disable amp by default on cpu

Author: haifeng-jin

benchmarks/torchbench_model.py

@@ -373,6 +373,9 @@ def is_accelerator_tpu(self):
     return self.benchmark_experiment.accelerator == "tpu"
 
   def use_amp(self):
+    # AMP is only supported on cuda and tpu, not on cpu.
+    if self.benchmark_experiment.accelerator == "cpu":
+      return False
     return self.is_training() or self.model_name in config(
     ).dtype.force_amp_for_fp16_bf16_models