keep model_avg on cpu

egs/librispeech/ASR/pruned_transducer_stateless4/train.py

@@ -867,10 +867,6 @@ def run(rank, world_size, args):
         model = DDP(model, device_ids=[rank])
     model.device = device
 
-    if rank == 0:
-        model_avg.to(device)
-        model_avg.device = device
-
     optimizer = Eve(model.parameters(), lr=params.initial_lr)
 
     scheduler = Eden(optimizer, params.lr_batches, params.lr_epochs)

icefall/checkpoint.py

@@ -467,5 +467,7 @@ def average_state_dict(
     uniqued_names = list(uniqued.values())
     for k in uniqued_names:
         state_dict_1[k] *= weight_1
-        state_dict_1[k] += state_dict_2[k] * weight_2
+        state_dict_1[k] += (
+            state_dict_2[k].to(device=state_dict_1[k].device) * weight_2
+        )
         state_dict_1[k] *= scaling_factor