private Duration getExecutionTimeSliceForDriverTask(DriverTask driverTask) {
    if (driverTask.isHighestPriority()) {
      // highestPriorityTask has the same time slice as level0 task
      return TIME_SLICE_FOR_EACH_LEVEL[0];
    }
    // no need to check whether the level of DriverTask is out of bound since it has been checked
    // when DriverTask is polled out from MultiLevelPriorityQueue
    return TIME_SLICE_FOR_EACH_LEVEL[driverTask.getPriority().getLevel()];
  }
In multi-level feedback queue, levels with lower priority have longer time slices. Currently,
we assign (level + 1) * TimeSliceUnit to each level.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/schedule/DriverTaskThread.java