title: GPU Profiling and callbacks in OpenGL ES
body: <p>Is there a way to add callbacks in OpenGL ES similar to what DirectX has? I'm trying to profile the GPU performance, so I'm trying to figure out how long it took to execute certain parts of the GPU.</p>
  
  <p>Ideally, I "push" a marker/callback, then call a bunch of GL draw calls, then push another marker, and then find out how many milliseconds passed inbetween those two markers a frame later.</p>
  
  <p>(Any other ways to profile GPU performance would be helpful too.)</p>