File size: 19,710 Bytes
a824a18 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 |
"""A simple, flexible implementation of a GPT model.
Inspired by https://github.com/karpathy/minGPT/blob/master/mingpt/model.py
"""
import math
import warnings
from typing import List, Optional, Tuple, Union
import torch
import torch.nn as nn
import torch.nn.functional as F
from transformers import PreTrainedModel, PreTrainedTokenizer, PreTrainedTokenizerFast
from transformers.modeling_outputs import BaseModelOutputWithPast, CausalLMOutputWithPast
from .attention import attn_bias_shape, build_attn_bias
from .blocks import MPTBlock
from .custom_embedding import SharedEmbedding
from .norm import NORM_CLASS_REGISTRY
from .configuration_mpt import MPTConfig
from .adapt_tokenizer import AutoTokenizerForMOD, adapt_tokenizer_for_denoising
from .hf_prefixlm_converter import add_bidirectional_mask_if_missing, convert_hf_causal_lm_to_prefix_lm
from .meta_init_context import init_empty_weights
from .param_init_fns import MODEL_INIT_REGISTRY, generic_param_init_fn_
try:
from .flash_attn_triton import flash_attn_func
except:
pass
Tokenizer = Union[PreTrainedTokenizer, PreTrainedTokenizerFast]
class MPTPreTrainedModel(PreTrainedModel):
config_class = MPTConfig
base_model_prefix = 'model'
_no_split_modules = ['MPTBlock']
class MPTModel(MPTPreTrainedModel):
def __init__(self, config: MPTConfig):
config._validate_config()
super().__init__(config)
self.attn_impl = config.attn_config['attn_impl']
self.prefix_lm = config.attn_config['prefix_lm']
self.attn_uses_sequence_id = config.attn_config['attn_uses_sequence_id']
self.alibi = config.attn_config['alibi']
self.alibi_bias_max = config.attn_config['alibi_bias_max']
if config.init_device == 'mixed':
if dist.get_local_rank() == 0:
config.init_device = 'cpu'
else:
config.init_device = 'meta'
if config.norm_type.lower() not in NORM_CLASS_REGISTRY.keys():
norm_options = ' | '.join(NORM_CLASS_REGISTRY.keys())
raise NotImplementedError(f'Requested norm type ({config.norm_type}) is not implemented within this repo (Options: {norm_options}).')
norm_class = NORM_CLASS_REGISTRY[config.norm_type.lower()]
self.embedding_fraction = config.embedding_fraction
self.wte = SharedEmbedding(config.vocab_size, config.d_model, device=config.init_device)
if not self.alibi:
self.wpe = torch.nn.Embedding(config.max_seq_len, config.d_model, device=config.init_device)
self.emb_drop = nn.Dropout(config.emb_pdrop)
self.blocks = nn.ModuleList([MPTBlock(device=config.init_device, **config.to_dict()) for _ in range(config.n_layers)])
self.norm_f = norm_class(config.d_model, device=config.init_device)
if config.init_device != 'meta':
print(f'You are using config.init_device={config.init_device!r}, but you can also use config.init_device="meta" with Composer + FSDP for fast initialization.')
self.apply(self.param_init_fn)
self.is_causal = not self.prefix_lm
self._attn_bias_initialized = False
self.attn_bias = None
self.attn_bias_shape = attn_bias_shape(self.attn_impl, config.n_heads, config.max_seq_len, self.alibi, prefix_lm=self.prefix_lm, causal=self.is_causal, use_sequence_id=self.attn_uses_sequence_id)
if config.no_bias:
for module in self.modules():
if hasattr(module, 'bias') and isinstance(module.bias, nn.Parameter):
if config.verbose:
warnings.warn(f'Removing bias ({module.bias}) from {module}.')
module.register_parameter('bias', None)
if config.verbose and config.verbose > 2:
print(self)
if 'verbose' not in self.config.init_config:
self.config.init_config['verbose'] = self.config.verbose
if self.config.init_config['verbose'] > 1:
init_fn_name = self.config.init_config['name']
warnings.warn(f'Using {init_fn_name} initialization.')
self.gradient_checkpointing = False
def get_input_embeddings(self):
return self.wte
def set_input_embeddings(self, value):
self.wte = value
@torch.no_grad()
def _attn_bias(self, device, dtype, attention_mask: Optional[torch.ByteTensor]=None, prefix_mask: Optional[torch.ByteTensor]=None, sequence_id: Optional[torch.LongTensor]=None):
if not self._attn_bias_initialized:
if self.attn_bias_shape:
self.attn_bias = torch.zeros(self.attn_bias_shape, device=device, dtype=dtype)
self.attn_bias = build_attn_bias(self.attn_impl, self.attn_bias, self.config.n_heads, self.config.max_seq_len, causal=self.is_causal, alibi=self.alibi, alibi_bias_max=self.alibi_bias_max)
self._attn_bias_initialized = True
if self.attn_impl == 'flash':
return (self.attn_bias, attention_mask)
if self.attn_bias is not None:
self.attn_bias = self.attn_bias.to(dtype=dtype, device=device)
attn_bias = self.attn_bias
if self.prefix_lm:
assert isinstance(attn_bias, torch.Tensor)
assert isinstance(prefix_mask, torch.Tensor)
attn_bias = self._apply_prefix_mask(attn_bias, prefix_mask)
if self.attn_uses_sequence_id and sequence_id is not None:
assert isinstance(attn_bias, torch.Tensor)
attn_bias = self._apply_sequence_id(attn_bias, sequence_id)
if attention_mask is not None:
s_k = attention_mask.shape[-1]
if attn_bias is None:
attn_bias = torch.zeros((1, 1, 1, s_k), device=device, dtype=dtype)
else:
_s_k = max(0, attn_bias.size(-1) - s_k)
attn_bias = attn_bias[:, :, :, _s_k:]
if prefix_mask is not None and attention_mask.shape != prefix_mask.shape:
raise ValueError(f'attention_mask shape={attention_mask.shape} ' + f'and prefix_mask shape={prefix_mask.shape} are not equal.')
min_val = torch.finfo(attn_bias.dtype).min
attn_bias = attn_bias.masked_fill(~attention_mask.view(-1, 1, 1, s_k), min_val)
return (attn_bias, None)
def _apply_prefix_mask(self, attn_bias: torch.Tensor, prefix_mask: torch.Tensor):
(s_k, s_q) = attn_bias.shape[-2:]
if s_k != self.config.max_seq_len or s_q != self.config.max_seq_len:
raise ValueError('attn_bias does not match the expected shape. ' + f'The last two dimensions should both be {self.config.max_length} ' + f'but are {s_k} and {s_q}.')
seq_len = prefix_mask.shape[-1]
if seq_len > self.config.max_seq_len:
raise ValueError(f'prefix_mask sequence length cannot exceed max_seq_len={self.config.max_seq_len}')
attn_bias = attn_bias[..., :seq_len, :seq_len]
causal = torch.tril(torch.ones((seq_len, seq_len), dtype=torch.bool, device=prefix_mask.device)).view(1, 1, seq_len, seq_len)
prefix = prefix_mask.view(-1, 1, 1, seq_len)
cannot_attend = ~torch.logical_or(causal, prefix.bool())
min_val = torch.finfo(attn_bias.dtype).min
attn_bias = attn_bias.masked_fill(cannot_attend, min_val)
return attn_bias
def _apply_sequence_id(self, attn_bias: torch.Tensor, sequence_id: torch.LongTensor):
seq_len = sequence_id.shape[-1]
if seq_len > self.config.max_seq_len:
raise ValueError(f'sequence_id sequence length cannot exceed max_seq_len={self.config.max_seq_len}')
attn_bias = attn_bias[..., :seq_len, :seq_len]
cannot_attend = torch.logical_not(torch.eq(sequence_id.view(-1, seq_len, 1), sequence_id.view(-1, 1, seq_len))).unsqueeze(1)
min_val = torch.finfo(attn_bias.dtype).min
attn_bias = attn_bias.masked_fill(cannot_attend, min_val)
return attn_bias
def forward(self, input_ids: torch.LongTensor, past_key_values: Optional[List[Tuple[torch.FloatTensor]]]=None, attention_mask: Optional[torch.ByteTensor]=None, prefix_mask: Optional[torch.ByteTensor]=None, sequence_id: Optional[torch.LongTensor]=None, return_dict: Optional[bool]=None, output_attentions: Optional[bool]=None, output_hidden_states: Optional[bool]=None, use_cache: Optional[bool]=None, inputs_embeds: Optional[torch.Tensor]=None):
return_dict = return_dict if return_dict is not None else self.config.return_dict
use_cache = use_cache if use_cache is not None else self.config.use_cache
if attention_mask is not None:
attention_mask = attention_mask.bool()
if prefix_mask is not None:
prefix_mask = prefix_mask.bool()
if not return_dict:
raise NotImplementedError('return_dict False is not implemented yet for MPT')
if output_attentions:
if self.attn_impl != 'torch':
raise NotImplementedError('output_attentions is not implemented for MPT when using attn_impl `flash` or `triton`.')
if attention_mask is not None and attention_mask[:, 0].sum() != attention_mask.shape[0] and self.training:
raise NotImplementedError('MPT does not support training with left padding.')
if self.prefix_lm and prefix_mask is None:
raise ValueError('prefix_mask is a required argument when MPT is configured with prefix_lm=True.')
if self.training:
if self.attn_uses_sequence_id and sequence_id is None:
raise ValueError('sequence_id is a required argument when MPT is configured with attn_uses_sequence_id=True ' + 'and the model is in train mode.')
elif self.attn_uses_sequence_id is False and sequence_id is not None:
warnings.warn('MPT received non-None input for `sequence_id` but is configured with attn_uses_sequence_id=False. ' + 'This input will be ignored. If you want the model to use `sequence_id`, set attn_uses_sequence_id to True.')
if input_ids is not None:
S = input_ids.size(1)
assert S <= self.config.max_seq_len, f'Cannot forward input with seq_len={S}, this model only supports seq_len<={self.config.max_seq_len}'
tok_emb = self.wte(input_ids)
else:
assert inputs_embeds is not None
assert self.alibi, 'inputs_embeds is not implemented for MPT unless for alibi.'
S = inputs_embeds.size(1)
tok_emb = inputs_embeds
if self.alibi:
x = tok_emb
else:
past_position = 0
if past_key_values is not None:
if len(past_key_values) != self.config.n_layers:
raise ValueError(f'past_key_values must provide a past_key_value for each attention ' + f'layer in the network (len(past_key_values)={len(past_key_values)!r}; self.config.n_layers={self.config.n_layers!r}).')
past_position = past_key_values[0][0].size(1)
if self.attn_impl == 'torch':
past_position = past_key_values[0][0].size(3)
if S + past_position > self.config.max_seq_len:
raise ValueError(f'Cannot forward input with past sequence length {past_position} and current sequence length {S + 1}, this model only supports total sequence length <= {self.config.max_seq_len}.')
pos = torch.arange(past_position, S + past_position, dtype=torch.long, device=input_ids.device).unsqueeze(0)
if attention_mask is not None:
pos = torch.clamp(pos - torch.cumsum((~attention_mask).to(torch.int32), dim=1)[:, past_position:], min=0)
pos_emb = self.wpe(pos)
x = tok_emb + pos_emb
if self.embedding_fraction == 1:
x = self.emb_drop(x)
else:
x_shrunk = x * self.embedding_fraction + x.detach() * (1 - self.embedding_fraction)
assert isinstance(self.emb_drop, nn.Module)
x = self.emb_drop(x_shrunk)
(attn_bias, attention_mask) = self._attn_bias(device=x.device, dtype=torch.float32, attention_mask=attention_mask, prefix_mask=prefix_mask, sequence_id=sequence_id)
if use_cache and past_key_values is None:
past_key_values = [() for _ in range(self.config.n_layers)]
all_hidden_states = () if output_hidden_states else None
all_self_attns = () if output_attentions else None
for (b_idx, block) in enumerate(self.blocks):
if output_hidden_states:
assert all_hidden_states is not None
all_hidden_states = all_hidden_states + (x,)
past_key_value = past_key_values[b_idx] if past_key_values is not None else None
if self.gradient_checkpointing and self.training:
(x, attn_weights, past_key_value) = torch.utils.checkpoint.checkpoint(block, x, past_key_value, attn_bias, attention_mask, self.is_causal)
else:
(x, attn_weights, past_key_value) = block(x, past_key_value=past_key_value, attn_bias=attn_bias, attention_mask=attention_mask, is_causal=self.is_causal)
if past_key_values is not None:
past_key_values[b_idx] = past_key_value
if output_attentions:
assert all_self_attns is not None
all_self_attns = all_self_attns + (attn_weights,)
x = self.norm_f(x)
if output_hidden_states:
assert all_hidden_states is not None
all_hidden_states = all_hidden_states + (x,)
return BaseModelOutputWithPast(last_hidden_state=x, past_key_values=past_key_values, hidden_states=all_hidden_states, attentions=all_self_attns)
def param_init_fn(self, module):
init_fn_name = self.config.init_config['name']
MODEL_INIT_REGISTRY[init_fn_name](module=module, n_layers=self.config.n_layers, d_model=self.config.d_model, **self.config.init_config)
def fsdp_wrap_fn(self, module):
return isinstance(module, MPTBlock)
def activation_checkpointing_fn(self, module):
return isinstance(module, MPTBlock)
class MPTForCausalLM(MPTPreTrainedModel):
def __init__(self, config: MPTConfig):
super().__init__(config)
if not config.tie_word_embeddings:
raise ValueError('MPTForCausalLM only supports tied word embeddings')
print(f'Instantiating an MPTForCausalLM model from {__file__}')
self.transformer = MPTModel(config)
for child in self.transformer.children():
if isinstance(child, torch.nn.ModuleList):
continue
if isinstance(child, torch.nn.Module):
child._fsdp_wrap = True
self.logit_scale = None
if config.logit_scale is not None:
logit_scale = config.logit_scale
if isinstance(logit_scale, str):
if logit_scale == 'inv_sqrt_d_model':
logit_scale = 1 / math.sqrt(config.d_model)
else:
raise ValueError(f"logit_scale={logit_scale!r} is not recognized as an option; use numeric value or 'inv_sqrt_d_model'.")
self.logit_scale = logit_scale
def get_input_embeddings(self):
return self.transformer.wte
def set_input_embeddings(self, value):
self.transformer.wte = value
def get_output_embeddings(self):
return self.transformer.wte
def set_output_embeddings(self, new_embeddings):
self.transformer.wte = new_embeddings
def set_decoder(self, decoder):
self.transformer = decoder
def get_decoder(self):
return self.transformer
def forward(self, input_ids: torch.LongTensor, past_key_values: Optional[List[Tuple[torch.FloatTensor]]]=None, attention_mask: Optional[torch.ByteTensor]=None, prefix_mask: Optional[torch.ByteTensor]=None, sequence_id: Optional[torch.LongTensor]=None, labels: Optional[torch.LongTensor]=None, return_dict: Optional[bool]=None, output_attentions: Optional[bool]=None, output_hidden_states: Optional[bool]=None, use_cache: Optional[bool]=None, inputs_embeds: Optional[torch.FloatTensor]=None):
return_dict = return_dict if return_dict is not None else self.config.return_dict
use_cache = use_cache if use_cache is not None else self.config.use_cache
if inputs_embeds is not None:
raise NotImplementedError('inputs_embeds has to be None (for hf/peft support).')
outputs = self.transformer(input_ids=input_ids, past_key_values=past_key_values, attention_mask=attention_mask, prefix_mask=prefix_mask, sequence_id=sequence_id, return_dict=return_dict, output_attentions=output_attentions, output_hidden_states=output_hidden_states, use_cache=use_cache)
logits = self.transformer.wte(outputs.last_hidden_state.to(self.transformer.wte.weight.device), True)
if self.logit_scale is not None:
if self.logit_scale == 0:
warnings.warn(f'Multiplying logits by self.logit_scale={self.logit_scale!r}. This will produce uniform (uninformative) outputs.')
logits *= self.logit_scale
loss = None
if labels is not None:
labels = torch.roll(labels, shifts=-1)
labels[:, -1] = -100
loss = F.cross_entropy(logits.view(-1, logits.size(-1)), labels.to(logits.device).view(-1))
return CausalLMOutputWithPast(loss=loss, logits=logits, past_key_values=outputs.past_key_values, hidden_states=outputs.hidden_states, attentions=outputs.attentions)
def param_init_fn(self, module):
init_fn_name = self.config.init_config['name']
MODEL_INIT_REGISTRY[init_fn_name](module=module, n_layers=self.config.n_layers, d_model=self.config.d_model, **self.config.init_config)
def fsdp_wrap_fn(self, module):
return isinstance(module, MPTBlock)
def activation_checkpointing_fn(self, module):
return isinstance(module, MPTBlock)
def prepare_inputs_for_generation(self, input_ids, past_key_values=None, inputs_embeds=None, **kwargs):
if inputs_embeds is not None:
raise NotImplementedError('inputs_embeds is not implemented for MPT yet')
attention_mask = kwargs['attention_mask'].bool()
if attention_mask[:, -1].sum() != attention_mask.shape[0]:
raise NotImplementedError('MPT does not support generation with right padding.')
if self.transformer.attn_uses_sequence_id and self.training:
sequence_id = torch.zeros_like(input_ids[:1])
else:
sequence_id = None
if past_key_values is not None:
input_ids = input_ids[:, -1].unsqueeze(-1)
if self.transformer.prefix_lm:
prefix_mask = torch.ones_like(attention_mask)
if kwargs.get('use_cache') == False:
raise NotImplementedError('MPT with prefix_lm=True does not support use_cache=False.')
else:
prefix_mask = None
return {'input_ids': input_ids, 'attention_mask': attention_mask, 'prefix_mask': prefix_mask, 'sequence_id': sequence_id, 'past_key_values': past_key_values, 'use_cache': kwargs.get('use_cache', True)}
@staticmethod
def _reorder_cache(past_key_values, beam_idx):
"""Used by HuggingFace generate when using beam search with kv-caching.
See https://github.com/huggingface/transformers/blob/3ec7a47664ebe40c40f4b722f6bb1cd30c3821ec/src/transformers/models/gpt2/modeling_gpt2.py#L1122-L1133
for an example in transformers.
"""
reordered_past = []
for layer_past in past_key_values:
reordered_past += [tuple((past_state.index_select(0, beam_idx) for past_state in layer_past))]
return reordered_past |