Merge pull request #791 from Isotr0py/dev

Intergrate fp16/bf16 support to sdxl model loading

library/sdxl_model_util.py

@@ -160,7 +160,7 @@ def _load_state_dict_on_device(model, state_dict, device, dtype=None):
 
 def load_models_from_sdxl_checkpoint(model_version, ckpt_path, map_location, dtype=None):
     # model_version is reserved for future use
-    # dtype is reserved for full_fp16/bf16 integration. Text Encoder will remain fp32, because it runs on CPU when caching
+    # dtype is used for full_fp16/bf16 integration. Text Encoder will remain fp32, because it runs on CPU when caching
 
     # Load the state dict
     if model_util.is_safetensors(ckpt_path):
@@ -193,7 +193,7 @@ def load_models_from_sdxl_checkpoint(model_version, ckpt_path, map_location, dty
     for k in list(state_dict.keys()):
         if k.startswith("model.diffusion_model."):
             unet_sd[k.replace("model.diffusion_model.", "")] = state_dict.pop(k)
-    info = _load_state_dict_on_device(unet, unet_sd, device=map_location)
+    info = _load_state_dict_on_device(unet, unet_sd, device=map_location, dtype=dtype)
     print("U-Net: ", info)
 
     # Text Encoders
@@ -221,7 +221,8 @@ def load_models_from_sdxl_checkpoint(model_version, ckpt_path, map_location, dty
         # torch_dtype="float32",
         # transformers_version="4.25.0.dev0",
     )
-    text_model1 = CLIPTextModel._from_config(text_model1_cfg)
+    with init_empty_weights():
+        text_model1 = CLIPTextModel._from_config(text_model1_cfg)
 
     # Text Encoder 2 is different from Stability AI's SDXL. SDXL uses open clip, but we use the model from HuggingFace.
     # Note: Tokenizer from HuggingFace is different from SDXL. We must use open clip's tokenizer.
@@ -246,7 +247,8 @@ def load_models_from_sdxl_checkpoint(model_version, ckpt_path, map_location, dty
         # torch_dtype="float32",
         # transformers_version="4.25.0.dev0",
     )
-    text_model2 = CLIPTextModelWithProjection(text_model2_cfg)
+    with init_empty_weights():
+        text_model2 = CLIPTextModelWithProjection(text_model2_cfg)
 
     print("loading text encoders from checkpoint")
     te1_sd = {}
@@ -257,21 +259,22 @@ def load_models_from_sdxl_checkpoint(model_version, ckpt_path, map_location, dty
         elif k.startswith("conditioner.embedders.1.model."):
             te2_sd[k] = state_dict.pop(k)
 
-    info1 = text_model1.load_state_dict(te1_sd)
+    info1 = _load_state_dict_on_device(text_model1, te1_sd, device=map_location)    # remain fp32
     print("text encoder 1:", info1)
 
     converted_sd, logit_scale = convert_sdxl_text_encoder_2_checkpoint(te2_sd, max_length=77)
-    info2 = text_model2.load_state_dict(converted_sd)
+    info2 = _load_state_dict_on_device(text_model2, converted_sd, device=map_location)  # remain fp32
     print("text encoder 2:", info2)
 
     # prepare vae
     print("building VAE")
     vae_config = model_util.create_vae_diffusers_config()
-    vae = AutoencoderKL(**vae_config)  # .to(device)
+    with init_empty_weights():
+        vae = AutoencoderKL(**vae_config)
 
     print("loading VAE from checkpoint")
     converted_vae_checkpoint = model_util.convert_ldm_vae_checkpoint(state_dict, vae_config)
-    info = vae.load_state_dict(converted_vae_checkpoint)
+    info = _load_state_dict_on_device(vae, converted_vae_checkpoint, device=map_location, dtype=dtype)
     print("VAE:", info)
 
     ckpt_info = (epoch, global_step) if epoch is not None else None

library/sdxl_train_util.py

@@ -18,6 +18,7 @@ TOKENIZER2_PATH = "laion/CLIP-ViT-bigG-14-laion2B-39B-b160k"
 
 def load_target_model(args, accelerator, model_version: str, weight_dtype):
     # load models for each process
+    model_dtype = match_mixed_precision(args, weight_dtype)  # prepare fp16/bf16
     for pi in range(accelerator.state.num_processes):
         if pi == accelerator.state.local_process_index:
             print(f"loading model for process {accelerator.state.local_process_index}/{accelerator.state.num_processes}")
@@ -36,6 +37,7 @@ def load_target_model(args, accelerator, model_version: str, weight_dtype):
                 model_version,
                 weight_dtype,
                 accelerator.device if args.lowram else "cpu",
+                model_dtype
             )
 
             # work on low-ram device
@@ -54,7 +56,8 @@ def load_target_model(args, accelerator, model_version: str, weight_dtype):
     return load_stable_diffusion_format, text_encoder1, text_encoder2, vae, unet, logit_scale, ckpt_info
 
 
-def _load_target_model(name_or_path: str, vae_path: Optional[str], model_version: str, weight_dtype, device="cpu"):
+def _load_target_model(name_or_path: str, vae_path: Optional[str], model_version: str, weight_dtype, device="cpu", model_dtype=None):
+    # model_dtype only work with full fp16/bf16
     name_or_path = os.readlink(name_or_path) if os.path.islink(name_or_path) else name_or_path
     load_stable_diffusion_format = os.path.isfile(name_or_path)  # determine SD or Diffusers
 
@@ -67,7 +70,7 @@ def _load_target_model(name_or_path: str, vae_path: Optional[str], model_version
             unet,
             logit_scale,
             ckpt_info,
-        ) = sdxl_model_util.load_models_from_sdxl_checkpoint(model_version, name_or_path, device, weight_dtype)
+        ) = sdxl_model_util.load_models_from_sdxl_checkpoint(model_version, name_or_path, device, model_dtype)
     else:
         # Diffusers model is loaded to CPU
         from diffusers import StableDiffusionXLPipeline
@@ -77,7 +80,7 @@ def _load_target_model(name_or_path: str, vae_path: Optional[str], model_version
         try:
             try:
                 pipe = StableDiffusionXLPipeline.from_pretrained(
-                    name_or_path, torch_dtype=weight_dtype, variant=variant, tokenizer=None
+                    name_or_path, torch_dtype=model_dtype, variant=variant, tokenizer=None
                 )
             except EnvironmentError as ex:
                 if variant is not None:
@@ -93,6 +96,13 @@ def _load_target_model(name_or_path: str, vae_path: Optional[str], model_version
 
         text_encoder1 = pipe.text_encoder
         text_encoder2 = pipe.text_encoder_2
+
+        # convert to fp32 for cache text_encoders outputs
+        if text_encoder1.dtype != torch.float32:
+            text_encoder1 = text_encoder1.to(dtype=torch.float32)
+        if text_encoder2.dtype != torch.float32:
+            text_encoder2 = text_encoder2.to(dtype=torch.float32)
+
         vae = pipe.vae
         unet = pipe.unet
         del pipe
@@ -101,7 +111,7 @@ def _load_target_model(name_or_path: str, vae_path: Optional[str], model_version
         state_dict = sdxl_model_util.convert_diffusers_unet_state_dict_to_sdxl(unet.state_dict())
         with init_empty_weights():
             unet = sdxl_original_unet.SdxlUNet2DConditionModel()  # overwrite unet
-        sdxl_model_util._load_state_dict_on_device(unet, state_dict, device=device)
+        sdxl_model_util._load_state_dict_on_device(unet, state_dict, device=device, dtype=model_dtype)
         print("U-Net converted to original U-Net")
 
         logit_scale = None
@@ -146,6 +156,21 @@ def load_tokenizers(args: argparse.Namespace):
     return tokeniers
 
 
+def match_mixed_precision(args, weight_dtype):
+    if args.full_fp16:
+        assert (
+            weight_dtype == torch.float16
+        ), "full_fp16 requires mixed precision='fp16' / full_fp16を使う場合はmixed_precision='fp16'を指定してください。"
+        return weight_dtype
+    elif args.full_bf16:
+        assert (
+            weight_dtype == torch.bfloat16
+        ), "full_bf16 requires mixed precision='bf16' / full_bf16を使う場合はmixed_precision='bf16'を指定してください。"
+        return weight_dtype
+    else:
+        return None
+
+
 def timestep_embedding(timesteps, dim, max_period=10000):
     """
     Create sinusoidal timestep embeddings.