Raise ValueError instead of asserts in src/transformers/benchmark/benchmark.py (#13951)

* Raise ValueError exception instead of assert

* Remove f unnecessary f-strings

* Remove unused f-strings

src/transformers/benchmark/benchmark.py

@@ -111,7 +111,8 @@ class PyTorchBenchmark(Benchmark):
 
         if self.args.fp16:
             logger.info("Running training in Mixed Precision...")
-            assert self.args.is_gpu, "Mixed precision is possible only for GPU."
+            if not self.args.is_gpu:
+                raise ValueError("Mixed precision is possible only for GPU.")
             # amp seems to have memory leaks so that memory usage
             # is measured using .half() for now https://github.com/NVIDIA/apex/issues/439
             model.half()
@@ -170,7 +171,8 @@ class PyTorchBenchmark(Benchmark):
 
         if self.args.fp16:
             logger.info("Running training in Mixed Precision...")
-            assert self.args.is_gpu, "Mixed precision is possible only for GPU."
+            if not self.args.is_gpu:
+                raise ValueError("Mixed precision is possible only for GPU.")
 
             # amp seems to have memory leaks so that memory usage
             # is measured using .half() for now https://github.com/NVIDIA/apex/issues/439