add logging and make sure model unloads to float16

scripts/finetune.py

@@ -176,6 +176,7 @@ def train(
     if "merge_lora" in kwargs and cfg.adapter is not None:
         logging.info("running merge of LoRA with base model")
         model = model.merge_and_unload()
+        model.to(dtype=torch.float16)
 
         if cfg.local_rank == 0:
             logging.info("saving merged model")

src/axolotl/utils/validation.py

@@ -1,3 +1,6 @@
+import logging
+
+
 def validate_config(cfg):
     if cfg.adapter == "qlora":
         if cfg.merge_lora:
@@ -9,6 +12,9 @@ def validate_config(cfg):
             assert cfg.load_in_8bit is False
             assert cfg.load_4bit is False
             assert cfg.load_in_4bit is True
+    if cfg.load_in_8bit and cfg.adapter == "lora":
+        logging.warning("we recommend setting `load_in_8bit: true`")
+
     # TODO
     # MPT 7b
     # https://github.com/facebookresearch/bitsandbytes/issues/25