title: GetDirectBufferAddress does not perform better than GetDoubleArrayElements
body: <p>I am sending large amounts of data from Java to C++ using JNI and in an attempt to minimize the cost of transferring the data and avoid unnecessary copies, I tried implementing GetDirectBufferAddress to access the memory location directly instead of GetDoubleArrayElements. I also ran performance metrics on both methods from the Java side via <code>System.currentTimeMillis()</code> and got the following performance times:</p>
  
  <p>GetDoubleArrayElements: 98 ms
  GetDirectBufferAddress: 96 ms</p>
  
  <p>Virtually no performance increase. Is there any reason this might be happening? I allocated the ByteBuffers on the Java side using <code>ByteBuffer.allocateDirect().order(ByteOrder.nativeOrder)</code> and <code>arrBuff.putDouble(arr[i])</code>. Am I missing something? Any reference material would be greatly appreciated, I'm just trying to learn.</p>