[SD 3.5 Dreambooth LoRA] support configurable training block & layers

examples/dreambooth/README_sd3.md

@@ -147,6 +147,40 @@ accelerate launch train_dreambooth_lora_sd3.py \
   --push_to_hub
 ```
 
+### Targeting Specific Blocks & Layers
+As image generation models get bigger & more powerful, more fine-tuners come to find that training only part of the 
+transformer blocks (sometimes as little as two) can be enough to get great results. 
+In some cases, it can be even better to maintain some of the blocks/layers frozen.
+
+For **SD3.5-Large** specifically, you may find this information useful (taken from: [Stable Diffusion 3.5 Large Fine-tuning Tutorial](https://stabilityai.notion.site/Stable-Diffusion-3-5-Large-Fine-tuning-Tutorial-11a61cdcd1968027a15bdbd7c40be8c6#12461cdcd19680788a23c650dab26b93):
+> [!NOTE]
+> A commonly believed heuristic that we verified once again during the construction of the SD3.5 family of models is that later/higher layers (i.e. `30 - 37`)* impact tertiary details more heavily. Conversely, earlier layers (i.e. `12 - 24` )* influence the overall composition/primary form more. 
+> So, freezing other layers/targeting specific layers is a viable approach.
+> `*`These suggested layers are speculative and not 100% guaranteed. The tips here are more or less a general idea for next steps.
+> **Photorealism**
+> In preliminary testing, we observed that freezing the last few layers of the architecture significantly improved model training when using a photorealistic dataset, preventing detail degradation introduced by small dataset from happening.
+> **Anatomy preservation**
+> To dampen any possible degradation of anatomy, training only the attention layers and **not** the adaptive linear layers could help. For reference, below is one of the transformer blocks.
+
+
+We've added `--lora_layers` and `--lora_blocks` to make LoRA training modules configurable. 
+- with `--lora_blocks` you can specify the block numbers for training. E.g. passing - 
+```diff
+--lora_blocks "12,13,14,15,16,17,18,19,20,21,22,23,24,30,31,32,33,34,35,36,37"
+```
+will trigger LoRA training of transformer blocks 12-24 and 30-37. By default, all blocks are trained. 
+- with `--lora_layers` you can specify the types of layers you wish to train. 
+By default, the trained layers are -  
+`attn.add_k_proj,attn.add_q_proj,attn.add_v_proj,attn.to_add_out,attn.to_k,attn.to_out.0,attn.to_q,attn.to_v`
+If you wish to have a leaner LoRA / train more blocks over layers you could pass - 
+```diff
+--lora_layers attn.to_k,attn.to_q,attn.to_v,attn.to_out.0
+```
+This will reduce LoRA size by roughly 50% for the same rank compared to the default. 
+However, if you're after compact LoRAs, it's our impression that maintaining the default setting for `--lora_layers` and
+freezing some of the early & blocks is usually better. 
+
+
 ### Text Encoder Training
 Alongside the transformer, LoRA fine-tuning of the CLIP text encoders is now also supported.
 To do so, just specify `--train_text_encoder` while launching training. Please keep the following points in mind:

examples/dreambooth/test_dreambooth_lora_sd3.py

@@ -136,6 +136,76 @@ def test_dreambooth_lora_latent_caching(self):
             starts_with_transformer = all(key.startswith("transformer") for key in lora_state_dict.keys())
             self.assertTrue(starts_with_transformer)
 
+    def test_dreambooth_lora_block(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            test_args = f"""
+                {self.script_path}
+                --pretrained_model_name_or_path {self.pretrained_model_name_or_path}
+                --instance_data_dir {self.instance_data_dir}
+                --instance_prompt {self.instance_prompt}
+                --resolution 64
+                --train_batch_size 1
+                --gradient_accumulation_steps 1
+                --max_train_steps 2
+                --lora_blocks 0
+                --learning_rate 5.0e-04
+                --scale_lr
+                --lr_scheduler constant
+                --lr_warmup_steps 0
+                --output_dir {tmpdir}
+                """.split()
+
+            run_command(self._launch_args + test_args)
+            # save_pretrained smoke test
+            self.assertTrue(os.path.isfile(os.path.join(tmpdir, "pytorch_lora_weights.safetensors")))
+
+            # make sure the state_dict has the correct naming in the parameters.
+            lora_state_dict = safetensors.torch.load_file(os.path.join(tmpdir, "pytorch_lora_weights.safetensors"))
+            is_lora = all("lora" in k for k in lora_state_dict.keys())
+            self.assertTrue(is_lora)
+
+            # when not training the text encoder, all the parameters in the state dict should start
+            # with `"transformer"` in their names.
+            # In this test, only params of transformer block 0 should be in the state dict
+            starts_with_transformer = all(
+                key.startswith("transformer.transformer_blocks.0") for key in lora_state_dict.keys()
+            )
+            self.assertTrue(starts_with_transformer)
+
+    def test_dreambooth_lora_layer(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            test_args = f"""
+                {self.script_path}
+                --pretrained_model_name_or_path {self.pretrained_model_name_or_path}
+                --instance_data_dir {self.instance_data_dir}
+                --instance_prompt {self.instance_prompt}
+                --resolution 64
+                --train_batch_size 1
+                --gradient_accumulation_steps 1
+                --max_train_steps 2
+                --lora_layers attn.to_k
+                --learning_rate 5.0e-04
+                --scale_lr
+                --lr_scheduler constant
+                --lr_warmup_steps 0
+                --output_dir {tmpdir}
+                """.split()
+
+            run_command(self._launch_args + test_args)
+            # save_pretrained smoke test
+            self.assertTrue(os.path.isfile(os.path.join(tmpdir, "pytorch_lora_weights.safetensors")))
+
+            # make sure the state_dict has the correct naming in the parameters.
+            lora_state_dict = safetensors.torch.load_file(os.path.join(tmpdir, "pytorch_lora_weights.safetensors"))
+            is_lora = all("lora" in k for k in lora_state_dict.keys())
+            self.assertTrue(is_lora)
+
+            # when not training the text encoder, all the parameters in the state dict should start
+            # with `"transformer"` in their names.
+            # In this test, only params of transformer block 0 should be in the state dict
+            starts_with_transformer = all("attn.to_k" in key for key in lora_state_dict.keys())
+            self.assertTrue(starts_with_transformer)
+
     def test_dreambooth_lora_sd3_checkpointing_checkpoints_total_limit(self):
         with tempfile.TemporaryDirectory() as tmpdir:
             test_args = f"""

examples/dreambooth/train_dreambooth_lora_sd3.py

@@ -571,6 +571,25 @@ def parse_args(input_args=None):
         "--adam_weight_decay_text_encoder", type=float, default=1e-03, help="Weight decay to use for text_encoder"
     )
 
+    parser.add_argument(
+        "--lora_layers",
+        type=str,
+        default=None,
+        help=(
+            "The transformer block layers to apply LoRA training on. Please specify the layers in a comma seperated string."
+            "For examples refer to https://github.com/huggingface/diffusers/blob/main/examples/dreambooth/README_SD3.md"
+        ),
+    )
+    parser.add_argument(
+        "--lora_blocks",
+        type=str,
+        default=None,
+        help=(
+            "The transformer blocks to apply LoRA training on. Please specify the block numbers in a comma seperated manner."
+            'E.g. - "--lora_blocks 12,30" will result in lora training of transformer blocks 12 and 30. For more examples refer to https://github.com/huggingface/diffusers/blob/main/examples/dreambooth/README_SD3.md'
+        ),
+    )
+
     parser.add_argument(
         "--adam_epsilon",
         type=float,
@@ -1222,13 +1241,31 @@ def main(args):
         if args.train_text_encoder:
             text_encoder_one.gradient_checkpointing_enable()
             text_encoder_two.gradient_checkpointing_enable()
+    if args.lora_layers is not None:
+        target_modules = [layer.strip() for layer in args.lora_layers.split(",")]
+    else:
+        target_modules = [
+            "attn.add_k_proj",
+            "attn.add_q_proj",
+            "attn.add_v_proj",
+            "attn.to_add_out",
+            "attn.to_k",
+            "attn.to_out.0",
+            "attn.to_q",
+            "attn.to_v",
+        ]
+    if args.lora_blocks is not None:
+        target_blocks = [int(block.strip()) for block in args.lora_blocks.split(",")]
+        target_modules = [
+            f"transformer_blocks.{block}.{module}" for block in target_blocks for module in target_modules
+        ]
 
     # now we will add new LoRA weights to the attention layers
     transformer_lora_config = LoraConfig(
         r=args.rank,
         lora_alpha=args.rank,
         init_lora_weights="gaussian",
-        target_modules=["to_k", "to_q", "to_v", "to_out.0"],
+        target_modules=target_modules,
     )
     transformer.add_adapter(transformer_lora_config)