我针对HDFS运行了Hive查询。除CPU时间外，所有似乎都运行正常。为什么CPU时间为0毫秒？
Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 1
2015-11-29 23:18:20,219 Stage-1 map = 0%, reduce = 0%
2015-11-29 23:18:25,344 Stage-1 map = 100%, reduce = 0%
2015-11-29 23:18:30,472 Stage-1 map = 100%, reduce = 100%
Ended Job = job_1448857017878_0002
MapReduce Jobs Launched:
Stage-Stage-1: Map: 1 Reduce: 1 HDFS Read: 8016880 HDFS Write: 156 SUCCESS
Total MapReduce CPU Time Spent: 0 msec