title: Performance of gpu delegate, nnapi of tensorflow lite are almost the same on android mobile
body: <p>I use following codes to change the delegate on my phone(G3226)</p>
  
  <pre><code>try {     
        if(delegateNum == 1){
          GpuDelegate delegate = new GpuDelegate();
          Interpreter.Options options = (new Interpreter.Options()).addDelegate(delegate);
          d.tfLite = new Interpreter(loadModelFile(assetManager, modelFilename), options);
        }else if(delegateNum == 2){
          NnApiDelegate delegate = new NnApiDelegate();
          Interpreter.Options options = (new Interpreter.Options()).addDelegate(delegate);
          d.tfLite = new Interpreter(loadModelFile(assetManager, modelFilename), options);
        }else{
          d.tfLite = new Interpreter(loadModelFile(assetManager, modelFilename));
        }      
  
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
  </code></pre>
  
  <p>But the performance are almost the same, not sure what happens.</p>
  
  <ul>
  <li>Phone G3226</li>
  <li><p>TFLite versions    </p>
  
  <p>implementation 'org.tensorflow:tensorflow-lite:0.0.0-nightly'
  implementation 'org.tensorflow:tensorflow-lite-gpu:0.0.0-nightly'
  implementation 'org.tensorflow:tensorflow-lite-support:0.0.0-nightly'</p></li>
  <li><a href="http://storage.googleapis.com/download.tensorflow.org/models/tflite/coco_ssd_mobilenet_v1_1.0_quant_2018_06_29.zip" rel="nofollow noreferrer">Model link</a>, it is  a quantized SSD model for object detection(accuracy is not that good)</li>
  </ul>
  
  <p>Possible reasons I guess:</p>
  
  <ol>
  <li>This model is too small, not complicated enough for gpu or nnapi to show off</li>
  <li>gpu or nnapi on my phone are wek</li>
  <li>my phone do not support gpu or nnapi, so they drop back to cpu</li>
  </ol>
  
  <p>If it is 3, how could I check my phone support gpu or nnapi or not?Thanks</p>