Refactor: Move PEFT config from training script to policy level (#2806)

* move peft config from `lerobot_train` to policy level

* Update src/lerobot/scripts/lerobot_train.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Michel Aractingi <michel.aractingi@huggingface.co>

* copilot response

* Change the polciy function to return targets rather than peft config.`_get_default_peft_targets()` override in PI0, PI0.5, SmolVLA

* remove none check when building config dict

---------

Signed-off-by: Michel Aractingi <michel.aractingi@huggingface.co>
This commit is contained in:
Michel Aractingi
2026-01-16 17:14:28 +01:00
committed by GitHub
parent 112b2d173a
commit 19dce78457
5 changed files with 211 additions and 87 deletions
+11
View File
@@ -1297,3 +1297,14 @@ class PI0Policy(PreTrainedPolicy):
loss = losses.mean()
loss_dict["loss"] = loss.item()
return loss, loss_dict
def _get_default_peft_targets(self) -> dict[str, any]:
"""Return default PEFT target modules for PI0 fine-tuning."""
common_projections = (
"state_proj|action_in_proj|action_out_proj|action_time_mlp_in|action_time_mlp_out"
)
target_modules = rf"(.*\.gemma_expert\..*\.self_attn\.(q|v)_proj|model\.({common_projections}))"
return {
"target_modules": target_modules,
"modules_to_save": [],
}
@@ -1270,3 +1270,14 @@ class PI05Policy(PreTrainedPolicy):
loss = losses.mean()
loss_dict["loss"] = loss.item()
return loss, loss_dict
def _get_default_peft_targets(self) -> dict[str, any]:
"""Return default PEFT target modules for PI0.5 fine-tuning."""
common_projections = (
"state_proj|action_in_proj|action_out_proj|action_time_mlp_in|action_time_mlp_out"
)
target_modules = rf"(.*\.gemma_expert\..*\.self_attn\.(q|v)_proj|model\.({common_projections}))"
return {
"target_modules": target_modules,
"modules_to_save": [],
}
+164
View File
@@ -13,6 +13,7 @@
# limitations under the License.
import abc
import builtins
import dataclasses
import logging
import os
from importlib.resources import files
@@ -265,3 +266,166 @@ class PreTrainedPolicy(nn.Module, HubMixin, abc.ABC):
card = ModelCard.from_template(card_data, template_str=template_card)
card.validate()
return card
def wrap_with_peft(
self,
peft_config=None,
peft_cli_overrides: dict | None = None,
) -> "PreTrainedPolicy":
"""
Wrap this policy with PEFT adapters for parameter-efficient fine-tuning.
This method is the single entry point for PEFT integration. Subclasses should
override `_get_default_peft_targets()` to provide default target modules, and
`_validate_peft_config()` for policy-specific validation.
Args:
peft_config: Optional PEFT adapter configuration (e.g., LoraConfig).
If provided, used directly (with CLI overrides applied).
peft_cli_overrides: Optional dict of CLI overrides (method_type, target_modules, r, etc.)
These are merged with policy defaults to build the final config.
"""
from peft import get_peft_model
# If user provided a complete config, use it directly (with overrides)
if peft_config is not None:
final_config = peft_config
if peft_cli_overrides:
final_config = self._apply_peft_cli_overrides(final_config, peft_cli_overrides)
else:
# Build config from defaults + CLI overrides
final_config = self._build_peft_config(peft_cli_overrides or {})
# Validate the configuration
self._validate_peft_config(final_config)
# Freeze base parameters, only adapter params will be trained
for p in self.parameters():
p.requires_grad_(False)
# Store pretrained path for PEFT's base_model_name_or_path
if self.config.pretrained_path:
self.name_or_path = str(self.config.pretrained_path)
# Wrap with PEFT
peft_model = get_peft_model(self, final_config)
# Mark config as using PEFT for proper loading later
peft_model.config.use_peft = True
logging.info(f"Wrapped {self.name} with PEFT ({type(final_config).__name__})")
return peft_model
def _get_default_peft_targets(self) -> dict[str, any] | None:
"""
Return default PEFT target modules for this policy.
Override this in subclasses to provide policy-specific defaults. These defaults
are PEFT-method agnostic - they only specify which modules to target.
"""
return None
def _validate_peft_config(self, peft_config) -> None:
"""
Validate the PEFT configuration for this policy.
Override this in subclasses to add policy-specific validation or warnings.
The default implementation checks that a pretrained_path exists.
Args:
peft_config: The PEFT configuration to validate.
Raises:
ValueError: If the configuration is invalid.
"""
if not self.config.pretrained_path:
raise ValueError(
"Training from scratch using PEFT is unlikely to yield good results. "
"Supply a `policy.pretrained_path` to fine-tune an existing model."
)
def _preprocess_peft_cli_overrides(self, cli_overrides: dict, peft_method_type) -> dict:
"""
Preprocess CLI overrides: rename keys and handle method-specific init_type.
Args:
cli_overrides: Dict of CLI options (will be copied, not mutated).
peft_method_type: The PeftType enum value for the PEFT method.
Returns:
Preprocessed dict with renamed keys and init_type mapped to method-specific key.
"""
from peft import PeftType
cli_overrides = cli_overrides.copy()
# Handle the full_training_modules -> modules_to_save rename
if "full_training_modules" in cli_overrides:
cli_overrides["modules_to_save"] = cli_overrides.pop("full_training_modules")
# Remove method_type as it's handled separately
cli_overrides.pop("method_type", None)
# Handle init_type specially based on PEFT method
init_type = cli_overrides.pop("init_type", None)
if init_type is not None:
if peft_method_type == PeftType.LORA:
cli_overrides["init_lora_weights"] = init_type
elif peft_method_type == PeftType.MISS:
cli_overrides["init_weights"] = init_type
else:
raise ValueError(f"Init type '{init_type}' unknown for PEFT method {peft_method_type}.")
return cli_overrides
def _build_peft_config(self, cli_overrides: dict):
"""Build a PEFT config from policy defaults and CLI overrides."""
from peft import PEFT_TYPE_TO_CONFIG_MAPPING, PeftType
# Determine PEFT method type (default to LORA)
method_type_str = cli_overrides.get("method_type") or "lora"
peft_method_type = PeftType[method_type_str.upper()]
peft_config_cls = PEFT_TYPE_TO_CONFIG_MAPPING[peft_method_type]
# Preprocess CLI overrides
cli_overrides = self._preprocess_peft_cli_overrides(cli_overrides, peft_method_type)
# Start with policy defaults, apply CLI overrides
config_dict = dict(self._get_default_peft_targets() or {})
for key, value in cli_overrides.items():
if value is not None:
config_dict[key] = value
# Ensure we have target_modules
if not config_dict.get("target_modules"):
raise ValueError(
f"Policy '{self.name}' does not define default target_modules. "
"Please pass --peft.target_modules explicitly."
)
return peft_config_cls(**config_dict)
def _apply_peft_cli_overrides(self, peft_config, cli_overrides: dict):
"""Apply CLI overrides to an existing PEFT config."""
from peft import PEFT_TYPE_TO_CONFIG_MAPPING, PeftType
# Get method type from existing config or CLI override
method_type_str = cli_overrides.get("method_type")
if method_type_str:
peft_method_type = PeftType[method_type_str.upper()]
peft_config_cls = PEFT_TYPE_TO_CONFIG_MAPPING[peft_method_type]
else:
peft_method_type = PeftType(peft_config.peft_type)
peft_config_cls = type(peft_config)
# Preprocess CLI overrides
cli_overrides = self._preprocess_peft_cli_overrides(cli_overrides, peft_method_type)
# Start with existing config, apply CLI overrides
config_dict = {k: v for k, v in dataclasses.asdict(peft_config).items() if not k.startswith("_")}
for key, value in cli_overrides.items():
if value is not None:
config_dict[key] = value
return peft_config_cls(**config_dict)
@@ -480,6 +480,28 @@ class SmolVLAPolicy(PreTrainedPolicy):
actions = pad_vector(batch[ACTION], self.config.max_action_dim)
return actions
def _get_default_peft_targets(self) -> dict[str, any]:
"""Return default PEFT target modules for SmolVLA fine-tuning."""
common_projections = (
"state_proj|action_in_proj|action_out_proj|action_time_mlp_in|action_time_mlp_out"
)
target_modules = rf"(model\.vlm_with_expert\.lm_expert\..*\.(q|v)_proj|model\.({common_projections}))"
return {
"target_modules": target_modules,
"modules_to_save": [],
}
def _validate_peft_config(self, peft_config) -> None:
"""Validate PEFT configuration for SmolVLA."""
super()._validate_peft_config(peft_config)
if not self.config.load_vlm_weights:
import logging
logging.warning(
"Training SmolVLA from scratch using PEFT. This is unlikely to yield good results. "
"Set `load_vlm_weights=True` to fine-tune the existing policy."
)
def pad_tensor(tensor, max_len, pad_value=0):
"""
+3 -87
View File
@@ -148,92 +148,6 @@ def update_policy(
return train_metrics, output_dict
def get_default_peft_configuration(policy_type):
"""Build a basic PEFT configuration for the given policy type assuming that we train a policy from a checkpoint."""
common_projections = "state_proj|action_in_proj|action_out_proj|action_time_mlp_in|action_time_mlp_out"
if policy_type == "smolvla":
return {
"target_modules": rf"(model\.vlm_with_expert\.lm_expert\..*\.(q|v)_proj|model\.({common_projections}))",
"modules_to_save": [],
}
elif policy_type in ("pi0", "pi05"):
return {
"target_modules": rf"(.*\.gemma_expert\..*\.self_attn.(q|v)_proj|model\.({common_projections}))",
"modules_to_save": [],
}
return {"modules_to_save": None}
def wrap_policy_in_peft_model(cfg, policy):
from peft import PEFT_TYPE_TO_CONFIG_MAPPING, PeftType, get_peft_model
# Disable all gradients because we'll only train the parameters selected by the PEFT method.
# Layers that should receive gradients anyway need to be listed in `modules_to_save`.
for p in policy.parameters():
p.requires_grad_(False)
if not cfg.policy.pretrained_path:
raise ValueError(
"Training from scratch using PEFT. This is unlikely to yield good results. "
"Supply a `policy.path` to fine-tune an existing model."
)
if cfg.policy.type == "smolvla" and not cfg.policy.load_vlm_weights:
logging.warning(
"Training SmolVLA from scratch using PEFT. This is unlikely to yield good results. Set "
"`load_vlm_weights=True` to fine-tune the existing policy."
)
peft_config_policy = get_default_peft_configuration(cfg.policy.type)
peft_config_cli = dataclasses.asdict(cfg.peft) if cfg.peft else {}
peft_config_cli["modules_to_save"] = peft_config_cli["full_training_modules"] # compatibility with PEFT
peft_method_type = PeftType[peft_config_cli["method_type"].upper()]
peft_config_cls = PEFT_TYPE_TO_CONFIG_MAPPING[peft_method_type]
# Handle specific CLI overrides
for key in ["target_modules", "modules_to_save", "r"]:
if peft_config_cli[key] is not None:
peft_config_policy[key] = peft_config_cli[key]
if "target_modules" not in peft_config_policy:
raise ValueError(
f"There is no default `target_modules` value for policy {cfg.policy.type}. Please pass it manually."
)
# Init method depends on the used PEFT method, your specific PEFT method
# might not be considered here, in that case an error is raised.
if peft_config_cli["init_type"] is not None:
if peft_method_type == "LORA":
peft_config_policy["init_lora_weights"] = peft_config_cli["init_type"]
elif peft_method_type == "MISS":
peft_config_policy["init_weights"] = peft_config_cli["init_type"]
else:
raise ValueError(
f"Init type {peft_config_cli['init_type']} unknown for PEFT method {peft_method_type}."
)
# PEFT uses this attribute to set adapter_config.base_name_or_path which we use for loading the
# correct base model in `make_policy` since in a PEFT loading setting we only get the path to the
# adapter, not the base model.
if policy.config.pretrained_path:
policy.name_or_path = str(policy.config.pretrained_path)
# Finally wrap the policy in a PEFT model
policy = get_peft_model(
policy,
peft_config_cls(**peft_config_policy),
)
# Make sure that the config is tagged as using PEFT so that the loading code can take the
# appropriate steps to use the adapter weights and the PEFT config instead of the full model weights.
policy.config.use_peft = True
return policy
@parser.wrap()
def train(cfg: TrainPipelineConfig, accelerator: Accelerator | None = None):
"""
@@ -326,7 +240,9 @@ def train(cfg: TrainPipelineConfig, accelerator: Accelerator | None = None):
if cfg.peft is not None:
logging.info("Using PEFT! Wrapping model.")
policy = wrap_policy_in_peft_model(cfg, policy)
# Convert CLI peft config to dict for overrides
peft_cli_overrides = dataclasses.asdict(cfg.peft)
policy = policy.wrap_with_peft(peft_cli_overrides=peft_cli_overrides)
# Wait for all processes to finish policy creation before continuing
accelerator.wait_for_everyone()