Distinguish between Preemption due to reclamation and fair sharing

pkg/scheduler/preemption/preemption.go

@@ -162,8 +162,20 @@ func canBorrowWithinCohort(cq *cache.ClusterQueue, wl *kueue.Workload) (bool, *i
 	return true, &threshold
 }
 
+const (
+	// ClusterQueueOrigin indicates that preemption originated from cluster queue
+	ClusterQueueOrigin = "ClusterQueue"
+	// CohortOrigin indicates that preemption originated from cohort
+	CohortOrigin = "cohort"
+
+	InClusterQueueReason = "InClusterQueue"
+
+	InCohortReclamationReason = "InCohortReclamation"
+	InCohortFairSharingReason = "InCohortFairSharing"
+)
+
 // IssuePreemptions marks the target workloads as evicted.
-func (p *Preemptor) IssuePreemptions(ctx context.Context, preemptor *workload.Info, targets []*workload.Info, cq *cache.ClusterQueue) (int, error) {
+func (p *Preemptor) IssuePreemptions(ctx context.Context, preemptor *workload.Info, targets []*workload.Info, cq *cache.ClusterQueue, reclamation bool) (int, error) {
 	log := ctrl.LoggerFrom(ctx)
 	errCh := routine.NewErrorChannel()
 	ctx, cancel := context.WithCancel(ctx)
@@ -172,11 +184,16 @@ func (p *Preemptor) IssuePreemptions(ctx context.Context, preemptor *workload.In
 	workqueue.ParallelizeUntil(ctx, parallelPreemptions, len(targets), func(i int) {
 		target := targets[i]
 		if !meta.IsStatusConditionTrue(target.Obj.Status.Conditions, kueue.WorkloadEvicted) {
-			origin := "ClusterQueue"
-			reason := "InClusterQueue"
+			origin := ClusterQueueOrigin
+			reason := InClusterQueueReason
 			if cq.Name != target.ClusterQueue {
-				origin = "cohort"
-				reason = "InCohort"
+				origin = CohortOrigin
+				if p.enableFairSharing {
+					reason = InCohortFairSharingReason
+				}
+				if reclamation {
+					reason = InCohortReclamationReason
+				}
 			}
 
 			message := fmt.Sprintf("Preempted to accommodate a workload (UID: %s) in the %s", preemptor.Obj.UID, origin)

pkg/scheduler/scheduler.go

@@ -248,7 +248,7 @@ func (s *Scheduler) schedule(ctx context.Context) wait.SpeedSignal {
 			if len(e.preemptionTargets) != 0 {
 				// If preemptions are issued, the next attempt should try all the flavors.
 				e.LastAssignment = nil
-				preempted, err := s.preemptor.IssuePreemptions(ctx, &e.Info, e.preemptionTargets, cq)
+				preempted, err := s.preemptor.IssuePreemptions(ctx, &e.Info, e.preemptionTargets, cq, e.assignment.Borrowing)
 				if err != nil {
 					log.Error(err, "Failed to preempt workloads")
 				}