optimize: shedding algorithm performance (#3908)

rest/config.go

@@ -53,7 +53,7 @@ type (
 		MaxBytes int64  `json:",default=1048576"`
 		// milliseconds
 		Timeout      int64         `json:",default=3000"`
-		CpuThreshold int64         `json:",default=900,range=[0:1000]"`
+		CpuThreshold int64         `json:",default=900,range=[0:1000)"`
 		Signature    SignatureConf `json:",optional"`
 		// There are default values for all the items in Middlewares.
 		Middlewares MiddlewaresConf

rest/handler/prometheushandler.go

@@ -18,7 +18,7 @@ var (
 		Name:      "duration_ms",
 		Help:      "http server requests duration(ms).",
 		Labels:    []string{"path", "method"},
-		Buckets:   []float64{5, 10, 25, 50, 100, 250, 500, 1000},
+		Buckets:   []float64{5, 10, 25, 50, 100, 250, 500, 750, 1000},
 	})
 
 	metricServerReqCodeTotal = metric.NewCounterVec(&metric.CounterVecOpts{