import math import warnings from collections.abc import Sequence from functools import partial from typing import Optional, Tuple, Union import torch from torch import nn from .norm import NORM_CLASS_REGISTRY def torch_default_param_init_fn_(module: nn.Module, verbose: int=0, **kwargs): del kwargs if verbose > 1: warnings.warn(f"Initializing network using module's reset_parameters attribute") if hasattr(module, 'reset_parameters'): module.reset_parameters() def fused_init_helper_(module: nn.Module, init_fn_): _fused = getattr(module, '_fused', None) if _fused is None: raise RuntimeError(f'Internal logic error') (dim, splits) = _fused splits = (0, *splits, module.weight.size(dim)) for (s, e) in zip(splits[:-1], splits[1:]): slice_indices = [slice(None)] * module.weight.ndim slice_indices[dim] = slice(s, e) init_fn_(module.weight[slice_indices]) def generic_param_init_fn_(module: nn.Module, init_fn_, n_layers: int, d_model: Optional[int]=None, init_div_is_residual: Union[int, float, str, bool]=True, emb_init_std: Optional[float]=None, emb_init_uniform_lim: Optional[Union[Tuple[float, float], float]]=None, verbose: int=0, **kwargs): del kwargs if verbose > 1: warnings.warn(f'If model has bias parameters they are initialized to 0.') init_div_is_residual = init_div_is_residual if init_div_is_residual is False: div_is_residual = 1.0 elif init_div_is_residual is True: div_is_residual = math.sqrt(2 * n_layers) elif isinstance(init_div_is_residual, float) or isinstance(init_div_is_residual, int): div_is_residual = init_div_is_residual elif isinstance(init_div_is_residual, str) and init_div_is_residual.isnumeric(): div_is_residual = float(init_div_is_residual) else: div_is_residual = 1.0 raise ValueError(f'Expected init_div_is_residual to be boolean or numeric, got {init_div_is_residual}') if init_div_is_residual is not False: if verbose > 1: warnings.warn(f'Initializing _is_residual layers then dividing them by {div_is_residual:.3f}. ' + f'Set `init_div_is_residual: false` in init config to disable this.') if isinstance(module, nn.Linear): if hasattr(module, '_fused'): fused_init_helper_(module, init_fn_) else: init_fn_(module.weight) if module.bias is not None: torch.nn.init.zeros_(module.bias) if init_div_is_residual is not False and getattr(module, '_is_residual', False): with torch.no_grad(): module.weight.div_(div_is_residual) elif isinstance(module, nn.Embedding): if emb_init_std is not None: std = emb_init_std if std == 0: warnings.warn(f'Embedding layer initialized to 0.') emb_init_fn_ = partial(torch.nn.init.normal_, mean=0.0, std=std) if verbose > 1: warnings.warn(f'Embedding layer initialized using normal distribution with mean=0 and std={std!r}.') elif emb_init_uniform_lim is not None: lim = emb_init_uniform_lim if isinstance(lim, Sequence): if len(lim) > 2: raise ValueError(f'Uniform init requires a min and a max limit. User input: {lim}.') if lim[0] == lim[1]: warnings.warn(f'Embedding layer initialized to {lim[0]}.') else: if lim == 0: warnings.warn(f'Embedding layer initialized to 0.') lim = [-lim, lim] (a, b) = lim emb_init_fn_ = partial(torch.nn.init.uniform_, a=a, b=b) if verbose > 1: warnings.warn(f'Embedding layer initialized using uniform distribution in range {lim}.') else: emb_init_fn_ = init_fn_ emb_init_fn_(module.weight) elif isinstance(module, tuple(set(NORM_CLASS_REGISTRY.values()))): if verbose > 1: warnings.warn(f'Norm weights are set to 1. If norm layer has a bias it is initialized to 0.') if hasattr(module, 'weight') and module.weight is not None: torch.nn.init.ones_(module.weight) if hasattr(module, 'bias') and module.bias is not None: torch.nn.init.zeros_(module.bias) elif isinstance(module, nn.MultiheadAttention): if module._qkv_same_embed_dim: assert module.in_proj_weight is not None assert module.q_proj_weight is None and module.k_proj_weight is None and (module.v_proj_weight is None) assert d_model is not None _d = d_model splits = (0, _d, 2 * _d, 3 * _d) for (s, e) in zip(splits[:-1], splits[1:]): init_fn_(module.in_proj_weight[s:e]) else: assert module.q_proj_weight is not None and module.k_proj_weight is not None and (module.v_proj_weight is not None) assert module.in_proj_weight is None init_fn_(module.q_proj_weight) init_fn_(module.k_proj_weight) init_fn_(module.v_proj_weight) if module.in_proj_bias is not None: torch.nn.init.zeros_(module.in_proj_bias) if module.bias_k is not None: torch.nn.init.zeros_(module.bias_k) if module.bias_v is not None: torch.nn.init.zeros_(module.bias_v) init_fn_(module.out_proj.weight) if init_div_is_residual is not False and getattr(module.out_proj, '_is_residual', False): with torch.no_grad(): module.out_proj.weight.div_(div_is_residual) if module.out_proj.bias is not None: torch.nn.init.zeros_(module.out_proj.bias) else: for _ in module.parameters(recurse=False): raise NotImplementedError(f'{module.__class__.__name__} parameters are not initialized by param_init_fn.') def _normal_init_(std, mean=0.0): return partial(torch.nn.init.normal_, mean=mean, std=std) def _normal_param_init_fn_(module: nn.Module, std: float, n_layers: int, d_model: Optional[int]=None, init_div_is_residual: Union[int, float, str, bool]=True, emb_init_std: Optional[float]=None, emb_init_uniform_lim: Optional[Union[Tuple[float, float], float]]=None, verbose: int=0, **kwargs): del kwargs init_fn_ = _normal_init_(std=std) if verbose > 1: warnings.warn(f'Using torch.nn.init.normal_ init fn mean=0.0, std={std}') generic_param_init_fn_(module=module, init_fn_=init_fn_, d_model=d_model, n_layers=n_layers, init_div_is_residual=init_div_is_residual, emb_init_std=emb_init_std, emb_init_uniform_lim=emb_init_uniform_lim, verbose=verbose) def baseline_param_init_fn_(module: nn.Module, init_std: float, n_layers: int, d_model: Optional[int]=None, init_div_is_residual: Union[int, float, str, bool]=True, emb_init_std: Optional[float]=None, emb_init_uniform_lim: Optional[Union[Tuple[float, float], float]]=None, verbose: int=0, **kwargs): del kwargs if init_std is None: raise ValueError("You must set model.init_config['init_std'] to a float value to use the default initialization scheme.") _normal_param_init_fn_(module=module, std=init_std, d_model=d_model, n_layers=n_layers, init_div_is_residual=init_div_is_residual, emb_init_std=emb_init_std, emb_init_uniform_lim=emb_init_uniform_lim, verbose=verbose) def small_param_init_fn_(module: nn.Module, n_layers: int, d_model: int, init_div_is_residual: Union[int, float, str, bool]=True, emb_init_std: Optional[float]=None, emb_init_uniform_lim: Optional[Union[Tuple[float, float], float]]=None, verbose: int=0, **kwargs): del kwargs std = math.sqrt(2 / (5 * d_model)) _normal_param_init_fn_(module=module, std=std, d_model=d_model, n_layers=n_layers, init_div_is_residual=init_div_is_residual, emb_init_std=emb_init_std, emb_init_uniform_lim=emb_init_uniform_lim, verbose=verbose) def neox_param_init_fn_(module: nn.Module, n_layers: int, d_model: int, emb_init_std: Optional[float]=None, emb_init_uniform_lim: Optional[Union[Tuple[float, float], float]]=None, verbose: int=0, **kwargs): """From section 2.3.1 of GPT-NeoX-20B: An Open-Source AutoregressiveLanguage Model — Black et. al. (2022) see https://github.com/EleutherAI/gpt-neox/blob/9610391ab319403cef079b438edd016a2443af54/megatron/model/init_functions.py#L151 and https://github.com/EleutherAI/gpt-neox/blob/main/megatron/model/transformer.py """ del kwargs residual_div = n_layers / math.sqrt(10) if verbose > 1: warnings.warn(f'setting init_div_is_residual to {residual_div}') small_param_init_fn_(module=module, d_model=d_model, n_layers=n_layers, init_div_is_residual=residual_div, emb_init_std=emb_init_std, emb_init_uniform_lim=emb_init_uniform_lim, verbose=verbose) def kaiming_uniform_param_init_fn_(module: nn.Module, n_layers: int, d_model: Optional[int]=None, init_div_is_residual: Union[int, float, str, bool]=True, emb_init_std: Optional[float]=None, emb_init_uniform_lim: Optional[Union[Tuple[float, float], float]]=None, init_gain: float=0, fan_mode: str='fan_in', init_nonlinearity: str='leaky_relu', verbose: int=0, **kwargs): del kwargs if verbose > 1: warnings.warn(f'Using nn.init.kaiming_uniform_ init fn with parameters: ' + f'a={init_gain}, mode={fan_mode}, nonlinearity={init_nonlinearity}') kaiming_uniform_ = partial(nn.init.kaiming_uniform_, a=init_gain, mode=fan_mode, nonlinearity=init_nonlinearity) generic_param_init_fn_(module=module, init_fn_=kaiming_uniform_, d_model=d_model, n_layers=n_layers, init_div_is_residual=init_div_is_residual, emb_init_std=emb_init_std, emb_init_uniform_lim=emb_init_uniform_lim, verbose=verbose) def kaiming_normal_param_init_fn_(module: nn.Module, n_layers: int, d_model: Optional[int]=None, init_div_is_residual: Union[int, float, str, bool]=True, emb_init_std: Optional[float]=None, emb_init_uniform_lim: Optional[Union[Tuple[float, float], float]]=None, init_gain: float=0, fan_mode: str='fan_in', init_nonlinearity: str='leaky_relu', verbose: int=0, **kwargs): del kwargs if verbose > 1: warnings.warn(f'Using nn.init.kaiming_normal_ init fn with parameters: ' + f'a={init_gain}, mode={fan_mode}, nonlinearity={init_nonlinearity}') kaiming_normal_ = partial(torch.nn.init.kaiming_normal_, a=init_gain, mode=fan_mode, nonlinearity=init_nonlinearity) generic_param_init_fn_(module=module, init_fn_=kaiming_normal_, d_model=d_model, n_layers=n_layers, init_div_is_residual=init_div_is_residual, emb_init_std=emb_init_std, emb_init_uniform_lim=emb_init_uniform_lim, verbose=verbose) def xavier_uniform_param_init_fn_(module: nn.Module, n_layers: int, d_model: Optional[int]=None, init_div_is_residual: Union[int, float, str, bool]=True, emb_init_std: Optional[float]=None, emb_init_uniform_lim: Optional[Union[Tuple[float, float], float]]=None, init_gain: float=0, verbose: int=0, **kwargs): del kwargs xavier_uniform_ = partial(torch.nn.init.xavier_uniform_, gain=init_gain) if verbose > 1: warnings.warn(f'Using torch.nn.init.xavier_uniform_ init fn with parameters: ' + f'gain={init_gain}') generic_param_init_fn_(module=module, init_fn_=xavier_uniform_, d_model=d_model, n_layers=n_layers, init_div_is_residual=init_div_is_residual, emb_init_std=emb_init_std, emb_init_uniform_lim=emb_init_uniform_lim, verbose=verbose) def xavier_normal_param_init_fn_(module: nn.Module, n_layers: int, d_model: Optional[int]=None, init_div_is_residual: Union[int, float, str, bool]=True, emb_init_std: Optional[float]=None, emb_init_uniform_lim: Optional[Union[Tuple[float, float], float]]=None, init_gain: float=0, verbose: int=0, **kwargs): xavier_normal_ = partial(torch.nn.init.xavier_normal_, gain=init_gain) if verbose > 1: warnings.warn(f'Using torch.nn.init.xavier_normal_ init fn with parameters: ' + f'gain={init_gain}') generic_param_init_fn_(module=module, init_fn_=xavier_normal_, d_model=d_model, n_layers=n_layers, init_div_is_residual=init_div_is_residual, emb_init_std=emb_init_std, emb_init_uniform_lim=emb_init_uniform_lim, verbose=verbose) MODEL_INIT_REGISTRY = {'default_': torch_default_param_init_fn_, 'baseline_': baseline_param_init_fn_, 'kaiming_uniform_': kaiming_uniform_param_init_fn_, 'kaiming_normal_': kaiming_normal_param_init_fn_, 'neox_init_': neox_param_init_fn_, 'small_init_': small_param_init_fn_, 'xavier_uniform_': xavier_uniform_param_init_fn_, 'xavier_normal_': xavier_normal_param_init_fn_}