fix cpu recommend zero

Author: mervynwang

pkg/prediction/percentile/prediction.go

@@ -71,7 +71,7 @@ func (p *percentilePrediction) getPredictedValuesFromSignals(queryExpr string, s
 
 	if cfg.aggregated {
 		signal := signals[keyAll]
-		if signal != nil {
+		if signal != nil && signal.totalSamplesCount > 0 {
 			sample := common.Sample{
 				Value:     estimator.GetEstimation(signal.histogram),
 				Timestamp: now,

pkg/recommendation/recommender/resource/recommend.go

@@ -131,7 +131,9 @@ func (rr *ResourceRecommender) Recommend(ctx *framework.RecommendationContext) e
 				pr.Target[corev1.ResourceMemory] = memQuantity.String()
 			}
 
-			resourceRecommendation.Pod = &pr
+			if len(pr.Target) != 0 {
+				resourceRecommendation.Pod = &pr
+			}
 		} else {
 			klog.V(4).Infof("not use pod metrics for pod %s", ctx.Pods[0].Name)
 		}