fix: added check for hostname to minimize bin-packing compute

Signed-off-by: MenD32 <[email protected]>

Author: MenD32

cluster-autoscaler/estimator/binpacking_estimator.go

@@ -186,7 +186,7 @@ func (e *BinpackingNodeEstimator) tryToScheduleOnNewNodes(
 			// The pod can't be scheduled on the newly created node because of scheduling predicates.
 
 			// Check if node failed because of topology constraints.
-			if hasTopologyConstraintError(err) {
+			if isPodUsingHostNameTopologyKey(pod) && hasTopologyConstraintError(err) {
 				// If the pod can't be scheduled on the last node because of topology constraints, we can stop binpacking.
 				// The pod can't be scheduled on any new node either, because it has the same topology constraints.
 				nodeName, err := e.clusterSnapshot.SchedulePodOnAnyNodeMatching(pod, func(nodeInfo *framework.NodeInfo) bool {
@@ -273,6 +273,22 @@ func hasTopologyConstraintError(err clustersnapshot.SchedulingError) bool {
 	return slices.Contains(err.FailingPredicateReasons(), podtopologyspread.ErrReasonConstraintsNotMatch)
 }
 
+// isPodUsingHostNameTopoKey returns true if the pod has any topology spread
+// constraint that uses the kubernetes.io/hostname topology key
+func isPodUsingHostNameTopologyKey(pod *apiv1.Pod) bool {
+	if pod == nil || pod.Spec.TopologySpreadConstraints == nil {
+		return false
+	}
+
+	for _, constraint := range pod.Spec.TopologySpreadConstraints {
+		if constraint.TopologyKey == apiv1.LabelHostname {
+			return true
+		}
+	}
+
+	return false
+}
+
 func observeBinpackingHeterogeneity(podsEquivalenceGroups []PodEquivalenceGroup, nodeTemplate *framework.NodeInfo) {
 	node := nodeTemplate.Node()
 	var instanceType, cpuCount string

cluster-autoscaler/estimator/binpacking_estimator_test.go

@@ -172,7 +172,7 @@ func TestBinpackingEstimate(t *testing.T) {
 			expectProcessedPods: highResourcePodGroup.Pods,
 		},
 		{
-			name:       "hostname topology spreading with maxSkew=2 forces 2 pods/node",
+			name:       "hostname topology spreading with maxSkew=2 allows 8 pods to schedule retroactively",
 			millicores: 1000,
 			memory:     5000,
 			podsEquivalenceGroup: []PodEquivalenceGroup{makePodEquivalenceGroup(
@@ -195,8 +195,8 @@ func TestBinpackingEstimate(t *testing.T) {
 			podsEquivalenceGroup: []PodEquivalenceGroup{makePodEquivalenceGroup(
 				BuildTestPod(
 					"estimatee",
-					200,
-					200,
+					20,
+					100,
 					WithNamespace("universe"),
 					WithLabels(map[string]string{
 						"app": "estimatee",