Configurable difference ratios

cluster-autoscaler/config/autoscaling_options.go

@@ -46,6 +46,33 @@ type NodeGroupAutoscalingOptions struct {
 	ScaleDownUnreadyTime time.Duration
 }
 
+const (
+	// DefaultMaxAllocatableDifferenceRatio describes how Node.Status.Allocatable can differ between groups in the same NodeGroupSet
+	DefaultMaxAllocatableDifferenceRatio = 0.05
+	// DefaultMaxFreeDifferenceRatio describes how free resources (allocatable - daemon and system pods)
+	DefaultMaxFreeDifferenceRatio = 0.05
+	// DefaultMaxCapacityMemoryDifferenceRatio describes how Node.Status.Capacity.Memory
+	DefaultMaxCapacityMemoryDifferenceRatio = 0.015
+)
+
+// NodeGroupDifferenceRatios contains various ratios used to determine if two NodeGroups are similar and makes scaling decisions
+type NodeGroupDifferenceRatios struct {
+	// MaxAllocatableDifferenceRatio describes how Node.Status.Allocatable can differ between groups in the same NodeGroupSet
+	MaxAllocatableDifferenceRatio float64
+	// MaxFreeDifferenceRatio describes how free resources (allocatable - daemon and system pods) can differ between groups in the same NodeGroupSet
+	MaxFreeDifferenceRatio float64
+	// MaxCapacityMemoryDifferenceRatio describes how Node.Status.Capacity.Memory can differ between groups in the same NodeGroupSetAutoscalingOptions
+	MaxCapacityMemoryDifferenceRatio float64
+}
+
+func NewDefaultNodeGroupDifferenceRatios() NodeGroupDifferenceRatios {
+	return NodeGroupDifferenceRatios{
+		MaxAllocatableDifferenceRatio:    DefaultMaxAllocatableDifferenceRatio,
+		MaxFreeDifferenceRatio:           DefaultMaxFreeDifferenceRatio,
+		MaxCapacityMemoryDifferenceRatio: DefaultMaxCapacityMemoryDifferenceRatio,
+	}
+}
+
 // AutoscalingOptions contain various options to customize how autoscaling works
 type AutoscalingOptions struct {
 	// NodeGroupDefaults are default values for per NodeGroup options.
@@ -213,4 +240,6 @@ type AutoscalingOptions struct {
 	NodeDeleteDelayAfterTaint time.Duration
 	// ParallelDrain is whether CA can drain nodes in parallel.
 	ParallelDrain bool
+	// NodeGroupSetRatio is a collection of ratios used by CA used to make scaling decisions.
+	NodeGroupSetRatios NodeGroupDifferenceRatios
 }

cluster-autoscaler/core/test/common.go

@@ -140,7 +140,7 @@ func NewTestProcessors(context *context.AutoscalingContext) *processors.Autoscal
 			podlistprocessor.NewFilterOutSchedulablePodListProcessor(context.PredicateChecker),
 		),
 		NodeGroupListProcessor: &nodegroups.NoOpNodeGroupListProcessor{},
-		NodeGroupSetProcessor:  nodegroupset.NewDefaultNodeGroupSetProcessor([]string{}),
+		NodeGroupSetProcessor:  nodegroupset.NewDefaultNodeGroupSetProcessor([]string{}, config.NodeGroupDifferenceRatios{}),
 		ScaleDownSetProcessor:  nodes.NewPostFilteringScaleDownNodeProcessor(),
 		// TODO(bskiba): change scale up test so that this can be a NoOpProcessor
 		ScaleUpStatusProcessor:     &status.EventingScaleUpStatusProcessor{},

cluster-autoscaler/main.go

@@ -213,6 +213,9 @@ var (
 	nodeDeleteDelayAfterTaint          = flag.Duration("node-delete-delay-after-taint", 5*time.Second, "How long to wait before deleting a node after tainting it")
 	scaleDownSimulationTimeout         = flag.Duration("scale-down-simulation-timeout", 5*time.Minute, "How long should we run scale down simulation.")
 	parallelDrain                      = flag.Bool("parallel-drain", false, "Whether to allow parallel drain of nodes.")
+	maxCapacityMemoryDifferenceRatio   = flag.Float64("memory-difference-ratio", config.DefaultMaxCapacityMemoryDifferenceRatio, "Maximum difference in memory capacity between two similar node groups to be considered for balancing. Value is a ratio of the smaller node group's memory capacity.")
+	maxFreeDifferenceRatio             = flag.Float64("max-free-difference-ratio", config.DefaultMaxFreeDifferenceRatio, "Maximum difference in free resources between two similar node groups to be considered for balancing. Value is a ratio of the smaller node group's free resource.")
+	maxAllocatableDifferenceRatio      = flag.Float64("max-allocatable-difference-ratio", config.DefaultMaxAllocatableDifferenceRatio, "Maximum difference in allocatable resources between two similar node groups to be considered for balancing. Value is a ratio of the smaller node group's allocatable resource.")
 )
 
 func createAutoscalingOptions() config.AutoscalingOptions {
@@ -314,6 +317,11 @@ func createAutoscalingOptions() config.AutoscalingOptions {
 		NodeDeleteDelayAfterTaint:          *nodeDeleteDelayAfterTaint,
 		ScaleDownSimulationTimeout:         *scaleDownSimulationTimeout,
 		ParallelDrain:                      *parallelDrain,
+		NodeGroupSetRatios: config.NodeGroupDifferenceRatios{
+			MaxCapacityMemoryDifferenceRatio: *maxCapacityMemoryDifferenceRatio,
+			MaxAllocatableDifferenceRatio:    *maxAllocatableDifferenceRatio,
+			MaxFreeDifferenceRatio:           *maxFreeDifferenceRatio,
+		},
 	}
 }
 
@@ -395,7 +403,7 @@ func buildAutoscaler(debuggingSnapshotter debuggingsnapshot.DebuggingSnapshotter
 		} else if autoscalingOptions.CloudProviderName == cloudprovider.ClusterAPIProviderName {
 			nodeInfoComparatorBuilder = nodegroupset.CreateClusterAPINodeInfoComparator
 		}
-		nodeInfoComparator = nodeInfoComparatorBuilder(autoscalingOptions.BalancingExtraIgnoredLabels)
+		nodeInfoComparator = nodeInfoComparatorBuilder(autoscalingOptions.BalancingExtraIgnoredLabels, autoscalingOptions.NodeGroupSetRatios)
 	}
 
 	opts.Processors.NodeGroupSetProcessor = &nodegroupset.BalancingNodeGroupSetProcessor{

cluster-autoscaler/processors/nodegroupset/aws_nodegroups.go

@@ -17,13 +17,14 @@ limitations under the License.
 package nodegroupset
 
 import (
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	schedulerframework "k8s.io/kubernetes/pkg/scheduler/framework"
 )
 
 // CreateAwsNodeInfoComparator returns a comparator that checks if two nodes should be considered
 // part of the same NodeGroupSet. This is true if they match usual conditions checked by IsCloudProviderNodeInfoSimilar,
 // even if they have different AWS-specific labels.
-func CreateAwsNodeInfoComparator(extraIgnoredLabels []string) NodeInfoComparator {
+func CreateAwsNodeInfoComparator(extraIgnoredLabels []string, ratioOpts config.NodeGroupDifferenceRatios) NodeInfoComparator {
 	awsIgnoredLabels := map[string]bool{
 		"alpha.eksctl.io/instance-id":    true, // this is a label used by eksctl to identify instances.
 		"alpha.eksctl.io/nodegroup-name": true, // this is a label used by eksctl to identify "node group" names.
@@ -42,6 +43,6 @@ func CreateAwsNodeInfoComparator(extraIgnoredLabels []string) NodeInfoComparator
 	}
 
 	return func(n1, n2 *schedulerframework.NodeInfo) bool {
-		return IsCloudProviderNodeInfoSimilar(n1, n2, awsIgnoredLabels)
+		return IsCloudProviderNodeInfoSimilar(n1, n2, awsIgnoredLabels, ratioOpts)
 	}
 }

cluster-autoscaler/processors/nodegroupset/aws_nodegroups_test.go

@@ -19,12 +19,13 @@ package nodegroupset
 import (
 	"testing"
 
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	"k8s.io/autoscaler/cluster-autoscaler/context"
 	. "k8s.io/autoscaler/cluster-autoscaler/utils/test"
 )
 
 func TestIsAwsNodeInfoSimilar(t *testing.T) {
-	comparator := CreateAwsNodeInfoComparator([]string{})
+	comparator := CreateAwsNodeInfoComparator([]string{}, config.NodeGroupDifferenceRatios{})
 	node1 := BuildTestNode("node1", 1000, 2000)
 	node2 := BuildTestNode("node2", 1000, 2000)
 
@@ -176,6 +177,6 @@ func TestIsAwsNodeInfoSimilar(t *testing.T) {
 func TestFindSimilarNodeGroupsAwsBasic(t *testing.T) {
 	context := &context.AutoscalingContext{}
 	ni1, ni2, ni3 := buildBasicNodeGroups(context)
-	processor := &BalancingNodeGroupSetProcessor{Comparator: CreateAwsNodeInfoComparator([]string{})}
+	processor := &BalancingNodeGroupSetProcessor{Comparator: CreateAwsNodeInfoComparator([]string{}, config.NodeGroupDifferenceRatios{})}
 	basicSimilarNodeGroupsTest(t, context, processor, ni1, ni2, ni3)
 }

cluster-autoscaler/processors/nodegroupset/azure_nodegroups.go

@@ -17,6 +17,7 @@ limitations under the License.
 package nodegroupset
 
 import (
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	schedulerframework "k8s.io/kubernetes/pkg/scheduler/framework"
 )
 
@@ -44,7 +45,7 @@ func nodesFromSameAzureNodePoolLegacy(n1, n2 *schedulerframework.NodeInfo) bool
 // CreateAzureNodeInfoComparator returns a comparator that checks if two nodes should be considered
 // part of the same NodeGroupSet. This is true if they either belong to the same Azure agentpool
 // or match usual conditions checked by IsCloudProviderNodeInfoSimilar, even if they have different agentpool labels.
-func CreateAzureNodeInfoComparator(extraIgnoredLabels []string) NodeInfoComparator {
+func CreateAzureNodeInfoComparator(extraIgnoredLabels []string, ratioOpts config.NodeGroupDifferenceRatios) NodeInfoComparator {
 	azureIgnoredLabels := make(map[string]bool)
 	for k, v := range BasicIgnoredLabels {
 		azureIgnoredLabels[k] = v
@@ -60,6 +61,6 @@ func CreateAzureNodeInfoComparator(extraIgnoredLabels []string) NodeInfoComparat
 		if nodesFromSameAzureNodePool(n1, n2) {
 			return true
 		}
-		return IsCloudProviderNodeInfoSimilar(n1, n2, azureIgnoredLabels)
+		return IsCloudProviderNodeInfoSimilar(n1, n2, azureIgnoredLabels, ratioOpts)
 	}
 }

cluster-autoscaler/processors/nodegroupset/azure_nodegroups_test.go

@@ -21,6 +21,7 @@ import (
 
 	"k8s.io/autoscaler/cluster-autoscaler/cloudprovider"
 	testprovider "k8s.io/autoscaler/cluster-autoscaler/cloudprovider/test"
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	"k8s.io/autoscaler/cluster-autoscaler/context"
 	. "k8s.io/autoscaler/cluster-autoscaler/utils/test"
 	schedulerframework "k8s.io/kubernetes/pkg/scheduler/framework"
@@ -29,7 +30,7 @@ import (
 )
 
 func TestIsAzureNodeInfoSimilar(t *testing.T) {
-	comparator := CreateAzureNodeInfoComparator([]string{"example.com/ready"})
+	comparator := CreateAzureNodeInfoComparator([]string{"example.com/ready"}, config.NodeGroupDifferenceRatios{})
 	n1 := BuildTestNode("node1", 1000, 2000)
 	n1.ObjectMeta.Labels["test-label"] = "test-value"
 	n1.ObjectMeta.Labels["character"] = "thing"
@@ -75,12 +76,12 @@ func TestIsAzureNodeInfoSimilar(t *testing.T) {
 func TestFindSimilarNodeGroupsAzureBasic(t *testing.T) {
 	context := &context.AutoscalingContext{}
 	ni1, ni2, ni3 := buildBasicNodeGroups(context)
-	processor := &BalancingNodeGroupSetProcessor{Comparator: CreateAzureNodeInfoComparator([]string{})}
+	processor := &BalancingNodeGroupSetProcessor{Comparator: CreateAzureNodeInfoComparator([]string{}, config.NodeGroupDifferenceRatios{})}
 	basicSimilarNodeGroupsTest(t, context, processor, ni1, ni2, ni3)
 }
 
 func TestFindSimilarNodeGroupsAzureByLabel(t *testing.T) {
-	processor := &BalancingNodeGroupSetProcessor{Comparator: CreateAzureNodeInfoComparator([]string{})}
+	processor := &BalancingNodeGroupSetProcessor{Comparator: CreateAzureNodeInfoComparator([]string{}, config.NodeGroupDifferenceRatios{})}
 	context := &context.AutoscalingContext{}
 
 	n1 := BuildTestNode("n1", 1000, 1000)

cluster-autoscaler/processors/nodegroupset/balancing_processor_test.go

@@ -23,6 +23,7 @@ import (
 
 	"k8s.io/autoscaler/cluster-autoscaler/cloudprovider"
 	testprovider "k8s.io/autoscaler/cluster-autoscaler/cloudprovider/test"
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	"k8s.io/autoscaler/cluster-autoscaler/context"
 	. "k8s.io/autoscaler/cluster-autoscaler/utils/test"
 
@@ -84,7 +85,7 @@ func basicSimilarNodeGroupsTest(
 func TestFindSimilarNodeGroups(t *testing.T) {
 	context := &context.AutoscalingContext{}
 	ni1, ni2, ni3 := buildBasicNodeGroups(context)
-	processor := NewDefaultNodeGroupSetProcessor([]string{})
+	processor := NewDefaultNodeGroupSetProcessor([]string{}, config.NodeGroupDifferenceRatios{})
 	basicSimilarNodeGroupsTest(t, context, processor, ni1, ni2, ni3)
 }
 
@@ -94,7 +95,7 @@ func TestFindSimilarNodeGroupsCustomLabels(t *testing.T) {
 	ni1.Node().Labels["example.com/ready"] = "true"
 	ni2.Node().Labels["example.com/ready"] = "false"
 
-	processor := NewDefaultNodeGroupSetProcessor([]string{"example.com/ready"})
+	processor := NewDefaultNodeGroupSetProcessor([]string{"example.com/ready"}, config.NodeGroupDifferenceRatios{})
 	basicSimilarNodeGroupsTest(t, context, processor, ni1, ni2, ni3)
 }
 
@@ -112,7 +113,7 @@ func TestFindSimilarNodeGroupsCustomComparator(t *testing.T) {
 }
 
 func TestBalanceSingleGroup(t *testing.T) {
-	processor := NewDefaultNodeGroupSetProcessor([]string{})
+	processor := NewDefaultNodeGroupSetProcessor([]string{}, config.NodeGroupDifferenceRatios{})
 	context := &context.AutoscalingContext{}
 
 	provider := testprovider.NewTestCloudProvider(nil, nil)
@@ -132,7 +133,7 @@ func TestBalanceSingleGroup(t *testing.T) {
 }
 
 func TestBalanceUnderMaxSize(t *testing.T) {
-	processor := NewDefaultNodeGroupSetProcessor([]string{})
+	processor := NewDefaultNodeGroupSetProcessor([]string{}, config.NodeGroupDifferenceRatios{})
 	context := &context.AutoscalingContext{}
 
 	provider := testprovider.NewTestCloudProvider(nil, nil)
@@ -182,7 +183,7 @@ func TestBalanceUnderMaxSize(t *testing.T) {
 }
 
 func TestBalanceHittingMaxSize(t *testing.T) {
-	processor := NewDefaultNodeGroupSetProcessor([]string{})
+	processor := NewDefaultNodeGroupSetProcessor([]string{}, config.NodeGroupDifferenceRatios{})
 	context := &context.AutoscalingContext{}
 
 	provider := testprovider.NewTestCloudProvider(nil, nil)

cluster-autoscaler/processors/nodegroupset/clusterapi_nodegroups.go

@@ -17,13 +17,14 @@ limitations under the License.
 package nodegroupset
 
 import (
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	schedulerframework "k8s.io/kubernetes/pkg/scheduler/framework"
 )
 
 // CreateClusterAPINodeInfoComparator returns a comparator that checks if two nodes should be considered
 // part of the same NodeGroupSet. This is true if they match usual conditions checked by IsCloudProviderNodeInfoSimilar,
 // even if they have different infrastructure provider-specific labels.
-func CreateClusterAPINodeInfoComparator(extraIgnoredLabels []string) NodeInfoComparator {
+func CreateClusterAPINodeInfoComparator(extraIgnoredLabels []string, ratioOpts config.NodeGroupDifferenceRatios) NodeInfoComparator {
 	capiIgnoredLabels := map[string]bool{
 		"topology.ebs.csi.aws.com/zone":                 true, // this is a label used by the AWS EBS CSI driver as a target for Persistent Volume Node Affinity
 		"topology.diskplugin.csi.alibabacloud.com/zone": true, // this is a label used by the Alibaba Cloud CSI driver as a target for Persistent Volume Node Affinity
@@ -41,6 +42,6 @@ func CreateClusterAPINodeInfoComparator(extraIgnoredLabels []string) NodeInfoCom
 	}
 
 	return func(n1, n2 *schedulerframework.NodeInfo) bool {
-		return IsCloudProviderNodeInfoSimilar(n1, n2, capiIgnoredLabels)
+		return IsCloudProviderNodeInfoSimilar(n1, n2, capiIgnoredLabels, ratioOpts)
 	}
 }

cluster-autoscaler/processors/nodegroupset/clusterapi_nodegroups_test.go

@@ -19,12 +19,13 @@ package nodegroupset
 import (
 	"testing"
 
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	"k8s.io/autoscaler/cluster-autoscaler/context"
 	. "k8s.io/autoscaler/cluster-autoscaler/utils/test"
 )
 
 func TestIsClusterAPINodeInfoSimilar(t *testing.T) {
-	comparator := CreateClusterAPINodeInfoComparator([]string{})
+	comparator := CreateClusterAPINodeInfoComparator([]string{}, config.NodeGroupDifferenceRatios{})
 	node1 := BuildTestNode("node1", 1000, 2000)
 	node2 := BuildTestNode("node2", 1000, 2000)
 
@@ -92,6 +93,6 @@ func TestIsClusterAPINodeInfoSimilar(t *testing.T) {
 func TestFindSimilarNodeGroupsClusterAPIBasic(t *testing.T) {
 	context := &context.AutoscalingContext{}
 	ni1, ni2, ni3 := buildBasicNodeGroups(context)
-	processor := &BalancingNodeGroupSetProcessor{Comparator: CreateClusterAPINodeInfoComparator([]string{})}
+	processor := &BalancingNodeGroupSetProcessor{Comparator: CreateClusterAPINodeInfoComparator([]string{}, config.NodeGroupDifferenceRatios{})}
 	basicSimilarNodeGroupsTest(t, context, processor, ni1, ni2, ni3)
 }

cluster-autoscaler/processors/nodegroupset/compare_nodegroups.go

@@ -21,22 +21,11 @@ import (
 
 	apiv1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	"k8s.io/autoscaler/cluster-autoscaler/utils/scheduler"
 	schedulerframework "k8s.io/kubernetes/pkg/scheduler/framework"
 )
 
-const (
-	// MaxAllocatableDifferenceRatio describes how Node.Status.Allocatable can differ between
-	// groups in the same NodeGroupSet
-	MaxAllocatableDifferenceRatio = 0.05
-	// MaxFreeDifferenceRatio describes how free resources (allocatable - daemon and system pods)
-	// can differ between groups in the same NodeGroupSet
-	MaxFreeDifferenceRatio = 0.05
-	// MaxCapacityMemoryDifferenceRatio describes how Node.Status.Capacity.Memory can differ between
-	// groups in the same NodeGroupSet
-	MaxCapacityMemoryDifferenceRatio = 0.015
-)
-
 // BasicIgnoredLabels define a set of basic labels that should be ignored when comparing the similarity
 // of two nodes. Customized IgnoredLabels can be implemented in the corresponding codes of
 // specific cloud provider and the BasicIgnoredLabels should always be considered part of them.
@@ -92,7 +81,7 @@ func compareLabels(nodes []*schedulerframework.NodeInfo, ignoredLabels map[strin
 }
 
 // CreateGenericNodeInfoComparator returns a generic comparator that checks for node group similarity
-func CreateGenericNodeInfoComparator(extraIgnoredLabels []string) NodeInfoComparator {
+func CreateGenericNodeInfoComparator(extraIgnoredLabels []string, ratioOpts config.NodeGroupDifferenceRatios) NodeInfoComparator {
 	genericIgnoredLabels := make(map[string]bool)
 	for k, v := range BasicIgnoredLabels {
 		genericIgnoredLabels[k] = v
@@ -102,7 +91,7 @@ func CreateGenericNodeInfoComparator(extraIgnoredLabels []string) NodeInfoCompar
 	}
 
 	return func(n1, n2 *schedulerframework.NodeInfo) bool {
-		return IsCloudProviderNodeInfoSimilar(n1, n2, genericIgnoredLabels)
+		return IsCloudProviderNodeInfoSimilar(n1, n2, genericIgnoredLabels, ratioOpts)
 	}
 }
 
@@ -111,7 +100,8 @@ func CreateGenericNodeInfoComparator(extraIgnoredLabels []string) NodeInfoCompar
 // somewhat arbitrary, but generally we check if resources provided by both nodes
 // are similar enough to likely be the same type of machine and if the set of labels
 // is the same (except for a set of labels passed in to be ignored like hostname or zone).
-func IsCloudProviderNodeInfoSimilar(n1, n2 *schedulerframework.NodeInfo, ignoredLabels map[string]bool) bool {
+func IsCloudProviderNodeInfoSimilar(
+	n1, n2 *schedulerframework.NodeInfo, ignoredLabels map[string]bool, ratioOpts config.NodeGroupDifferenceRatios) bool {
 	capacity := make(map[apiv1.ResourceName][]resource.Quantity)
 	allocatable := make(map[apiv1.ResourceName][]resource.Quantity)
 	free := make(map[apiv1.ResourceName][]resource.Quantity)
@@ -136,7 +126,7 @@ func IsCloudProviderNodeInfoSimilar(n1, n2 *schedulerframework.NodeInfo, ignored
 		}
 		switch kind {
 		case apiv1.ResourceMemory:
-			if !resourceListWithinTolerance(qtyList, MaxCapacityMemoryDifferenceRatio) {
+			if !resourceListWithinTolerance(qtyList, ratioOpts.MaxCapacityMemoryDifferenceRatio) {
 				return false
 			}
 		default:
@@ -150,10 +140,10 @@ func IsCloudProviderNodeInfoSimilar(n1, n2 *schedulerframework.NodeInfo, ignored
 	}
 
 	// For allocatable and free we allow resource quantities to be within a few % of each other
-	if !resourceMapsWithinTolerance(allocatable, MaxAllocatableDifferenceRatio) {
+	if !resourceMapsWithinTolerance(allocatable, ratioOpts.MaxAllocatableDifferenceRatio) {
 		return false
 	}
-	if !resourceMapsWithinTolerance(free, MaxFreeDifferenceRatio) {
+	if !resourceMapsWithinTolerance(free, ratioOpts.MaxFreeDifferenceRatio) {
 		return false
 	}
 

cluster-autoscaler/processors/nodegroupset/compare_nodegroups_test.go

@@ -21,6 +21,7 @@ import (
 
 	apiv1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	"k8s.io/autoscaler/cluster-autoscaler/utils/gpu"
 	. "k8s.io/autoscaler/cluster-autoscaler/utils/test"
 	schedulerframework "k8s.io/kubernetes/pkg/scheduler/framework"
@@ -41,14 +42,14 @@ func checkNodesSimilarWithPods(t *testing.T, n1, n2 *apiv1.Node, pods1, pods2 []
 }
 
 func TestIdenticalNodesSimilar(t *testing.T) {
-	comparator := CreateGenericNodeInfoComparator([]string{})
+	comparator := CreateGenericNodeInfoComparator([]string{}, config.NewDefaultNodeGroupDifferenceRatios())
 	n1 := BuildTestNode("node1", 1000, 2000)
 	n2 := BuildTestNode("node2", 1000, 2000)
 	checkNodesSimilar(t, n1, n2, comparator, true)
 }
 
 func TestNodesSimilarVariousRequirements(t *testing.T) {
-	comparator := CreateGenericNodeInfoComparator([]string{})
+	comparator := CreateGenericNodeInfoComparator([]string{}, config.NewDefaultNodeGroupDifferenceRatios())
 	n1 := BuildTestNode("node1", 1000, 2000)
 
 	// Different CPU capacity
@@ -74,7 +75,7 @@ func TestNodesSimilarVariousRequirements(t *testing.T) {
 }
 
 func TestNodesSimilarVariousRequirementsAndPods(t *testing.T) {
-	comparator := CreateGenericNodeInfoComparator([]string{})
+	comparator := CreateGenericNodeInfoComparator([]string{}, config.NewDefaultNodeGroupDifferenceRatios())
 	n1 := BuildTestNode("node1", 1000, 2000)
 	p1 := BuildTestPod("pod1", 500, 1000)
 	p1.Spec.NodeName = "node1"
@@ -100,22 +101,22 @@ func TestNodesSimilarVariousRequirementsAndPods(t *testing.T) {
 }
 
 func TestNodesSimilarVariousMemoryRequirements(t *testing.T) {
-	comparator := CreateGenericNodeInfoComparator([]string{})
+	comparator := CreateGenericNodeInfoComparator([]string{}, config.NewDefaultNodeGroupDifferenceRatios())
 	n1 := BuildTestNode("node1", 1000, 1000)
 
 	// Different memory capacity within tolerance
 	n2 := BuildTestNode("node2", 1000, 1000)
-	n2.Status.Capacity[apiv1.ResourceMemory] = *resource.NewQuantity(1000-(1000*MaxCapacityMemoryDifferenceRatio)+1, resource.DecimalSI)
+	n2.Status.Capacity[apiv1.ResourceMemory] = *resource.NewQuantity(1000-(1000*config.DefaultMaxCapacityMemoryDifferenceRatio)+1, resource.DecimalSI)
 	checkNodesSimilar(t, n1, n2, comparator, true)
 
 	// Different memory capacity exceeds tolerance
 	n3 := BuildTestNode("node3", 1000, 1000)
-	n3.Status.Capacity[apiv1.ResourceMemory] = *resource.NewQuantity(1000-(1000*MaxCapacityMemoryDifferenceRatio)-1, resource.DecimalSI)
+	n3.Status.Capacity[apiv1.ResourceMemory] = *resource.NewQuantity(1000-(1000*config.DefaultMaxCapacityMemoryDifferenceRatio)-1, resource.DecimalSI)
 	checkNodesSimilar(t, n1, n3, comparator, false)
 }
 
 func TestNodesSimilarVariousLargeMemoryRequirementsM5XLarge(t *testing.T) {
-	comparator := CreateGenericNodeInfoComparator([]string{})
+	comparator := CreateGenericNodeInfoComparator([]string{}, config.NewDefaultNodeGroupDifferenceRatios())
 
 	// Use realistic memory capacity (taken from real nodes)
 	// 15944120 KB ~= 16GiB (m5.xLarge)
@@ -137,7 +138,7 @@ func TestNodesSimilarVariousLargeMemoryRequirementsM5XLarge(t *testing.T) {
 }
 
 func TestNodesSimilarVariousLargeMemoryRequirementsM516XLarge(t *testing.T) {
-	comparator := CreateGenericNodeInfoComparator([]string{})
+	comparator := CreateGenericNodeInfoComparator([]string{}, config.NewDefaultNodeGroupDifferenceRatios())
 
 	// Use realistic memory capacity (taken from real nodes)
 	// 257217528 KB ~= 256GiB (m5.16xLarge)
@@ -159,7 +160,7 @@ func TestNodesSimilarVariousLargeMemoryRequirementsM516XLarge(t *testing.T) {
 }
 
 func TestNodesSimilarVariousLabels(t *testing.T) {
-	comparator := CreateGenericNodeInfoComparator([]string{"example.com/ready"})
+	comparator := CreateGenericNodeInfoComparator([]string{"example.com/ready"}, config.NewDefaultNodeGroupDifferenceRatios())
 	n1 := BuildTestNode("node1", 1000, 2000)
 	n1.ObjectMeta.Labels["test-label"] = "test-value"
 	n1.ObjectMeta.Labels["character"] = "winnie the pooh"

cluster-autoscaler/processors/nodegroupset/gce_nodegroups.go

@@ -17,13 +17,14 @@ limitations under the License.
 package nodegroupset
 
 import (
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	schedulerframework "k8s.io/kubernetes/pkg/scheduler/framework"
 )
 
 // CreateGceNodeInfoComparator returns a comparator that checks if two nodes should be considered
 // part of the same NodeGroupSet. This is true if they match usual conditions checked by IsCloudProviderNodeInfoSimilar,
 // even if they have different GCE-specific labels.
-func CreateGceNodeInfoComparator(extraIgnoredLabels []string) NodeInfoComparator {
+func CreateGceNodeInfoComparator(extraIgnoredLabels []string, ratioOpts config.NodeGroupDifferenceRatios) NodeInfoComparator {
 	gceIgnoredLabels := map[string]bool{
 		"topology.gke.io/zone": true,
 	}
@@ -37,6 +38,6 @@ func CreateGceNodeInfoComparator(extraIgnoredLabels []string) NodeInfoComparator
 	}
 
 	return func(n1, n2 *schedulerframework.NodeInfo) bool {
-		return IsCloudProviderNodeInfoSimilar(n1, n2, gceIgnoredLabels)
+		return IsCloudProviderNodeInfoSimilar(n1, n2, gceIgnoredLabels, ratioOpts)
 	}
 }

cluster-autoscaler/processors/nodegroupset/nodegroup_set_processor.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 
 	"k8s.io/autoscaler/cluster-autoscaler/cloudprovider"
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	"k8s.io/autoscaler/cluster-autoscaler/context"
 	"k8s.io/autoscaler/cluster-autoscaler/utils/errors"
 	schedulerframework "k8s.io/kubernetes/pkg/scheduler/framework"
@@ -70,8 +71,8 @@ func (n *NoOpNodeGroupSetProcessor) BalanceScaleUpBetweenGroups(context *context
 func (n *NoOpNodeGroupSetProcessor) CleanUp() {}
 
 // NewDefaultNodeGroupSetProcessor creates an instance of NodeGroupSetProcessor.
-func NewDefaultNodeGroupSetProcessor(ignoredLabels []string) NodeGroupSetProcessor {
+func NewDefaultNodeGroupSetProcessor(ignoredLabels []string, ratioOpts config.NodeGroupDifferenceRatios) NodeGroupSetProcessor {
 	return &BalancingNodeGroupSetProcessor{
-		Comparator: CreateGenericNodeInfoComparator(ignoredLabels),
+		Comparator: CreateGenericNodeInfoComparator(ignoredLabels, ratioOpts),
 	}
 }

cluster-autoscaler/processors/processors.go

@@ -17,6 +17,7 @@ limitations under the License.
 package processors
 
 import (
+	"k8s.io/autoscaler/cluster-autoscaler/config"
 	"k8s.io/autoscaler/cluster-autoscaler/processors/actionablecluster"
 	"k8s.io/autoscaler/cluster-autoscaler/processors/customresources"
 	"k8s.io/autoscaler/cluster-autoscaler/processors/nodegroupconfig"
@@ -67,7 +68,11 @@ func DefaultProcessors() *AutoscalingProcessors {
 	return &AutoscalingProcessors{
 		PodListProcessor:       pods.NewDefaultPodListProcessor(),
 		NodeGroupListProcessor: nodegroups.NewDefaultNodeGroupListProcessor(),
-		NodeGroupSetProcessor:      nodegroupset.NewDefaultNodeGroupSetProcessor([]string{}),
+		NodeGroupSetProcessor: nodegroupset.NewDefaultNodeGroupSetProcessor([]string{}, config.NodeGroupDifferenceRatios{
+			MaxAllocatableDifferenceRatio:    config.DefaultMaxAllocatableDifferenceRatio,
+			MaxCapacityMemoryDifferenceRatio: config.DefaultMaxCapacityMemoryDifferenceRatio,
+			MaxFreeDifferenceRatio:           config.DefaultMaxFreeDifferenceRatio,
+		}),
 		ScaleUpStatusProcessor:     status.NewDefaultScaleUpStatusProcessor(),
 		ScaleDownNodeProcessor:     nodes.NewPreFilteringScaleDownNodeProcessor(),
 		ScaleDownSetProcessor:      nodes.NewPostFilteringScaleDownNodeProcessor(),