--- old/src/hotspot/share/gc/serial/serialHeap.cpp	2020-04-25 22:41:14.025518278 +0800
+++ new/src/hotspot/share/gc/serial/serialHeap.cpp	2020-04-25 22:41:13.841519097 +0800
@@ -90,3 +90,10 @@
   memory_pools.append(_old_pool);
   return memory_pools;
 }
+
+// No workGang for SerialHeap, work serially with thread 0
+Tickspan SerialHeap::run_task(AbstractGangTask* task) {
+  Ticks start = Ticks::now();
+  task->work(0);
+  return Ticks::now() - start;
+}