class ModelHook: """ A hook that contains callbacks to be executed just before and after the forward method of a model. The difference with PyTorch existing hooks is that they get passed along the kwargs. Class attribute: - **no_grad** (`bool`, *optional*, defaults to `False`) -- Whether or not to execute the actual forward pass under the `torch.no_grad()` context manager. """ no_grad = False def init_hook(self, module): """ To be executed when the hook is attached to the module. Args: module (`torch.nn.Module`): The module attached to this hook. """ return module def pre_forward(self, module, *args, **kwargs): """ To be executed just before the forward method of the model. Args: module (`torch.nn.Module`): The module whose forward pass will be executed just after this event. args (`Tuple[Any]`): The positional arguments passed to the module. kwargs (`Dict[Str, Any]`): The keyword arguments passed to the module. Returns: `Tuple[Tuple[Any], Dict[Str, Any]]`: A tuple with the treated `args` and `kwargs`. """ return args, kwargs def post_forward(self, module, output): """ To be executed just after the forward method of the model. Args: module (`torch.nn.Module`): The module whose forward pass been executed just before this event. output (`Any`): The output of the module. Returns: `Any`: The processed `output`. """ return output def detach_hook(self, module): """ To be executed when the hook is detached from a module. Args: module (`torch.nn.Module`): The module detached from this hook. """ return module class SequentialHook(ModelHook): """ A hook that can contain several hooks and iterates through them at each event. """ def __init__(self, *hooks): self.hooks = hooks def init_hook(self, module): for hook in self.hooks: module = hook.init_hook(module) return module def pre_forward(self, module, *args, **kwargs): for hook in self.hooks: args, kwargs = hook.pre_forward(module, *args, **kwargs) return args, kwargs def post_forward(self, module, output): for hook in self.hooks: output = hook.post_forward(module, output) return output def detach_hook(self, module): for hook in self.hooks: module = hook.detach_hook(module) return module def add_hook_to_module(module: nn.Module, hook: ModelHook, append: bool = False): """ Adds a hook to a given module. This will rewrite the `forward` method of the module to include the hook, to remove this behavior and restore the original `forward` method, use `remove_hook_from_module`. If the module already contains a hook, this will replace it with the new hook passed by default. To chain two hooks together, pass `append=True`, so it chains the current and new hook into an instance of the `SequentialHook` class. Args: module (`torch.nn.Module`): The module to attach a hook to. hook (`ModelHook`): The hook to attach. append (`bool`, *optional*, defaults to `False`): Whether the hook should be chained with an existing one (if module already contains a hook) or not. Returns: `torch.nn.Module`: The same module, with the hook attached (the module is modified in place, so the result can be discarded). """ if append and (getattr(module, "_hf_hook", None) is not None): old_hook = module._hf_hook remove_hook_from_module(module) hook = SequentialHook(old_hook, hook) if hasattr(module, "_hf_hook") and hasattr(module, "_old_forward"): # If we already put some hook on this module, we replace it with the new one. old_forward = module._old_forward else: old_forward = module.forward module._old_forward = old_forward module = hook.init_hook(module) module._hf_hook = hook def new_forward(module, *args, **kwargs): args, kwargs = module._hf_hook.pre_forward(module, *args, **kwargs) if module._hf_hook.no_grad: with torch.no_grad(): output = module._old_forward(*args, **kwargs) else: output = module._old_forward(*args, **kwargs) return module._hf_hook.post_forward(module, output) module.forward = functools.update_wrapper(functools.partial(new_forward, module), old_forward) return module def remove_hook_from_module(module: nn.Module, recurse=False): """ Removes any hook attached to a module via `add_hook_to_module`. Args: module (`torch.nn.Module`): The module to attach a hook to. recurse (`bool`, **optional**): Whether to remove the hooks recursively Returns: `torch.nn.Module`: The same module, with the hook detached (the module is modified in place, so the result can be discarded). """ if hasattr(module, "_hf_hook"): module._hf_hook.detach_hook(module) delattr(module, "_hf_hook") if hasattr(module, "_old_forward"): module.forward = module._old_forward delattr(module, "_old_forward") if recurse: for child in module.children(): remove_hook_from_module(child, recurse) return module class AlignDevicesHook(ModelHook): """ A generic `ModelHook` that ensures inputs and model weights are on the same device for the forward pass of the associated module, potentially offloading the weights after the forward pass. Args: execution_device (`torch.device`, *optional*): The device on which inputs and model weights should be placed before the forward pass. offload (`bool`, *optional*, defaults to `False`): Whether or not the weights should be offloaded after the forward pass. io_same_device (`bool`, *optional*, defaults to `False`): Whether or not the output should be placed on the same device as the input was. weights_map (`Mapping[str, torch.Tensor]`, *optional*): When the model weights are offloaded, a (potentially lazy) map from param names to the tensor values. offload_buffers (`bool`, *optional*, defaults to `False`): Whether or not to include the associated module's buffers when offloading. place_submodules (`bool`, *optional*, defaults to `False`): Whether to place the submodules on `execution_device` during the `init_hook` event. """ def __init__( self, execution_device: Optional[Union[int, str, torch.device]] = None, offload: bool = False, io_same_device: bool = False, weights_map: Optional[Mapping] = None, offload_buffers: bool = False, place_submodules: bool = False, skip_keys: Optional[Union[str, List[str]]] = None, ): self.execution_device = execution_device self.offload = offload self.io_same_device = io_same_device self.weights_map = weights_map self.offload_buffers = offload_buffers self.place_submodules = place_submodules self.skip_keys = skip_keys # Will contain the input device when `io_same_device=True`. self.input_device = None self.param_original_devices = {} self.buffer_original_devices = {} def __repr__(self): return ( f"AlignDevicesHook(execution_device={self.execution_device}, offload={self.offload}, " f"io_same_device={self.io_same_device}, offload_buffers={self.offload_buffers}, " f"place_submodules={self.place_submodules}, skip_keys={repr(self.skip_keys)})" ) def init_hook(self, module): if not self.offload and self.execution_device is not None: for name, _ in named_module_tensors(module, recurse=self.place_submodules): set_module_tensor_to_device(module, name, self.execution_device) elif self.offload: self.original_devices = { name: param.device for name, param in named_module_tensors(module, recurse=self.place_submodules) } if self.weights_map is None: self.weights_map = { name: param.to("cpu") for name, param in named_module_tensors( module, include_buffers=self.offload_buffers, recurse=self.place_submodules ) } for name, _ in named_module_tensors( module, include_buffers=self.offload_buffers, recurse=self.place_submodules, remove_non_persistent=True ): set_module_tensor_to_device(module, name, "meta") if not self.offload_buffers and self.execution_device is not None: for name, _ in module.named_buffers(recurse=self.place_submodules): set_module_tensor_to_device(module, name, self.execution_device) elif self.offload_buffers and self.execution_device is not None: for name in get_non_persistent_buffers(module, recurse=self.place_submodules): set_module_tensor_to_device(module, name, self.execution_device) return module def pre_forward(self, module, *args, **kwargs): if self.io_same_device: self.input_device = find_device([args, kwargs]) if self.offload: for name, _ in named_module_tensors( module, include_buffers=self.offload_buffers, recurse=self.place_submodules, remove_non_persistent=True, ): fp16_statistics = None if "weight" in name and name.replace("weight", "SCB") in self.weights_map.keys(): if self.weights_map[name].dtype == torch.int8: fp16_statistics = self.weights_map[name.replace("weight", "SCB")] set_module_tensor_to_device( module, name, self.execution_device, value=self.weights_map[name], fp16_statistics=fp16_statistics ) return send_to_device(args, self.execution_device), send_to_device( kwargs, self.execution_device, skip_keys=self.skip_keys ) def post_forward(self, module, output): if self.offload: for name, _ in named_module_tensors( module, include_buffers=self.offload_buffers, recurse=self.place_submodules, remove_non_persistent=True, ): set_module_tensor_to_device(module, name, "meta") if type(module).__name__ == "Linear8bitLt": module.state.SCB = None module.state.CxB = None if self.io_same_device and self.input_device is not None: output = send_to_device(output, self.input_device, skip_keys=self.skip_keys) return output def detach_hook(self, module): if self.offload: for name, device in self.original_devices.items(): if device != torch.device("meta"): set_module_tensor_to_device(module, name, device, value=self.weights_map.get(name, None)) return module def attach_execution_device_hook( module: torch.nn.Module, execution_device: Union[int, str, torch.device], skip_keys: Optional[Union[str, List[str]]] = None, preload_module_classes: Optional[List[str]] = None, ): """ Recursively attaches `AlignDevicesHook` to all submodules of a given model to make sure they have the right execution device Args: module (`torch.nn.Module`): The module where we want to attach the hooks. execution_device (`int`, `str` or `torch.device`): The device on which inputs and model weights should be placed before the forward pass. skip_keys (`str` or `List[str]`, *optional*): A list of keys to ignore when moving inputs or outputs between devices. preload_module_classes (`List[str]`, *optional*): A list of classes whose instances should load all their weights (even in the submodules) at the beginning of the forward. This should only be used for classes that have submodules which are registered but not called directly during the forward, for instance if a `dense` linear layer is registered, but at forward, `dense.weight` and `dense.bias` are used in some operations instead of calling `dense` directly. """ if not hasattr(module, "_hf_hook") and len(module.state_dict()) > 0: add_hook_to_module(module, AlignDevicesHook(execution_device, skip_keys=skip_keys)) # Break the recursion if we get to a preload module. if preload_module_classes is not None and module.__class__.__name__ in preload_module_classes: return for child in module.children(): attach_execution_device_hook(child, execution_device) def attach_align_device_hook( module: torch.nn.Module, execution_device: Optional[torch.device] = None, offload: bool = False, weights_map: Optional[Mapping] = None, offload_buffers: bool = False, module_name: str = "", skip_keys: Optional[Union[str, List[str]]] = None, preload_module_classes: Optional[List[str]] = None, ): """ Recursively attaches `AlignDevicesHook` to all submodules of a given model that have direct parameters and/or buffers. Args: module (`torch.nn.Module`): The module where we want to attach the hooks. execution_device (`torch.device`, *optional*): The device on which inputs and model weights should be placed before the forward pass. offload (`bool`, *optional*, defaults to `False`): Whether or not the weights should be offloaded after the forward pass. weights_map (`Mapping[str, torch.Tensor]`, *optional*): When the model weights are offloaded, a (potentially lazy) map from param names to the tensor values. offload_buffers (`bool`, *optional*, defaults to `False`): Whether or not to include the associated module's buffers when offloading. module_name (`str`, *optional*, defaults to `""`): The name of the module. skip_keys (`str` or `List[str]`, *optional*): A list of keys to ignore when moving inputs or outputs between devices. preload_module_classes (`List[str]`, *optional*): A list of classes whose instances should load all their weights (even in the submodules) at the beginning of the forward. This should only be used for classes that have submodules which are registered but not called directly during the forward, for instance if a `dense` linear layer is registered, but at forward, `dense.weight` and `dense.bias` are used in some operations instead of calling `dense` directly. """ # Attach the hook on this module if it has any direct tensor. directs = named_module_tensors(module) full_offload = ( offload and preload_module_classes is not None and module.__class__.__name__ in preload_module_classes ) if len(list(directs)) > 0 or full_offload: if weights_map is not None: prefix = f"{module_name}." if len(module_name) > 0 else "" prefixed_weights_map = PrefixedDataset(weights_map, prefix) else: prefixed_weights_map = None hook = AlignDevicesHook( execution_device=execution_device, offload=offload, weights_map=prefixed_weights_map, offload_buffers=offload_buffers, place_submodules=full_offload, skip_keys=skip_keys, ) add_hook_to_module(module, hook, append=True) # We stop the recursion in case we hit the full offload. if full_offload: return # Recurse on all children of the module. for child_name, child in module.named_children(): child_name = f"{module_name}.{child_name}" if len(module_name) > 0 else child_name attach_align_device_hook( child, execution_device=execution_device, offload=offload, weights_map=weights_map, offload_buffers=offload_buffers, module_name=child_name, preload_module_classes=preload_module_classes, skip_keys=skip_keys, ) def remove_hook_from_submodules(module: nn.Module): """ Recursively removes all hooks attached on the submodules of a given model. Args: module (`torch.nn.Module`): The module on which to remove all hooks. """ remove_hook_from_module(module) for child in module.children(): remove_hook_from_submodules(child) def attach_align_device_hook_on_blocks( module: nn.Module, execution_device: Optional[Union[torch.device, Dict[str, torch.device]]] = None, offload: Union[bool, Dict[str, bool]] = False, weights_map: Mapping = None, offload_buffers: bool = False, module_name: str = "", skip_keys: Optional[Union[str, List[str]]] = None, preload_module_classes: Optional[List[str]] = None, ): """ Attaches `AlignDevicesHook` to all blocks of a given model as needed. Args: module (`torch.nn.Module`): The module where we want to attach the hooks. execution_device (`torch.device` or `Dict[str, torch.device]`, *optional*): The device on which inputs and model weights should be placed before the forward pass. It can be one device for the whole module, or a dictionary mapping module name to device. offload (`bool`, *optional*, defaults to `False`): Whether or not the weights should be offloaded after the forward pass. It can be one boolean for the whole module, or a dictionary mapping module name to boolean. weights_map (`Mapping[str, torch.Tensor]`, *optional*): When the model weights are offloaded, a (potentially lazy) map from param names to the tensor values. offload_buffers (`bool`, *optional*, defaults to `False`): Whether or not to include the associated module's buffers when offloading. module_name (`str`, *optional*, defaults to `""`): The name of the module. skip_keys (`str` or `List[str]`, *optional*): A list of keys to ignore when moving inputs or outputs between devices. preload_module_classes (`List[str]`, *optional*): A list of classes whose instances should load all their weights (even in the submodules) at the beginning of the forward. This should only be used for classes that have submodules which are registered but not called directly during the forward, for instance if a `dense` linear layer is registered, but at forward, `dense.weight` and `dense.bias` are used in some operations instead of calling `dense` directly. """ # If one device and one offload, we've got one hook. if not isinstance(execution_device, Mapping) and not isinstance(offload, dict): if not offload: hook = AlignDevicesHook( execution_device=execution_device, io_same_device=True, skip_keys=skip_keys, place_submodules=True ) add_hook_to_module(module, hook) else: attach_align_device_hook( module, execution_device=execution_device, offload=True, weights_map=weights_map, offload_buffers=offload_buffers, module_name=module_name, skip_keys=skip_keys, ) return if not isinstance(execution_device, Mapping): execution_device = {key: execution_device for key in offload.keys()} if not isinstance(offload, Mapping): offload = {key: offload for key in execution_device.keys()} if module_name in execution_device and module_name in offload and not offload[module_name]: hook = AlignDevicesHook( execution_device=execution_device[module_name], offload_buffers=offload_buffers, io_same_device=(module_name == ""), place_submodules=True, skip_keys=skip_keys, ) add_hook_to_module(module, hook) attach_execution_device_hook(module, execution_device[module_name]) elif module_name in execution_device and module_name in offload: attach_align_device_hook( module, execution_device=execution_device[module_name], offload=True, weights_map=weights_map, offload_buffers=offload_buffers, module_name=module_name, skip_keys=skip_keys, preload_module_classes=preload_module_classes, ) if not hasattr(module, "_hf_hook"): hook = AlignDevicesHook( execution_device=execution_device[module_name], io_same_device=(module_name == ""), skip_keys=skip_keys ) add_hook_to_module(module, hook) attach_execution_device_hook( module, execution_device[module_name], preload_module_classes=preload_module_classes, skip_keys=skip_keys, ) elif module_name == "": hook = AlignDevicesHook(execution_device=execution_device.get(""), io_same_device=True, skip_keys=skip_keys) add_hook_to_module(module, hook) for child_name, child in module.named_children(): child_name = f"{module_name}.{child_name}" if len(module_name) > 0 else child_name attach_align_device_hook_on_blocks( child, execution_device=execution_device, offload=offload, weights_map=weights_map, offload_buffers=offload_buffers, module_name=child_name, preload_module_classes=preload_module_classes, skip_keys=skip_keys, ) class CpuOffload(ModelHook): """ Offloads a model on the CPU until its forward pass is called. The model will not be offloaded back to the CPU after the forward, the user needs to call the `init_hook` method again for this. Args: execution_device(`str`, `int` or `torch.device`, *optional*): The device on which the model should be executed. Will default to the MPS device if it's available, then GPU 0 if there is a GPU, and finally to the CPU. prev_module_hook (`UserCpuOffloadHook`, *optional*): The hook sent back by [`cpu_offload_with_hook`] for a previous model in the pipeline you are running. If passed, its offload method will be called just before the forward of the model to which this hook is attached. """ def __init__( self, execution_device: Optional[Union[str, int, torch.device]] = None, prev_module_hook: Optional["UserCpuOffloadHook"] = None, ): self.prev_module_hook = prev_module_hook self.execution_device = execution_device if execution_device is not None else PartialState().default_device def init_hook(self, module): return module.to("cpu") def pre_forward(self, module, *args, **kwargs): if self.prev_module_hook is not None: self.prev_module_hook.offload() module.to(self.execution_device) return send_to_device(args, self.execution_device), send_to_device(kwargs, self.execution_device) class UserCpuOffloadHook: """ A simple hook grouping a model and a `ModelHook`, which provides easy APIs for to call the init method of the hook or remove it entirely. """ def __init__(self, model, hook): self.model = model self.hook = hook def offload(self): self.hook.init_hook(self.model) def remove(self): remove_hook_from_module(self.model)