feat: refactoring thresholds and usage assessment

this commit refactors the thresholds and usage assessment for the node
utilization plugins. both high and low plugins are affected by this
change.

Author: ricardomaraschini

go.mod

@@ -30,6 +30,8 @@ require (
 	sigs.k8s.io/yaml v1.4.0
 )
 
+require golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56
+
 require (
 	cel.dev/expr v0.18.0 // indirect
 	github.com/BurntSushi/toml v0.3.1 // indirect
@@ -96,7 +98,6 @@ require (
 	go.uber.org/multierr v1.11.0 // indirect
 	go.uber.org/zap v1.27.0 // indirect
 	golang.org/x/crypto v0.31.0 // indirect
-	golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56 // indirect
 	golang.org/x/mod v0.21.0 // indirect
 	golang.org/x/net v0.30.0 // indirect
 	golang.org/x/oauth2 v0.23.0 // indirect

pkg/framework/plugins/nodeutilization/highnodeutilization.go

@@ -28,6 +28,7 @@ import (
 	nodeutil "sigs.k8s.io/descheduler/pkg/descheduler/node"
 
 	podutil "sigs.k8s.io/descheduler/pkg/descheduler/pod"
+	"sigs.k8s.io/descheduler/pkg/framework/plugins/nodeutilization/normalizer"
 	frameworktypes "sigs.k8s.io/descheduler/pkg/framework/types"
 )
 
@@ -102,11 +103,17 @@ func (h *HighNodeUtilization) Balance(ctx context.Context, nodes []*v1.Node) *fr
 	}
 
 	nodesMap, nodesUsageMap, podListMap := getNodeUsageSnapshot(nodes, h.usageClient)
-	nodeThresholdsMap := getStaticNodeThresholds(nodes, h.args.Thresholds, h.targetThresholds)
-	nodesUsageAsNodeThresholdsMap := nodeUsageToResourceThresholds(nodesUsageMap, nodesMap)
+
+	usage, thresholds := assessNodesUsagesAndStaticThresholds(
+		nodesUsageMap,
+		referencedResourceListForNodesCapacity(nodes),
+		h.args.Thresholds,
+		h.targetThresholds,
+	)
+
 	nodeGroups := classifyNodeUsage(
-		nodesUsageAsNodeThresholdsMap,
-		nodeThresholdsMap,
+		usage,
+		thresholds,
 		[]classifierFnc{
 			// underutilized nodes
 			func(nodeName string, usage, threshold api.ResourceThresholds) bool {
@@ -128,16 +135,21 @@ func (h *HighNodeUtilization) Balance(ctx context.Context, nodes []*v1.Node) *fr
 	category := []string{"underutilized", "overutilized"}
 	for i := range nodeGroups {
 		for nodeName := range nodeGroups[i] {
-			klog.InfoS("Node is "+category[i], "node", klog.KObj(nodesMap[nodeName]), "usage", nodesUsageMap[nodeName], "usagePercentage", resourceUsagePercentages(nodesUsageMap[nodeName], nodesMap[nodeName], true))
+			klog.InfoS(
+				fmt.Sprintf("Node is %s", category[i]),
+				"node", klog.KObj(nodesMap[nodeName]),
+				"usage", nodesUsageMap[nodeName],
+				"usagePercentage", normalizer.Round(usage[nodeName]),
+			)
 			nodeInfos[i] = append(nodeInfos[i], NodeInfo{
 				NodeUsage: NodeUsage{
 					node:    nodesMap[nodeName],
 					usage:   nodesUsageMap[nodeName], // get back the original node usage
 					allPods: podListMap[nodeName],
 				},
 				thresholds: NodeThresholds{
-					lowResourceThreshold:  resourceThresholdsToNodeUsage(nodeThresholdsMap[nodeName][0], nodesMap[nodeName]),
-					highResourceThreshold: resourceThresholdsToNodeUsage(nodeThresholdsMap[nodeName][1], nodesMap[nodeName]),
+					lowResourceThreshold:  resourceThresholdsToNodeUsage(thresholds[nodeName][0], nodesMap[nodeName]),
+					highResourceThreshold: resourceThresholdsToNodeUsage(thresholds[nodeName][1], nodesMap[nodeName]),
 				},
 			})
 		}

pkg/framework/plugins/nodeutilization/lownodeutilization.go

@@ -28,6 +28,7 @@ import (
 	"sigs.k8s.io/descheduler/pkg/descheduler/evictions"
 	nodeutil "sigs.k8s.io/descheduler/pkg/descheduler/node"
 	podutil "sigs.k8s.io/descheduler/pkg/descheduler/pod"
+	"sigs.k8s.io/descheduler/pkg/framework/plugins/nodeutilization/normalizer"
 	frameworktypes "sigs.k8s.io/descheduler/pkg/framework/types"
 )
 
@@ -123,17 +124,28 @@ func (l *LowNodeUtilization) Balance(ctx context.Context, nodes []*v1.Node) *fra
 	}
 
 	nodesMap, nodesUsageMap, podListMap := getNodeUsageSnapshot(nodes, l.usageClient)
-	var nodeThresholdsMap map[string][]api.ResourceThresholds
+
+	var usage map[string]api.ResourceThresholds
+	var thresholds map[string][]api.ResourceThresholds
 	if l.args.UseDeviationThresholds {
-		nodeThresholdsMap = getNodeThresholdsFromAverageNodeUsage(nodes, l.usageClient, l.args.Thresholds, l.args.TargetThresholds)
+		usage, thresholds = assessNodesUsagesAndRelativeThresholds(
+			nodesUsageMap,
+			referencedResourceListForNodesCapacity(nodes),
+			l.args.Thresholds,
+			l.args.TargetThresholds,
+		)
 	} else {
-		nodeThresholdsMap = getStaticNodeThresholds(nodes, l.args.Thresholds, l.args.TargetThresholds)
+		usage, thresholds = assessNodesUsagesAndStaticThresholds(
+			nodesUsageMap,
+			referencedResourceListForNodesCapacity(nodes),
+			l.args.Thresholds,
+			l.args.TargetThresholds,
+		)
 	}
-	nodesUsageAsNodeThresholdsMap := nodeUsageToResourceThresholds(nodesUsageMap, nodesMap)
 
 	nodeGroups := classifyNodeUsage(
-		nodesUsageAsNodeThresholdsMap,
-		nodeThresholdsMap,
+		usage,
+		thresholds,
 		[]classifierFnc{
 			// underutilization
 			func(nodeName string, usage, threshold api.ResourceThresholds) bool {
@@ -156,7 +168,12 @@ func (l *LowNodeUtilization) Balance(ctx context.Context, nodes []*v1.Node) *fra
 	listedNodes := map[string]struct{}{}
 	for i := range nodeGroups {
 		for nodeName := range nodeGroups[i] {
-			klog.InfoS("Node is "+category[i], "node", klog.KObj(nodesMap[nodeName]), "usage", nodesUsageMap[nodeName], "usagePercentage", resourceUsagePercentages(nodesUsageMap[nodeName], nodesMap[nodeName], true))
+			klog.InfoS(
+				fmt.Sprintf("Node is %x", category[i]),
+				"node", klog.KObj(nodesMap[nodeName]),
+				"usage", nodesUsageMap[nodeName],
+				"usagePercentage", normalizer.Round(usage[nodeName]),
+			)
 			listedNodes[nodeName] = struct{}{}
 			nodeInfos[i] = append(nodeInfos[i], NodeInfo{
 				NodeUsage: NodeUsage{
@@ -165,15 +182,20 @@ func (l *LowNodeUtilization) Balance(ctx context.Context, nodes []*v1.Node) *fra
 					allPods: podListMap[nodeName],
 				},
 				thresholds: NodeThresholds{
-					lowResourceThreshold:  resourceThresholdsToNodeUsage(nodeThresholdsMap[nodeName][0], nodesMap[nodeName]),
-					highResourceThreshold: resourceThresholdsToNodeUsage(nodeThresholdsMap[nodeName][1], nodesMap[nodeName]),
+					lowResourceThreshold:  resourceThresholdsToNodeUsage(thresholds[nodeName][0], nodesMap[nodeName]),
+					highResourceThreshold: resourceThresholdsToNodeUsage(thresholds[nodeName][1], nodesMap[nodeName]),
 				},
 			})
 		}
 	}
 	for nodeName := range nodesMap {
 		if _, ok := listedNodes[nodeName]; !ok {
-			klog.InfoS("Node is appropriately utilized", "node", klog.KObj(nodesMap[nodeName]), "usage", nodesUsageMap[nodeName], "usagePercentage", resourceUsagePercentages(nodesUsageMap[nodeName], nodesMap[nodeName], true))
+			klog.InfoS(
+				"Node is appropriately utilized",
+				"node", klog.KObj(nodesMap[nodeName]),
+				"usage", nodesUsageMap[nodeName],
+				"usagePercentage", normalizer.Round(usage[nodeName]),
+			)
 		}
 	}