change bf16 default to false

configs/fsdp.py

@@ -13,7 +13,7 @@ class fsdp_config:
     sharding_strategy: ShardingStrategy = ShardingStrategy.FULL_SHARD
     checkpoint_type: StateDictType = StateDictType.SHARDED_STATE_DICT  # alternatively can use SHARDED_STATE_DICT save one file per rank, and can resize the world-size.
     fsdp_activation_checkpointing: bool=True
-    pure_bf16: bool = True
+    pure_bf16: bool = False
     optimizer: str= "AdamW"