enable for event loop metric

Author: shangm2

presto-common/src/main/java/com/facebook/presto/common/RuntimeStats.java

@@ -95,6 +95,11 @@ public void addMetricValue(String name, RuntimeUnit unit, long value)
         metrics.computeIfAbsent(name, k -> new RuntimeMetric(name, unit)).addValue(value);
     }
 
+    public void addMetricValue(String name, RuntimeUnit unit, long value, boolean trackPercentiles)
+    {
+        metrics.computeIfAbsent(name, k -> new RuntimeMetric(name, unit, trackPercentiles)).addValue(value);
+    }
+
     public void addMetricValueIgnoreZero(String name, RuntimeUnit unit, long value)
     {
         if (value == 0) {

presto-main-base/src/main/java/com/facebook/presto/execution/StageExecutionStateMachine.java

@@ -437,7 +437,7 @@ public void recordTaskUpdateDeliveredTime(long nanos)
     @Override
     public void recordStartWaitForEventLoop(long nanos)
     {
-        runtimeStats.addMetricValue(TASK_START_WAIT_FOR_EVENT_LOOP, NANO, max(nanos, 0));
+        runtimeStats.addMetricValue(TASK_START_WAIT_FOR_EVENT_LOOP, NANO, max(nanos, 0), true);
     }
 
     public void recordDeliveredUpdates(int updates)