title: what is XLA_GPU and XLA_CPU for tensorflow
body: <p>I can list gpu devices sing the following tensorflow code:</p>
  <pre><code>import tensorflow as tf
  from tensorflow.python.client import device_lib
  print(device_lib.list_local_devices())
  </code></pre>
  <p>The result is:</p>
  <pre><code>[name: &quot;/device:CPU:0&quot;
   device_type: &quot;CPU&quot;
   memory_limit: 268435456
   locality {
   }
   incarnation: 17897160860519880862, name: &quot;/device:XLA_GPU:0&quot;
   device_type: &quot;XLA_GPU&quot;
   memory_limit: 17179869184
   locality {
   }
   incarnation: 9751861134541508701
   physical_device_desc: &quot;device: XLA_GPU device&quot;, name: &quot;/device:XLA_CPU:0&quot;
   device_type: &quot;XLA_CPU&quot;
   memory_limit: 17179869184
   locality {
   }
   incarnation: 5368380567397471193
   physical_device_desc: &quot;device: XLA_CPU device&quot;, name: &quot;/device:GPU:0&quot;
   device_type: &quot;GPU&quot;
   memory_limit: 21366299034
   locality {
     bus_id: 1
     links {
       link {
         device_id: 1
         type: &quot;StreamExecutor&quot;
         strength: 1
       }
     }
   }
   incarnation: 7110958745101815531
   physical_device_desc: &quot;device: 0, name: Tesla P40, pci bus id: 0000:02:00.0, compute capability: 6.1&quot;, name: &quot;/device:GPU:1&quot;
   device_type: &quot;GPU&quot;
   memory_limit: 17336821351
   locality {
     bus_id: 1
     links {
       link {
         type: &quot;StreamExecutor&quot;
         strength: 1
       }
     }
   }
   incarnation: 3366465227705362600
   physical_device_desc: &quot;device: 1, name: Tesla P40, pci bus id: 0000:03:00.0, compute capability: 6.1&quot;, name: &quot;/device:GPU:2&quot;
   device_type: &quot;GPU&quot;
   memory_limit: 22590563943
   locality {
     bus_id: 2
     numa_node: 1
     links {
       link {
         device_id: 3
         type: &quot;StreamExecutor&quot;
         strength: 1
       }
     }
   }
   incarnation: 8774017944003495680
   physical_device_desc: &quot;device: 2, name: Tesla P40, pci bus id: 0000:83:00.0, compute capability: 6.1&quot;, name: &quot;/device:GPU:3&quot;
   device_type: &quot;GPU&quot;
   memory_limit: 22590563943
   locality {
     bus_id: 2
     numa_node: 1
     links {
       link {
         device_id: 2
         type: &quot;StreamExecutor&quot;
         strength: 1
       }
     }
   }
   incarnation: 2007348906807258050
   physical_device_desc: &quot;device: 3, name: Tesla P40, pci bus id: 0000:84:00.0, compute capability: 6.1&quot;]
  </code></pre>
  <p>I want to know what is <code>XLA_GPU</code> and <code>XLA_CPU</code>?</p>