# Copyright 2022 MosaicML Examples authors
# SPDX-License-Identifier: Apache-2.0
"""A HuggingFace-style model configuration."""
from typing import Optional, Tuple, Union
from transformers import PretrainedConfig
class MosaicGPTConfig(PretrainedConfig):
model_type = 'mosaic_gpt'
def __init__(
self,
d_model: int = 2048,
n_heads: int = 16,
n_layers: int = 24,
mlp_ratio: int = 4,
max_seq_len: int = 2048,
vocab_size: int = 50368,
attn_pdrop: float = 0.0,
resid_pdrop: float = 0.0,
emb_pdrop: float = 0.0,
attn_impl: str = 'triton',
attn_qk_ln: bool = False,
attn_clip_qkv: Optional[float] = None,
softmax_scale: Optional[float] = None,
prefix_lm: Optional[bool] = False,
attn_uses_sequence_id: Optional[bool] = False,
alibi: bool = False,
alibi_bias_max: int = 8,
init_device: str = 'cpu',
logit_scale: Optional[Union[float, str]] = None,
no_bias: bool = False,
verbose: int = 0,
param_init_fn: str = 'kaiming_normal_',
init_div_is_residual: Union[int, float, str, bool] = True,
init_std: float = 0.02,
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 = 'relu',
embedding_fraction: float = 1.0,
low_precision_layernorm: bool = True,
use_cache: bool = False,
**kwargs,
):
"""The MosaicGPT configuration class.
Args:
d_model (int): The size of the embedding dimension of the model.
n_heads (int): The number of attention heads.
n_layers (int): The number of layers in the model.
mlp_ratio (int): The ratio of the up/down scale in the MLP.
max_seq_len (int): The maximum sequence length of the model.
vocab_size (int): The size of the vocabulary.
attn_pdrop (float): The dropout probability for the attention layers.
resid_pdrop (float): The dropout probability applied to the attention output before combining with residual.
emb_pdrop (float): The dropout probability for the embedding layer.
attn_impl (str): The attention implementation to use. One of 'torch', 'flash', or 'triton'.
attn_qk_ln (bool): Whether to apply layer normalization to the queries and keys in the attention layer.
attn_clip_qkv (Optional[float]): If not None, clip the queries, keys, and values in the attention layer to
this value.
softmax_scale (Optional[float]): If not None, scale the softmax in the attention layer by this value. If None,
use the default scale of ``1/sqrt(d_keys)``.
prefix_lm (Optional[bool]): Whether the model should operate as a Prefix LM. This requires passing an
extra `prefix_mask` argument which indicates which tokens belong to the prefix. Tokens in the prefix
can attend to one another bi-directionally. Tokens outside the prefix use causal attention.
attn_uses_sequence_id (Optional[bool]): Whether to restrict attention to tokens that have the same sequence_id.
When the model is in `train` mode, this requires passing an extra `sequence_id` argument which indicates
which sub-sequence each token belongs to.
Defaults to ``False`` meaning any provided `sequence_id` will be ignored.
alibi (bool): Whether to use the alibi bias instead of position embeddings.
alibi_bias_max (int): The maximum value of the alibi bias.
init_device (str): The device to use for parameter initialization.
logit_scale (Optional[Union[float, str]]): If not None, scale the logits by this value.
no_bias (bool): Whether to use bias in all layers.
verbose (int): The verbosity level. 0 is silent.
param_init_fn (str): The parameter initialization scheme to use. One of 'default_', 'baseline_', 'kaiming_uniform_',
'kaiming_normal_', 'neox_init_', 'small_init_', 'xavier_uniform_', or 'xavier_normal_'.
init_div_is_residual (Union[int, float, str, bool]): Value to divide initial weights by if ``module._is_residual`` is True.
init_std (float): The standard deviation of the normal distribution used to initialize the model,
if using the baseline_ parameter initialization scheme.
emb_init_std (Optional[float]): The standard deviation of the normal distribution used to initialize the embedding layer.
emb_init_uniform_lim (Optional[Union[Tuple[float, float], float]]): The lower and upper limits of the uniform distribution
used to initialize the embedding layer. Mutually exclusive with ``emb_init_std``.
init_gain (float): The gain to use for parameter initialization with kaiming or xavier initialization schemes.
fan_mode (str): The fan mode to use for parameter initialization with kaiming initialization schemes.
init_nonlinearity (str): The nonlinearity to use for parameter initialization with kaiming initialization schemes.
embedding_fraction (float): The fraction to scale the gradients of the embedding layer by.
low_precision_layernorm (bool): Whether to use low precision layer normalization.
use_cache (bool): Whether or not the model should return the last key/values attentions
"""
self.d_model = d_model
self.n_heads = n_heads
self.n_layers = n_layers
self.mlp_ratio = mlp_ratio
self.max_seq_len = max_seq_len
self.vocab_size = vocab_size
self.attn_pdrop = attn_pdrop
self.resid_pdrop = resid_pdrop
self.emb_pdrop = emb_pdrop
self.attn_impl = attn_impl
self.attn_qk_ln = attn_qk_ln
self.attn_clip_qkv = attn_clip_qkv
self.softmax_scale = softmax_scale
self.prefix_lm = prefix_lm
self.attn_uses_sequence_id = attn_uses_sequence_id
self.alibi = alibi
self.alibi_bias_max = alibi_bias_max
self.init_device = init_device
self.logit_scale = logit_scale
self.no_bias = no_bias
self.verbose = verbose
self.param_init_fn = param_init_fn
self.init_div_is_residual = init_div_is_residual
self.init_std = init_std
self.emb_init_std = emb_init_std
self.emb_init_uniform_lim = emb_init_uniform_lim
self.init_std = init_std
self.init_gain = init_gain
self.fan_mode = fan_mode
self.init_nonlinearity = init_nonlinearity
self.embedding_fraction = embedding_fraction
self.low_precision_layernorm = low_precision_layernorm
self.use_cache = use_cache
if 'name' in kwargs:
del kwargs['name']
if 'loss_fn' in kwargs:
del kwargs['loss_fn']
super().__init__(**kwargs)
self._validate_config()
def _validate_config(self):
if self.d_model % self.n_heads != 0:
raise ValueError('d_model must be divisible by n_heads')
if any(prob < 0 or prob > 1
for prob in [self.attn_pdrop, self.resid_pdrop, self.emb_pdrop]):
raise ValueError(
'attn_pdrop, resid_pdrop, emb_pdrop are probabilities and must be between 0 and 1'
)
if self.attn_impl not in ['torch', 'flash', 'triton']:
raise ValueError(f'Unknown attn_impl={self.attn_impl}')
if self.prefix_lm and self.attn_impl not in ['torch', 'triton']:
raise NotImplementedError(
'prefix_lm only implemented with torch and triton attention.')
if self.alibi and self.attn_impl not in ['torch', 'triton']:
raise NotImplementedError(
'alibi only implemented with torch and triton attention.')
if self.attn_uses_sequence_id and self.attn_impl not in [
'torch', 'triton'
]:
raise NotImplementedError(
'attn_uses_sequence_id only implemented with torch and triton attention.'
)
if self.embedding_fraction > 1 or self.embedding_fraction <= 0:
raise ValueError(
'model.embedding_fraction must be between 0 (exclusive) and 1 (inclusive)!'
)
if isinstance(self.logit_scale,
str) and self.logit_scale != 'inv_sqrt_d_model':
raise ValueError(
f"{self.logit_scale=} is not recognized as an option; use numeric value or 'inv_sqrt_d_model'."
)