Latency and speed of HDFS

[Pei HE]

Hi all,
I want to know the detailed performance of Hadoop.

I am writing a client code to test the latency, transfer speed of
HDFS, and the time of initiating a JVM for a task.

Does anyone know that which classes can be called without running a
whole map/reduce job to find out the performance of Hadoop?

I am trying to create a DFSClient in the following way.
                Configuration conf = new Configuration();
                DFSClient client = new DFSClient(conf);
                client.exists("hdfs://localhost:9900/home/");
But, a RemoteException was thrown.

Could anyone help me about that?

Thanks
--
Pei