Prevent ZeroDivisionError on `trainer.evaluate` if model and dataset are tiny (#24049)

Prevent ZeroDivisionError if evaluation is too quick

src/transformers/trainer_utils.py

@@ -350,6 +350,8 @@ def speed_metrics(split, start_time, num_samples=None, num_steps=None):
     """
     runtime = time.time() - start_time
     result = {f"{split}_runtime": round(runtime, 4)}
+    if runtime == 0:
+        return result
     if num_samples is not None:
         samples_per_second = num_samples / runtime
         result[f"{split}_samples_per_second"] = round(samples_per_second, 3)