- updated scorer interface comment to mention constraint on scores

- normalization in kvcache-aware-scorer

Signed-off-by: Maroon Ayoub <maroonay@gmail.com>

Author: vMaroon

pkg/epp/scheduling/plugins/scorers/kvcache-aware-scorer.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"math"
 	"os"
 	"time"
 
@@ -111,11 +112,33 @@ func (s *KVCacheAwareScorer) Score(ctx *types.Context, pod types.Pod) (float64,
 
 	// update the cache
 	s.scoresCache = make(map[string]float64, len(scores))
+	minScore := math.MaxFloat64
+	maxScore := 0.0
 	for _, pod := range scores {
 		s.scoresCache[pod.Name] = pod.Score
+
+		// maintain min and max to normalize later
+		if pod.Score < minScore {
+			minScore = pod.Score
+		}
+
+		if pod.Score > maxScore {
+			maxScore = pod.Score
+		}
 	}
+	// normalize scores
+	s.scoresCache = normalizeScores(s.scoresCache, minScore, maxScore)
+
 	s.scoresCacheLastUpdate = time.Now()
 	loggerDebug.Info("Updated scores cache", "time", s.scoresCacheLastUpdate, "pods", s.scoresCache)
 
 	return s.scoresCache[pod.GetPod().Address], nil
 }
+
+func normalizeScores(scores map[string]float64, minScore, maxScore float64) map[string]float64 {
+	normalizedScores := make(map[string]float64, len(scores))
+	for podName, score := range scores {
+		normalizedScores[podName] = (score - minScore) / (maxScore - minScore)
+	}
+	return normalizedScores
+}

pkg/epp/scheduling/types/interfaces.go

@@ -63,6 +63,7 @@ type Filter interface {
 }
 
 // Scorer defines the interface for scoring pods based on context.
+// Scorers must return a score between 0 and 1, where 1 is the best score.
 type Scorer interface {
 	Plugin
 	Score(ctx *Context, pod Pod) (float64, error)