Merge pull request #322 from lixiang233/move_pod_sort

Move sortPodsBasedOnPriority to pod util
2026-01-26 05:14:13 +01:00 · 2020-06-22 12:21:40 -07:00
parent e374229707 65a03e76bf
commit c713537d56
8 changed files with 237 additions and 181 deletions
--- a/README.md
+++ b/README.md
@@ -238,7 +238,8 @@ When the descheduler decides to evict pods from a node, it employs the following
 never evicted because these pods won't be recreated.
 * Pods associated with DaemonSets are never evicted.
 * Pods with local storage are never evicted.
-* Best efforts pods are evicted before burstable and guaranteed pods.
+* In `LowNodeUtilization` and `RemovePodsViolatingInterPodAntiAffinity`, pods are evicted by their priority from low to high, and if they have same priority,
+best effort pods are evicted before burstable and guaranteed pods.
 * All types of pods with the annotation descheduler.alpha.kubernetes.io/evict are evicted. This
  annotation is used to override checks which prevent eviction and users can select which pod is evicted.
  Users should know how and if the pod will be recreated.
--- a/pkg/descheduler/pod/pods.go
+++ b/pkg/descheduler/pod/pods.go
@@ -23,6 +23,7 @@ import (
 	"k8s.io/apimachinery/pkg/fields"
 	clientset "k8s.io/client-go/kubernetes"
 	"sigs.k8s.io/descheduler/pkg/utils"
+	"sort"
 )

 // ListPodsOnANode lists all of the pods on a node
@@ -68,3 +69,27 @@ func IsBurstablePod(pod *v1.Pod) bool {
 func IsGuaranteedPod(pod *v1.Pod) bool {
 	return utils.GetPodQOS(pod) == v1.PodQOSGuaranteed
 }
+
+// SortPodsBasedOnPriorityLowToHigh sorts pods based on their priorities from low to high.
+// If pods have same priorities, they will be sorted by QoS in the following order:
+// BestEffort, Burstable, Guaranteed
+func SortPodsBasedOnPriorityLowToHigh(pods []*v1.Pod) {
+	sort.Slice(pods, func(i, j int) bool {
+		if pods[i].Spec.Priority == nil && pods[j].Spec.Priority != nil {
+			return true
+		}
+		if pods[j].Spec.Priority == nil && pods[i].Spec.Priority != nil {
+			return false
+		}
+		if (pods[j].Spec.Priority == nil && pods[i].Spec.Priority == nil) || (*pods[i].Spec.Priority == *pods[j].Spec.Priority) {
+			if IsBestEffortPod(pods[i]) {
+				return true
+			}
+			if IsBurstablePod(pods[i]) && IsGuaranteedPod(pods[j]) {
+				return true
+			}
+			return false
+		}
+		return *pods[i].Spec.Priority < *pods[j].Spec.Priority
+	})
+}
--- a/pkg/descheduler/pod/pods_test.go
+++ b/pkg/descheduler/pod/pods_test.go
@@ -19,6 +19,7 @@ package pod
 import (
 	"context"
 	"fmt"
+	"reflect"
 	"strings"
 	"testing"

@@ -29,6 +30,11 @@ import (
 	"sigs.k8s.io/descheduler/test"
 )

+var (
+	lowPriority  = int32(0)
+	highPriority = int32(10000)
+)
+
 func TestListPodsOnANode(t *testing.T) {
 	testCases := []struct {
 		name             string
@@ -67,3 +73,43 @@ func TestListPodsOnANode(t *testing.T) {
 		}
 	}
 }
+
+func TestSortPodsBasedOnPriorityLowToHigh(t *testing.T) {
+	n1 := test.BuildTestNode("n1", 4000, 3000, 9, nil)
+
+	p1 := test.BuildTestPod("p1", 400, 0, n1.Name, func(pod *v1.Pod) {
+		test.SetPodPriority(pod, lowPriority)
+	})
+
+	// BestEffort
+	p2 := test.BuildTestPod("p2", 400, 0, n1.Name, func(pod *v1.Pod) {
+		test.SetPodPriority(pod, highPriority)
+		test.MakeBestEffortPod(pod)
+	})
+
+	// Burstable
+	p3 := test.BuildTestPod("p3", 400, 0, n1.Name, func(pod *v1.Pod) {
+		test.SetPodPriority(pod, highPriority)
+		test.MakeBurstablePod(pod)
+	})
+
+	// Guaranteed
+	p4 := test.BuildTestPod("p4", 400, 100, n1.Name, func(pod *v1.Pod) {
+		test.SetPodPriority(pod, highPriority)
+		test.MakeGuaranteedPod(pod)
+	})
+
+	// Best effort with nil priorities.
+	p5 := test.BuildTestPod("p5", 400, 100, n1.Name, test.MakeBestEffortPod)
+	p5.Spec.Priority = nil
+
+	p6 := test.BuildTestPod("p6", 400, 100, n1.Name, test.MakeGuaranteedPod)
+	p6.Spec.Priority = nil
+
+	podList := []*v1.Pod{p4, p3, p2, p1, p6, p5}
+
+	SortPodsBasedOnPriorityLowToHigh(podList)
+	if !reflect.DeepEqual(podList[len(podList)-1], p4) {
+		t.Errorf("Expected last pod in sorted list to be %v which of highest priority and guaranteed but got %v", p4, podList[len(podList)-1])
+	}
+}
--- a/pkg/descheduler/strategies/lownodeutilization.go
+++ b/pkg/descheduler/strategies/lownodeutilization.go
@@ -247,7 +247,7 @@ func evictPodsFromTargetNodes(
 			evictablePods = append(append(burstablePods, bestEffortPods...), guaranteedPods...)

 			// sort the evictable Pods based on priority. This also sorts them based on QoS. If there are multiple pods with same priority, they are sorted based on QoS tiers.
-			sortPodsBasedOnPriority(evictablePods)
+			podutil.SortPodsBasedOnPriorityLowToHigh(evictablePods)
 			evictPods(ctx, evictablePods, targetThresholds, nodeCapacity, node.usage, &totalPods, &totalCPU, &totalMem, taintsOfLowNodes, podEvictor, node.node)
 		} else {
 			// TODO: Remove this when we support only priority.
@@ -338,28 +338,6 @@ func sortNodesByUsage(nodes []NodeUsageMap) {
 	})
 }

-// sortPodsBasedOnPriority sorts pods based on priority and if their priorities are equal, they are sorted based on QoS tiers.
-func sortPodsBasedOnPriority(evictablePods []*v1.Pod) {
-	sort.Slice(evictablePods, func(i, j int) bool {
-		if evictablePods[i].Spec.Priority == nil && evictablePods[j].Spec.Priority != nil {
-			return true
-		}
-		if evictablePods[j].Spec.Priority == nil && evictablePods[i].Spec.Priority != nil {
-			return false
-		}
-		if (evictablePods[j].Spec.Priority == nil && evictablePods[i].Spec.Priority == nil) || (*evictablePods[i].Spec.Priority == *evictablePods[j].Spec.Priority) {
-			if podutil.IsBestEffortPod(evictablePods[i]) {
-				return true
-			}
-			if podutil.IsBurstablePod(evictablePods[i]) && podutil.IsGuaranteedPod(evictablePods[j]) {
-				return true
-			}
-			return false
-		}
-		return *evictablePods[i].Spec.Priority < *evictablePods[j].Spec.Priority
-	})
-}
-
 // createNodePodsMap returns nodepodsmap with evictable pods on node.
 func createNodePodsMap(ctx context.Context, client clientset.Interface, nodes []*v1.Node) NodePodsMap {
 	npm := NodePodsMap{}
--- a/pkg/descheduler/strategies/lownodeutilization_test.go
+++ b/pkg/descheduler/strategies/lownodeutilization_test.go
@@ -22,15 +22,13 @@ import (
 	"strings"
 	"testing"

-	"reflect"
-
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/api/policy/v1beta1"
 	"k8s.io/apimachinery/pkg/api/resource"
 	"k8s.io/apimachinery/pkg/fields"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
-	serializer "k8s.io/apimachinery/pkg/runtime/serializer"
+	"k8s.io/apimachinery/pkg/runtime/serializer"
 	"k8s.io/apimachinery/pkg/watch"
 	"k8s.io/client-go/kubernetes/fake"
 	core "k8s.io/client-go/testing"
@@ -45,30 +43,6 @@ var (
 	highPriority = int32(10000)
 )

-func setRSOwnerRef(pod *v1.Pod)          { pod.ObjectMeta.OwnerReferences = test.GetReplicaSetOwnerRefList() }
-func setDSOwnerRef(pod *v1.Pod)          { pod.ObjectMeta.OwnerReferences = test.GetDaemonSetOwnerRefList() }
-func setNormalOwnerRef(pod *v1.Pod)      { pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList() }
-func setHighPriority(pod *v1.Pod)        { pod.Spec.Priority = &highPriority }
-func setLowPriority(pod *v1.Pod)         { pod.Spec.Priority = &lowPriority }
-func setNodeUnschedulable(node *v1.Node) { node.Spec.Unschedulable = true }
-
-func makeBestEffortPod(pod *v1.Pod) {
-	pod.Spec.Containers[0].Resources.Requests = nil
-	pod.Spec.Containers[0].Resources.Requests = nil
-	pod.Spec.Containers[0].Resources.Limits = nil
-	pod.Spec.Containers[0].Resources.Limits = nil
-}
-
-func makeBurstablePod(pod *v1.Pod) {
-	pod.Spec.Containers[0].Resources.Limits = nil
-	pod.Spec.Containers[0].Resources.Limits = nil
-}
-
-func makeGuaranteedPod(pod *v1.Pod) {
-	pod.Spec.Containers[0].Resources.Limits[v1.ResourceCPU] = pod.Spec.Containers[0].Resources.Requests[v1.ResourceCPU]
-	pod.Spec.Containers[0].Resources.Limits[v1.ResourceMemory] = pod.Spec.Containers[0].Resources.Requests[v1.ResourceMemory]
-}
-
 func TestLowNodeUtilization(t *testing.T) {
 	ctx := context.Background()
 	n1NodeName := "n1"
@@ -99,19 +73,19 @@ func TestLowNodeUtilization(t *testing.T) {
 			nodes: map[string]*v1.Node{
 				n1NodeName: test.BuildTestNode(n1NodeName, 4000, 3000, 9, nil),
 				n2NodeName: test.BuildTestNode(n2NodeName, 4000, 3000, 10, nil),
-				n3NodeName: test.BuildTestNode(n3NodeName, 4000, 3000, 10, setNodeUnschedulable),
+				n3NodeName: test.BuildTestNode(n3NodeName, 4000, 3000, 10, test.SetNodeUnschedulable),
 			},
 			pods: map[string]*v1.PodList{
 				n1NodeName: {
 					Items: []v1.Pod{
 						// These won't be evicted.
-						*test.BuildTestPod("p1", 400, 0, n1NodeName, setDSOwnerRef),
-						*test.BuildTestPod("p2", 400, 0, n1NodeName, setDSOwnerRef),
-						*test.BuildTestPod("p3", 400, 0, n1NodeName, setDSOwnerRef),
-						*test.BuildTestPod("p4", 400, 0, n1NodeName, setDSOwnerRef),
+						*test.BuildTestPod("p1", 400, 0, n1NodeName, test.SetDSOwnerRef),
+						*test.BuildTestPod("p2", 400, 0, n1NodeName, test.SetDSOwnerRef),
+						*test.BuildTestPod("p3", 400, 0, n1NodeName, test.SetDSOwnerRef),
+						*test.BuildTestPod("p4", 400, 0, n1NodeName, test.SetDSOwnerRef),
 						*test.BuildTestPod("p5", 400, 0, n1NodeName, func(pod *v1.Pod) {
 							// A pod with local storage.
-							setNormalOwnerRef(pod)
+							test.SetNormalOwnerRef(pod)
 							pod.Spec.Volumes = []v1.Volume{
 								{
 									Name: "sample",
@@ -135,7 +109,7 @@ func TestLowNodeUtilization(t *testing.T) {
 				},
 				n2NodeName: {
 					Items: []v1.Pod{
-						*test.BuildTestPod("p9", 400, 0, n1NodeName, setRSOwnerRef),
+						*test.BuildTestPod("p9", 400, 0, n1NodeName, test.SetRSOwnerRef),
 					},
 				},
 				n3NodeName: {},
@@ -155,21 +129,21 @@ func TestLowNodeUtilization(t *testing.T) {
 			nodes: map[string]*v1.Node{
 				n1NodeName: test.BuildTestNode(n1NodeName, 4000, 3000, 9, nil),
 				n2NodeName: test.BuildTestNode(n2NodeName, 4000, 3000, 10, nil),
-				n3NodeName: test.BuildTestNode(n3NodeName, 4000, 3000, 10, setNodeUnschedulable),
+				n3NodeName: test.BuildTestNode(n3NodeName, 4000, 3000, 10, test.SetNodeUnschedulable),
 			},
 			pods: map[string]*v1.PodList{
 				n1NodeName: {
 					Items: []v1.Pod{
-						*test.BuildTestPod("p1", 400, 0, n1NodeName, setRSOwnerRef),
-						*test.BuildTestPod("p2", 400, 0, n1NodeName, setRSOwnerRef),
-						*test.BuildTestPod("p3", 400, 0, n1NodeName, setRSOwnerRef),
-						*test.BuildTestPod("p4", 400, 0, n1NodeName, setRSOwnerRef),
-						*test.BuildTestPod("p5", 400, 0, n1NodeName, setRSOwnerRef),
+						*test.BuildTestPod("p1", 400, 0, n1NodeName, test.SetRSOwnerRef),
+						*test.BuildTestPod("p2", 400, 0, n1NodeName, test.SetRSOwnerRef),
+						*test.BuildTestPod("p3", 400, 0, n1NodeName, test.SetRSOwnerRef),
+						*test.BuildTestPod("p4", 400, 0, n1NodeName, test.SetRSOwnerRef),
+						*test.BuildTestPod("p5", 400, 0, n1NodeName, test.SetRSOwnerRef),
 						// These won't be evicted.
-						*test.BuildTestPod("p6", 400, 0, n1NodeName, setDSOwnerRef),
+						*test.BuildTestPod("p6", 400, 0, n1NodeName, test.SetDSOwnerRef),
 						*test.BuildTestPod("p7", 400, 0, n1NodeName, func(pod *v1.Pod) {
 							// A pod with local storage.
-							setNormalOwnerRef(pod)
+							test.SetNormalOwnerRef(pod)
 							pod.Spec.Volumes = []v1.Volume{
 								{
 									Name: "sample",
@@ -193,7 +167,7 @@ func TestLowNodeUtilization(t *testing.T) {
 				},
 				n2NodeName: {
 					Items: []v1.Pod{
-						*test.BuildTestPod("p9", 400, 0, n1NodeName, setRSOwnerRef),
+						*test.BuildTestPod("p9", 400, 0, n1NodeName, test.SetRSOwnerRef),
 					},
 				},
 				n3NodeName: {},
@@ -213,21 +187,21 @@ func TestLowNodeUtilization(t *testing.T) {
 			nodes: map[string]*v1.Node{
 				n1NodeName: test.BuildTestNode(n1NodeName, 4000, 3000, 9, nil),
 				n2NodeName: test.BuildTestNode(n2NodeName, 4000, 3000, 10, nil),
-				n3NodeName: test.BuildTestNode(n3NodeName, 4000, 3000, 10, setNodeUnschedulable),
+				n3NodeName: test.BuildTestNode(n3NodeName, 4000, 3000, 10, test.SetNodeUnschedulable),
 			},
 			pods: map[string]*v1.PodList{
 				n1NodeName: {
 					Items: []v1.Pod{
-						*test.BuildTestPod("p1", 400, 300, n1NodeName, setRSOwnerRef),
-						*test.BuildTestPod("p2", 400, 300, n1NodeName, setRSOwnerRef),
-						*test.BuildTestPod("p3", 400, 300, n1NodeName, setRSOwnerRef),
-						*test.BuildTestPod("p4", 400, 300, n1NodeName, setRSOwnerRef),
-						*test.BuildTestPod("p5", 400, 300, n1NodeName, setRSOwnerRef),
+						*test.BuildTestPod("p1", 400, 300, n1NodeName, test.SetRSOwnerRef),
+						*test.BuildTestPod("p2", 400, 300, n1NodeName, test.SetRSOwnerRef),
+						*test.BuildTestPod("p3", 400, 300, n1NodeName, test.SetRSOwnerRef),
+						*test.BuildTestPod("p4", 400, 300, n1NodeName, test.SetRSOwnerRef),
+						*test.BuildTestPod("p5", 400, 300, n1NodeName, test.SetRSOwnerRef),
 						// These won't be evicted.
-						*test.BuildTestPod("p6", 400, 300, n1NodeName, setDSOwnerRef),
+						*test.BuildTestPod("p6", 400, 300, n1NodeName, test.SetDSOwnerRef),
 						*test.BuildTestPod("p7", 400, 300, n1NodeName, func(pod *v1.Pod) {
 							// A pod with local storage.
-							setNormalOwnerRef(pod)
+							test.SetNormalOwnerRef(pod)
 							pod.Spec.Volumes = []v1.Volume{
 								{
 									Name: "sample",
@@ -251,7 +225,7 @@ func TestLowNodeUtilization(t *testing.T) {
 				},
 				n2NodeName: {
 					Items: []v1.Pod{
-						*test.BuildTestPod("p9", 400, 2100, n1NodeName, setRSOwnerRef),
+						*test.BuildTestPod("p9", 400, 2100, n1NodeName, test.SetRSOwnerRef),
 					},
 				},
 				n3NodeName: {},
@@ -272,40 +246,40 @@ func TestLowNodeUtilization(t *testing.T) {
 			nodes: map[string]*v1.Node{
 				n1NodeName: test.BuildTestNode(n1NodeName, 4000, 3000, 9, nil),
 				n2NodeName: test.BuildTestNode(n2NodeName, 4000, 3000, 10, nil),
-				n3NodeName: test.BuildTestNode(n3NodeName, 4000, 3000, 10, setNodeUnschedulable),
+				n3NodeName: test.BuildTestNode(n3NodeName, 4000, 3000, 10, test.SetNodeUnschedulable),
 			},
 			pods: map[string]*v1.PodList{
 				n1NodeName: {
 					Items: []v1.Pod{
 						*test.BuildTestPod("p1", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setRSOwnerRef(pod)
-							setHighPriority(pod)
+							test.SetRSOwnerRef(pod)
+							test.SetPodPriority(pod, highPriority)
 						}),
 						*test.BuildTestPod("p2", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setRSOwnerRef(pod)
-							setHighPriority(pod)
+							test.SetRSOwnerRef(pod)
+							test.SetPodPriority(pod, highPriority)
 						}),
 						*test.BuildTestPod("p3", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setRSOwnerRef(pod)
-							setHighPriority(pod)
+							test.SetRSOwnerRef(pod)
+							test.SetPodPriority(pod, highPriority)
 						}),
 						*test.BuildTestPod("p4", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setRSOwnerRef(pod)
-							setHighPriority(pod)
+							test.SetRSOwnerRef(pod)
+							test.SetPodPriority(pod, highPriority)
 						}),
 						*test.BuildTestPod("p5", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setRSOwnerRef(pod)
-							setLowPriority(pod)
+							test.SetRSOwnerRef(pod)
+							test.SetPodPriority(pod, lowPriority)
 						}),
 						// These won't be evicted.
 						*test.BuildTestPod("p6", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setDSOwnerRef(pod)
-							setHighPriority(pod)
+							test.SetDSOwnerRef(pod)
+							test.SetPodPriority(pod, highPriority)
 						}),
 						*test.BuildTestPod("p7", 400, 0, n1NodeName, func(pod *v1.Pod) {
 							// A pod with local storage.
-							setNormalOwnerRef(pod)
-							setLowPriority(pod)
+							test.SetNormalOwnerRef(pod)
+							test.SetPodPriority(pod, lowPriority)
 							pod.Spec.Volumes = []v1.Volume{
 								{
 									Name: "sample",
@@ -329,7 +303,7 @@ func TestLowNodeUtilization(t *testing.T) {
 				},
 				n2NodeName: {
 					Items: []v1.Pod{
-						*test.BuildTestPod("p9", 400, 0, n1NodeName, setRSOwnerRef),
+						*test.BuildTestPod("p9", 400, 0, n1NodeName, test.SetRSOwnerRef),
 					},
 				},
 				n3NodeName: {},
@@ -349,38 +323,38 @@ func TestLowNodeUtilization(t *testing.T) {
 			nodes: map[string]*v1.Node{
 				n1NodeName: test.BuildTestNode(n1NodeName, 4000, 3000, 9, nil),
 				n2NodeName: test.BuildTestNode(n2NodeName, 4000, 3000, 10, nil),
-				n3NodeName: test.BuildTestNode(n3NodeName, 4000, 3000, 10, setNodeUnschedulable),
+				n3NodeName: test.BuildTestNode(n3NodeName, 4000, 3000, 10, test.SetNodeUnschedulable),
 			},
 			// All pods are assumed to be burstable (test.BuildTestNode always sets both cpu/memory resource requests to some value)
 			pods: map[string]*v1.PodList{
 				n1NodeName: {
 					Items: []v1.Pod{
 						*test.BuildTestPod("p1", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setRSOwnerRef(pod)
-							makeBestEffortPod(pod)
+							test.SetRSOwnerRef(pod)
+							test.MakeBestEffortPod(pod)
 						}),
 						*test.BuildTestPod("p2", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setRSOwnerRef(pod)
-							makeBestEffortPod(pod)
+							test.SetRSOwnerRef(pod)
+							test.MakeBestEffortPod(pod)
 						}),
 						*test.BuildTestPod("p3", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setRSOwnerRef(pod)
+							test.SetRSOwnerRef(pod)
 						}),
 						*test.BuildTestPod("p4", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setRSOwnerRef(pod)
-							makeBestEffortPod(pod)
+							test.SetRSOwnerRef(pod)
+							test.MakeBestEffortPod(pod)
 						}),
 						*test.BuildTestPod("p5", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setRSOwnerRef(pod)
-							makeBestEffortPod(pod)
+							test.SetRSOwnerRef(pod)
+							test.MakeBestEffortPod(pod)
 						}),
 						// These won't be evicted.
 						*test.BuildTestPod("p6", 400, 0, n1NodeName, func(pod *v1.Pod) {
-							setDSOwnerRef(pod)
+							test.SetDSOwnerRef(pod)
 						}),
 						*test.BuildTestPod("p7", 400, 0, n1NodeName, func(pod *v1.Pod) {
 							// A pod with local storage.
-							setNormalOwnerRef(pod)
+							test.SetNormalOwnerRef(pod)
 							pod.Spec.Volumes = []v1.Volume{
 								{
 									Name: "sample",
@@ -404,7 +378,7 @@ func TestLowNodeUtilization(t *testing.T) {
 				},
 				n2NodeName: {
 					Items: []v1.Pod{
-						*test.BuildTestPod("p9", 400, 0, n1NodeName, setRSOwnerRef),
+						*test.BuildTestPod("p9", 400, 0, n1NodeName, test.SetRSOwnerRef),
 					},
 				},
 				n3NodeName: {},
@@ -495,44 +469,6 @@ func TestLowNodeUtilization(t *testing.T) {
 	}
 }

-func TestSortPodsByPriority(t *testing.T) {
-	n1 := test.BuildTestNode("n1", 4000, 3000, 9, nil)
-
-	p1 := test.BuildTestPod("p1", 400, 0, n1.Name, setLowPriority)
-
-	// BestEffort
-	p2 := test.BuildTestPod("p2", 400, 0, n1.Name, func(pod *v1.Pod) {
-		setHighPriority(pod)
-		makeBestEffortPod(pod)
-	})
-
-	// Burstable
-	p3 := test.BuildTestPod("p3", 400, 0, n1.Name, func(pod *v1.Pod) {
-		setHighPriority(pod)
-		makeBurstablePod(pod)
-	})
-
-	// Guaranteed
-	p4 := test.BuildTestPod("p4", 400, 100, n1.Name, func(pod *v1.Pod) {
-		setHighPriority(pod)
-		makeGuaranteedPod(pod)
-	})
-
-	// Best effort with nil priorities.
-	p5 := test.BuildTestPod("p5", 400, 100, n1.Name, makeBestEffortPod)
-	p5.Spec.Priority = nil
-
-	p6 := test.BuildTestPod("p6", 400, 100, n1.Name, makeGuaranteedPod)
-	p6.Spec.Priority = nil
-
-	podList := []*v1.Pod{p4, p3, p2, p1, p6, p5}
-
-	sortPodsBasedOnPriority(podList)
-	if !reflect.DeepEqual(podList[len(podList)-1], p4) {
-		t.Errorf("Expected last pod in sorted list to be %v which of highest priority and guaranteed but got %v", p4, podList[len(podList)-1])
-	}
-}
-
 func TestValidateStrategyConfig(t *testing.T) {
 	tests := []struct {
 		name             string
@@ -783,7 +719,7 @@ func TestWithTaints(t *testing.T) {
 		},
 	}

-	podThatToleratesTaint := test.BuildTestPod("tolerate_pod", 200, 0, n1.Name, setRSOwnerRef)
+	podThatToleratesTaint := test.BuildTestPod("tolerate_pod", 200, 0, n1.Name, test.SetRSOwnerRef)
 	podThatToleratesTaint.Spec.Tolerations = []v1.Toleration{
 		{
 			Key:   "key",
@@ -802,16 +738,16 @@ func TestWithTaints(t *testing.T) {
 			nodes: []*v1.Node{n1, n2, n3},
 			pods: []*v1.Pod{
 				//Node 1 pods
-				test.BuildTestPod(fmt.Sprintf("pod_1_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_2_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_3_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_4_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_5_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_6_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_7_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_8_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_1_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_2_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_3_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_4_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_5_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_6_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_7_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_8_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
 				// Node 2 pods
-				test.BuildTestPod(fmt.Sprintf("pod_9_%s", n2.Name), 200, 0, n2.Name, setRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_9_%s", n2.Name), 200, 0, n2.Name, test.SetRSOwnerRef),
 			},
 			evictionsExpected: 1,
 		},
@@ -820,16 +756,16 @@ func TestWithTaints(t *testing.T) {
 			nodes: []*v1.Node{n1, n3withTaints},
 			pods: []*v1.Pod{
 				//Node 1 pods
-				test.BuildTestPod(fmt.Sprintf("pod_1_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_2_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_3_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_4_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_5_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_6_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_7_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_8_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_1_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_2_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_3_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_4_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_5_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_6_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_7_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_8_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
 				// Node 3 pods
-				test.BuildTestPod(fmt.Sprintf("pod_9_%s", n3withTaints.Name), 200, 0, n3withTaints.Name, setRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_9_%s", n3withTaints.Name), 200, 0, n3withTaints.Name, test.SetRSOwnerRef),
 			},
 			evictionsExpected: 0,
 		},
@@ -838,16 +774,16 @@ func TestWithTaints(t *testing.T) {
 			nodes: []*v1.Node{n1, n3withTaints},
 			pods: []*v1.Pod{
 				//Node 1 pods
-				test.BuildTestPod(fmt.Sprintf("pod_1_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_2_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_3_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_4_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_5_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_6_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
-				test.BuildTestPod(fmt.Sprintf("pod_7_%s", n1.Name), 200, 0, n1.Name, setRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_1_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_2_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_3_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_4_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_5_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_6_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_7_%s", n1.Name), 200, 0, n1.Name, test.SetRSOwnerRef),
 				podThatToleratesTaint,
 				// Node 3 pods
-				test.BuildTestPod(fmt.Sprintf("pod_9_%s", n3withTaints.Name), 200, 0, n3withTaints.Name, setRSOwnerRef),
+				test.BuildTestPod(fmt.Sprintf("pod_9_%s", n3withTaints.Name), 200, 0, n3withTaints.Name, test.SetRSOwnerRef),
 			},
 			evictionsExpected: 1,
 		},
--- a/pkg/descheduler/strategies/pod_antiaffinity.go
+++ b/pkg/descheduler/strategies/pod_antiaffinity.go
@@ -37,6 +37,8 @@ func RemovePodsViolatingInterPodAntiAffinity(ctx context.Context, client clients
 		if err != nil {
 			return
 		}
+		// sort the evictable Pods based on priority, if there are multiple pods with same priority, they are sorted based on QoS tiers.
+		podutil.SortPodsBasedOnPriorityLowToHigh(pods)
 		totalPods := len(pods)
 		for i := 0; i < totalPods; i++ {
 			if checkPodsWithAntiAffinityExist(pods[i], pods) {
--- a/pkg/descheduler/strategies/pod_antiaffinity_test.go
+++ b/pkg/descheduler/strategies/pod_antiaffinity_test.go
@@ -37,16 +37,33 @@ func TestPodAntiAffinity(t *testing.T) {
 	p2 := test.BuildTestPod("p2", 100, 0, node.Name, nil)
 	p3 := test.BuildTestPod("p3", 100, 0, node.Name, nil)
 	p4 := test.BuildTestPod("p4", 100, 0, node.Name, nil)
+	p5 := test.BuildTestPod("p5", 100, 0, node.Name, nil)
+	p6 := test.BuildTestPod("p6", 100, 0, node.Name, nil)
+	p7 := test.BuildTestPod("p7", 100, 0, node.Name, nil)
 	p2.Labels = map[string]string{"foo": "bar"}
-	p1.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
-	p2.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
-	p3.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
-	p4.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
+	p5.Labels = map[string]string{"foo": "bar"}
+	p6.Labels = map[string]string{"foo": "bar"}
+	p7.Labels = map[string]string{"foo1": "bar1"}
+	test.SetNormalOwnerRef(p1)
+	test.SetNormalOwnerRef(p2)
+	test.SetNormalOwnerRef(p3)
+	test.SetNormalOwnerRef(p4)
+	test.SetNormalOwnerRef(p5)
+	test.SetNormalOwnerRef(p6)
+	test.SetNormalOwnerRef(p7)

 	// set pod anti affinity
-	setPodAntiAffinity(p1)
-	setPodAntiAffinity(p3)
-	setPodAntiAffinity(p4)
+	setPodAntiAffinity(p1, "foo", "bar")
+	setPodAntiAffinity(p3, "foo", "bar")
+	setPodAntiAffinity(p4, "foo", "bar")
+	setPodAntiAffinity(p5, "foo1", "bar1")
+	setPodAntiAffinity(p6, "foo1", "bar1")
+	setPodAntiAffinity(p7, "foo", "bar")
+
+	// set pod priority
+	test.SetPodPriority(p5, 100)
+	test.SetPodPriority(p6, 50)
+	test.SetPodPriority(p7, 0)

 	tests := []struct {
 		description             string
@@ -66,13 +83,19 @@ func TestPodAntiAffinity(t *testing.T) {
 			pods:                    []v1.Pod{*p1, *p2, *p3, *p4},
 			expectedEvictedPodCount: 3,
 		},
+		{
+			description:             "Evict only 1 pod after sorting",
+			maxPodsToEvict:          0,
+			pods:                    []v1.Pod{*p5, *p6, *p7},
+			expectedEvictedPodCount: 1,
+		},
 	}

 	for _, test := range tests {
 		// create fake client
 		fakeClient := &fake.Clientset{}
 		fakeClient.Fake.AddReactor("list", "pods", func(action core.Action) (bool, runtime.Object, error) {
-			return true, &v1.PodList{Items: []v1.Pod{*p1, *p2, *p3, *p4}}, nil
+			return true, &v1.PodList{Items: test.pods}, nil
 		})
 		fakeClient.Fake.AddReactor("get", "nodes", func(action core.Action) (bool, runtime.Object, error) {
 			return true, node, nil
@@ -95,7 +118,7 @@ func TestPodAntiAffinity(t *testing.T) {
 	}
 }

-func setPodAntiAffinity(inputPod *v1.Pod) {
+func setPodAntiAffinity(inputPod *v1.Pod, labelKey, labelValue string) {
 	inputPod.Spec.Affinity = &v1.Affinity{
 		PodAntiAffinity: &v1.PodAntiAffinity{
 			RequiredDuringSchedulingIgnoredDuringExecution: []v1.PodAffinityTerm{
@@ -103,9 +126,9 @@ func setPodAntiAffinity(inputPod *v1.Pod) {
 					LabelSelector: &metav1.LabelSelector{
 						MatchExpressions: []metav1.LabelSelectorRequirement{
 							{
-								Key:      "foo",
+								Key:      labelKey,
 								Operator: metav1.LabelSelectorOpIn,
-								Values:   []string{"bar"},
+								Values:   []string{labelValue},
 							},
 						},
 					},
--- a/test/test_utils.go
+++ b/test/test_utils.go
@@ -116,3 +116,48 @@ func BuildTestNode(name string, millicpu int64, mem int64, pods int64, apply fun
 	}
 	return node
 }
+
+// MakeBestEffortPod makes the given pod a BestEffort pod
+func MakeBestEffortPod(pod *v1.Pod) {
+	pod.Spec.Containers[0].Resources.Requests = nil
+	pod.Spec.Containers[0].Resources.Requests = nil
+	pod.Spec.Containers[0].Resources.Limits = nil
+	pod.Spec.Containers[0].Resources.Limits = nil
+}
+
+// MakeBurstablePod makes the given pod a Burstable pod
+func MakeBurstablePod(pod *v1.Pod) {
+	pod.Spec.Containers[0].Resources.Limits = nil
+	pod.Spec.Containers[0].Resources.Limits = nil
+}
+
+// MakeGuaranteedPod makes the given pod an Guaranteed pod
+func MakeGuaranteedPod(pod *v1.Pod) {
+	pod.Spec.Containers[0].Resources.Limits[v1.ResourceCPU] = pod.Spec.Containers[0].Resources.Requests[v1.ResourceCPU]
+	pod.Spec.Containers[0].Resources.Limits[v1.ResourceMemory] = pod.Spec.Containers[0].Resources.Requests[v1.ResourceMemory]
+}
+
+// SetRSOwnerRef sets the given pod's owner to ReplicaSet
+func SetRSOwnerRef(pod *v1.Pod) {
+	pod.ObjectMeta.OwnerReferences = GetReplicaSetOwnerRefList()
+}
+
+// SetDSOwnerRef sets the given pod's owner to DaemonSet
+func SetDSOwnerRef(pod *v1.Pod) {
+	pod.ObjectMeta.OwnerReferences = GetDaemonSetOwnerRefList()
+}
+
+// SetNormalOwnerRef sets the given pod's owner to Pod
+func SetNormalOwnerRef(pod *v1.Pod) {
+	pod.ObjectMeta.OwnerReferences = GetNormalPodOwnerRefList()
+}
+
+// SetPodPriority sets the given pod's priority
+func SetPodPriority(pod *v1.Pod, priority int32) {
+	pod.Spec.Priority = &priority
+}
+
+// SetNodeUnschedulable sets the given node unschedulable
+func SetNodeUnschedulable(node *v1.Node) {
+	node.Spec.Unschedulable = true
+}