearFunction(t *testing.T) {
 			},
 		},
 		{
-			points: []functionShapePoint{{0, 2}, {40, 2}, {100, 2}},
+			points: []helper.FunctionShapePoint{{Utilization: 0, Score: 2}, {Utilization: 40, Score: 2}, {Utilization: 100, Score: 2}},
 			assertions: []Assertion{
 				{p: -10, expected: 2},
 				{p: 0, expected: 2},
@@ -176,7 +177,7 @@ func TestBrokenLinearFunction(t *testing.T) {
 
 	for i, test := range tests {
 		t.Run(fmt.Sprintf("case_%d", i), func(t *testing.T) {
-			function := buildBrokenLinearFunction(test.points)
+			function := helper.BuildBrokenLinearFunction(test.points)
 			for _, assertion := range test.assertions {
 				assert.InDelta(t, assertion.expected, function(assertion.p), 0.1, "points=%v, p=%f", test.points, assertion.p)
 			}

pkg/scheduler/framework/plugins/volumebinding/scorer.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package volumebinding
+
+import (
+	"math"
+
+	"k8s.io/kubernetes/pkg/controller/volume/scheduling"
+	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/helper"
+)
+
+type classResourceMap map[string]*scheduling.VolumeResource
+
+type volumeCapacityScorer func(classResourceMap) int64
+
+func buildScorerFunction(scoringFunctionShape helper.FunctionShape) volumeCapacityScorer {
+	rawScoringFunction := helper.BuildBrokenLinearFunction(scoringFunctionShape)
+	f := func(requested, capacity int64) int64 {
+		if capacity == 0 || requested > capacity {
+			return rawScoringFunction(maxUtilization)
+		}
+
+		return rawScoringFunction(requested * maxUtilization / capacity)
+	}
+	return func(classResources classResourceMap) int64 {
+		var nodeScore, weightSum int64
+		for _, resource := range classResources {
+			classScore := f(resource.Requested, resource.Capacity)
+			nodeScore += classScore
+			// in alpha stage, all classes have the same weight
+			weightSum += 1
+		}
+		if weightSum == 0 {
+			return 0
+		}
+		return int64(math.Round(float64(nodeScore) / float64(weightSum)))
+	}
+}

pkg/scheduler/framework/plugins/volumebinding/volume_binding.go

@@ -33,6 +33,7 @@ import (
 	"k8s.io/kubernetes/pkg/features"
 	"k8s.io/kubernetes/pkg/scheduler/apis/config"
 	"k8s.io/kubernetes/pkg/scheduler/framework"
+	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/helper"
 )
 
 const (
@@ -40,6 +41,8 @@ const (
 	DefaultBindTimeoutSeconds = 600
 
 	stateKey framework.StateKey = Name
+
+	maxUtilization = 100
 )
 
 // the state is initialized in PreFilter phase. because we save the pointer in
@@ -68,12 +71,14 @@ type VolumeBinding struct {
 	Binder                               scheduling.SchedulerVolumeBinder
 	PVCLister                            corelisters.PersistentVolumeClaimLister
 	GenericEphemeralVolumeFeatureEnabled bool
+	scorer                               volumeCapacityScorer
 }
 
 var _ framework.PreFilterPlugin = &VolumeBinding{}
 var _ framework.FilterPlugin = &VolumeBinding{}
 var _ framework.ReservePlugin = &VolumeBinding{}
 var _ framework.PreBindPlugin = &VolumeBinding{}
+var _ framework.ScorePlugin = &VolumeBinding{}
 
 // Name is the name of the plugin used in Registry and configurations.
 const Name = "VolumeBinding"
@@ -214,6 +219,54 @@ func (pl *VolumeBinding) Filter(ctx context.Context, cs *framework.CycleState, p
 	return nil
 }
 
+var (
+	// TODO (for alpha) make it configurable in config.VolumeBindingArgs
+	defaultShapePoint = []config.UtilizationShapePoint{
+		{
+			Utilization: 0,
+			Score:       0,
+		},
+		{
+			Utilization: 100,
+			Score:       int32(config.MaxCustomPriorityScore),
+		},
+	}
+)
+
+// Score invoked at the score extension point.
+func (pl *VolumeBinding) Score(ctx context.Context, cs *framework.CycleState, pod *v1.Pod, nodeName string) (int64, *framework.Status) {
+	if pl.scorer == nil {
+		return 0, nil
+	}
+	state, err := getStateData(cs)
+	if err != nil {
+		return 0, framework.AsStatus(err)
+	}
+	podVolumes, ok := state.podVolumesByNode[nodeName]
+	if !ok {
+		return 0, nil
+	}
+	// group by storage class
+	classToWeight := make(classToWeightMap)
+	requestedClassToValueMap := make(map[string]int64)
+	capacityClassToValueMap := make(map[string]int64)
+	for _, staticBinding := range podVolumes.StaticBindings {
+		class := staticBinding.StorageClassName()
+		volumeResource := staticBinding.VolumeResource()
+		if _, ok := requestedClassToValueMap[class]; !ok {
+			classToWeight[class] = 1 // in alpha stage, all classes have the same weight
+		}
+		requestedClassToValueMap[class] += volumeResource.Requested
+		capacityClassToValueMap[class] += volumeResource.Capacity
+	}
+	return pl.scorer(requestedClassToValueMap, capacityClassToValueMap, classToWeight), nil
+}
+
+// ScoreExtensions of the Score plugin.
+func (pl *VolumeBinding) ScoreExtensions() framework.ScoreExtensions {
+	return nil
+}
+
 // Reserve reserves volumes of pod and saves binding status in cycle state.
 func (pl *VolumeBinding) Reserve(ctx context.Context, cs *framework.CycleState, pod *v1.Pod, nodeName string) *framework.Status {
 	state, err := getStateData(cs)
@@ -303,10 +356,24 @@ func New(plArgs runtime.Object, fh framework.Handle) (framework.Plugin, error) {
 		}
 	}
 	binder := scheduling.NewVolumeBinder(fh.ClientSet(), podInformer, nodeInformer, csiNodeInformer, pvcInformer, pvInformer, storageClassInformer, capacityCheck, time.Duration(args.BindTimeoutSeconds)*time.Second)
+
+	// build score function
+	var scorer volumeCapacityScorer
+	if utilfeature.DefaultFeatureGate.Enabled(features.VolumeCapacityPriority) {
+		shape := make(helper.FunctionShape, 0, len(defaultShapePoint))
+		for _, point := range defaultShapePoint {
+			shape = append(shape, helper.FunctionShapePoint{
+				Utilization: int64(point.Utilization),
+				Score:       int64(point.Score) * (framework.MaxNodeScore / config.MaxCustomPriorityScore),
+			})
+		}
+		scorer = buildScorerFunction(shape)
+	}
 	return &VolumeBinding{
 		Binder:                               binder,
 		PVCLister:                            pvcInformer.Lister(),
 		GenericEphemeralVolumeFeatureEnabled: utilfeature.DefaultFeatureGate.Enabled(features.GenericEphemeralVolume),
+		scorer:                               scorer,
 	}, nil
 }