TAS: introduce dedicated TAS label

apis/kueue/v1alpha1/tas_types.go

@@ -52,6 +52,11 @@ const (
 	// of the PodSet of the admitted Workload corresponding to the PodTemplate.
 	// The label is set when starting the Job, and removed on stopping the Job.
 	PodSetLabel = "kueue.x-k8s.io/podset"
+
+	// TASLabel is a label set on the Job's PodTemplate to indicate that the
+	// PodSet is admitted using TopologyAwareScheduling, and all Pods created
+	// from the Job's PodTemplate also have the label.
+	TASLabel = "kueue.x-k8s.io/tas"
 )
 
 // TopologySpec defines the desired state of Topology

keps/2724-topology-aware-schedling/README.md

@@ -46,6 +46,7 @@
   - [Workload API alternatives](#workload-api-alternatives)
     - [Drop the topologyAssignment.levels field](#drop-the-topologyassignmentlevels-field)
     - [Rename the topologyAssignment.domains.values field as levelValues](#rename-the-topologyassignmentdomainsvalues-field-as-levelvalues)
+  - [Drop dedicated TAS label](#drop-dedicated-tas-label)
 <!-- /toc -->
 
 ## Summary
@@ -564,6 +565,11 @@ const (
   // of the PodSet of the admitted Workload corresponding to the PodTemplate.
   // The label is set when starting the Job, and removed on stopping the Job.
   PodSetLabel = "kueue.x-k8s.io/podset"
+
+  // TASLabel is a label set on the Job's PodTemplate to indicate that the
+  // PodSet is admitted using TopologyAwareScheduling, and all Pods created
+  // from the Job's PodTemplate also have the label.
+  TASLabel = "kueue.x-k8s.io/tas"
 )
 ```
 
@@ -686,6 +692,7 @@ The new validations which are for MVP, but likely will be relaxed in the future:
   ReplicatedJob level (see [Story 2](#story-2))
 - re-evaluate the need to support for "preferred/required" preferences at the
   Workload level (see [Story 3](#story-3))
+- re-evaluate the need for the `kueue.x-k8s.io/tas`
 
 #### Stable
 
@@ -864,3 +871,18 @@ it specifies values for the keys in the `levels` field.
 * the field is on Workload API, which is generally not a user-facing API in
   Kueue. Workload objects are meant for the internal mechanics of Kueue.
 * the intention of the field can be expressed in a comment.
+
+### Drop dedicated TAS label
+
+We could reduce the API surface by dropping the TAS label. The label is going
+to be used in two places:
+1. in TopologyUngater to quickly skip non-TAS pods in the events handler
+2. when accounting for usage from Pods to quickly list only non-TAS pods
+
+However, it was pointed out in discussions that the use case could probably be
+fulfilled with a dedicated indexed virtual field.
+
+**Reasons for discarding/deferring**
+
+Increased code complexity which could defer the 0.9 release for the Alpha
+version. We will re-evaluate the need for the label before the Beta release.

pkg/podset/podset.go

@@ -63,6 +63,7 @@ func FromAssignment(ctx context.Context, client client.Client, assignment *kueue
 		Annotations:  make(map[string]string),
 	}
 	if features.Enabled(features.TopologyAwareScheduling) && assignment.TopologyAssignment != nil {
+		info.Labels[kueuealpha.TASLabel] = "true"
 		info.SchedulingGates = append(info.SchedulingGates, corev1.PodSchedulingGate{
 			Name: kueuealpha.TopologySchedulingGate,
 		})

pkg/podset/podset_test.go

@@ -188,6 +188,9 @@ func TestFromAssignment(t *testing.T) {
 			wantInfo: PodSetInfo{
 				Name:  "name",
 				Count: 4,
+				Labels: map[string]string{
+					kueuealpha.TASLabel: "true",
+				},
 				NodeSelector: map[string]string{
 					"f1l1": "f1v1",
 					"f1l2": "f1v2",
@@ -428,6 +431,25 @@ func TestMergeRestore(t *testing.T) {
 				Obj(),
 			wantRestoreChanges: true,
 		},
+		"podset with tas label; empty info": {
+			podSet: utiltesting.MakePodSet("", 1).
+				Labels(map[string]string{kueuealpha.TASLabel: "true"}).
+				Obj(),
+			wantPodSet: utiltesting.MakePodSet("", 1).
+				Labels(map[string]string{kueuealpha.TASLabel: "true"}).
+				Obj(),
+		},
+		"podset with tas label; info re-adds the same": {
+			podSet: utiltesting.MakePodSet("", 1).
+				Labels(map[string]string{kueuealpha.TASLabel: "true"}).
+				Obj(),
+			info: PodSetInfo{
+				Labels: map[string]string{kueuealpha.TASLabel: "true"},
+			},
+			wantPodSet: utiltesting.MakePodSet("", 1).
+				Labels(map[string]string{kueuealpha.TASLabel: "true"}).
+				Obj(),
+		},
 	}
 
 	for name, tc := range cases {