I am running a Hadoop MapReduce job, getting input files from HDFS or Amazon S3. I am wondering if it's possible to know how long does it take for a mapper task to read file from HDFS or S3 to the mapper. I'd like to know the time just for reading data, not include mapper processing time of those data. The result I am looking for is something like MB/second for a certain mapper task, which indicates how fast the mapper can read from HDFS or S3. It's something like a I/O performance.
Thanks.