title: How to check if keras tensorflow backend is GPU or CPU version?
body: <p>I understand that when installing tensorflow, you either install the GPU or CPU version. How can I check which one is installed (I use linux). </p>
  
  <p>If the GPU version is installed, would it be automatically running on CPU if GPU is unavailable or would it throw an error? And if GPU is available, is there a specific field or value you need to set to make sure it's running on GPU?</p>