normalize score to make sure it is always in the range of [0,1] (kubernetes-sigs#1236)

* normalize score to make sure score is always in the range of [0,1]

Signed-off-by: Nir Rozenbaum <[email protected]>

* code review commentsx

Signed-off-by: Nir Rozenbaum <[email protected]>

---------

Signed-off-by: Nir Rozenbaum <[email protected]>

Author: nirrozenbaum

pkg/epp/scheduling/framework/plugins.go

@@ -57,6 +57,8 @@ type Filter interface {
 
 // Scorer defines the interface for scoring a list of pods based on context.
 // Scorers must score pods with a value within the range of [0,1] where 1 is the highest score.
+// If a scorer returns value greater than 1, it will be treated as score 1.
+// If a scorer returns value lower than 0, it will be treated as score 0.
 type Scorer interface {
 	plugins.Plugin
 	Score(ctx context.Context, cycleState *types.CycleState, request *types.LLMRequest, pods []types.Pod) map[types.Pod]float64

pkg/epp/scheduling/framework/scheduler_profile.go

@@ -180,7 +180,7 @@ func (p *SchedulerProfile) runScorerPlugins(ctx context.Context, request *types.
 		scores := scorer.Score(ctx, cycleState, request, pods)
 		metrics.RecordSchedulerPluginProcessingLatency(ScorerPluginType, scorer.TypedName().Type, time.Since(before))
 		for pod, score := range scores { // weight is relative to the sum of weights
-			weightedScorePerPod[pod] += score * float64(scorer.Weight())
+			weightedScorePerPod[pod] += enforceScoreRange(score) * float64(scorer.Weight())
 		}
 		loggerDebug.Info("After running scorer", "scorer", scorer.TypedName().Type)
 	}
@@ -215,3 +215,13 @@ func (p *SchedulerProfile) runPostCyclePlugins(ctx context.Context, cycleState *
 		metrics.RecordSchedulerPluginProcessingLatency(PostCyclePluginType, plugin.TypedName().Type, time.Since(before))
 	}
 }
+
+func enforceScoreRange(score float64) float64 {
+	if score < 0 {
+		return 0
+	}
+	if score > 1 {
+		return 1
+	}
+	return score
+}