fix when lambda_distill is None in ofa (#550)

* fix

* fix when lambda is None

paddleslim/nas/ofa/ofa.py

@@ -324,7 +324,9 @@ class OFA(OFABase):
             else:
                 loss = distill_fn(Sact, Tact.detach())
             losses.append(loss)
-        return sum(losses) * self.distill_config.lambda_distill
+        if self.distill_config.lambda_distill != None:
+            return sum(losses) * self.distill_config.lambda_distill
+        return sum(losses)
 
     ### TODO: complete it
     def search(self, eval_func, condition):

tests/test_ofa.py

@@ -330,7 +330,6 @@ class TestOFACase2(TestOFA):
         }
         self.run_config = RunConfig(**default_run_config)
         default_distill_config = {
-            'lambda_distill': 0.01,
             'teacher_model': self.teacher_model,
             'mapping_layers': ['models.3.fn'],
         }