feat(metrics): add model_name label to PD decision metric

pkg/metrics/metrics.go

@@ -25,7 +25,7 @@ var (
 			Name:      "pd_decision_total",
 			Help:      metrics.HelpMsgWithStability("Total number of P/D disaggregation decisions made", compbasemetrics.ALPHA),
 		},
-		[]string{"decision_type"}, // "decode-only" or "prefill-decode"
+		[]string{"model_name", "decision_type"}, // "decode-only" or "prefill-decode"
 	)
 )
 
@@ -36,7 +36,13 @@ func GetCollectors() []prometheus.Collector {
 	}
 }
 
-// RecordPDDecision records the type of P/D disaggregation decision made.
-func RecordPDDecision(decisionType string) {
-	SchedulerPDDecisionCount.WithLabelValues(decisionType).Inc()
+// RecordPDDecision increments the counter for a specific P/D routing decision.
+// The decisionType must be one of the DecisionType* constants (e.g., DecisionTypeDecodeOnly).
+// The model parameter should be the target model name (e.g., from request.TargetModel);
+// if empty, the caller should pass a placeholder like "unknown" to avoid empty labels.
+func RecordPDDecision(modelName, decisionType string) {
+	if modelName == "" {
+		modelName = "unknown"
+	}
+	SchedulerPDDecisionCount.WithLabelValues(modelName, decisionType).Inc()
 }

pkg/metrics/metrics_test.go

@@ -8,15 +8,20 @@ import (
 )
 
 func TestSchedulerPDDecisionCount(t *testing.T) {
-	RecordPDDecision(DecisionTypePrefillDecode)
-	RecordPDDecision(DecisionTypeDecodeOnly)
-	RecordPDDecision(DecisionTypePrefillDecode)
-	if err := testutil.CollectAndCompare(SchedulerPDDecisionCount, strings.NewReader(`
+	model := "test-model"
+
+	RecordPDDecision(model, DecisionTypePrefillDecode)
+	RecordPDDecision(model, DecisionTypeDecodeOnly)
+	RecordPDDecision(model, DecisionTypePrefillDecode)
+	expected := `
 		# HELP llm_d_inference_scheduler_pd_decision_total [ALPHA] Total number of P/D disaggregation decisions made
 		# TYPE llm_d_inference_scheduler_pd_decision_total counter
-		llm_d_inference_scheduler_pd_decision_total{decision_type="decode-only"} 1
-		llm_d_inference_scheduler_pd_decision_total{decision_type="prefill-decode"} 2
-	`), "decision_type"); err != nil {
+		llm_d_inference_scheduler_pd_decision_total{decision_type="decode-only",model_name="test-model"} 1
+		llm_d_inference_scheduler_pd_decision_total{decision_type="prefill-decode",model_name="test-model"} 2
+	`
+
+	if err := testutil.CollectAndCompare(SchedulerPDDecisionCount, strings.NewReader(expected),
+		"llm_d_inference_scheduler_pd_decision_total"); err != nil {
 		t.Errorf("RecordPDDecision() failed: %v", err)
 	}
 }

pkg/plugins/profile/pd_profile_handler.go

@@ -163,12 +163,12 @@ func (h *PdProfileHandler) Pick(ctx context.Context, cycleState *types.CycleStat
 
 		if (1.0-hitPercentagePrefix)*float64(len(userInput)) < float64(h.pdThreshold) {
 			log.FromContext(ctx).Info("Non-cached suffix is smaller than threshold, using decode profile only", "hitPercentage", hitPercentagePrefix)
-			metrics.RecordPDDecision(metrics.DecisionTypeDecodeOnly)
+			metrics.RecordPDDecision(request.TargetModel, metrics.DecisionTypeDecodeOnly)
 			return map[string]*framework.SchedulerProfile{} // do not run prefill
 		}
 	}
 
-	metrics.RecordPDDecision(metrics.DecisionTypePrefillDecode)
+	metrics.RecordPDDecision(request.TargetModel, metrics.DecisionTypePrefillDecode)
 	// run the prefill profile
 	return map[string]*framework.SchedulerProfile{
 		h.prefillProfile: profiles[h.prefillProfile],