File size: 14,610 Bytes
3440f83 |
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 |
# Copyright (c) 2022 Microsoft
# Licensed under The MIT License [see LICENSE for details]
import math
import numpy as np
import torch
import torch.nn as nn
from fairscale.nn import checkpoint_wrapper, wrap
from vlmo.torchscale.architecture.utils import init_bert_params
from vlmo.torchscale.component.droppath import DropPath
from vlmo.torchscale.component.feedforward_network import FeedForwardNetwork, make_experts
from vlmo.torchscale.component.multihead_attention import MultiheadAttention
from vlmo.torchscale.component.relative_position_bias import RelativePositionBias
#from vlmo.torchscale.component.xmoe.moe_layer import MOELayer
#from vlmo.torchscale.component.xmoe.routing import Top1Gate, Top2Gate
try:
from apex.normalization import FusedLayerNorm as LayerNorm
except ModuleNotFoundError:
from torch.nn import LayerNorm
class DecoderLayer(nn.Module):
def __init__(
self,
args,
depth,
is_moe_layer=False,
is_encoder_decoder=False,
):
super().__init__()
self.args = args
self.embed_dim = args.decoder_embed_dim
self.dropout_module = torch.nn.Dropout(args.dropout)
if args.drop_path_rate > 0:
drop_path_prob = np.linspace(0, args.drop_path_rate, args.decoder_layers)[depth]
self.drop_path = DropPath(drop_path_prob)
else:
self.drop_path = None
self.self_attn = self.build_self_attention(self.embed_dim, args)
self.normalize_before = args.decoder_normalize_before
self.self_attn_layer_norm = LayerNorm(self.embed_dim, eps=args.layernorm_eps)
if not is_encoder_decoder:
self.encoder_attn = None
self.encoder_attn_layer_norm = None
else:
self.encoder_attn = self.build_encoder_attention(self.embed_dim, args)
self.encoder_attn_layer_norm = LayerNorm(self.embed_dim, eps=args.layernorm_eps)
self.is_moe_layer = is_moe_layer
self.ffn_dim = args.decoder_ffn_embed_dim
if not self.is_moe_layer:
self.ffn = self.build_ffn(
self.embed_dim,
self.args,
)
else:
if args.moe_top1_expert:
gate = Top1Gate(
self.embed_dim,
args.moe_expert_count,
use_fp32=args.moe_gating_use_fp32,
moe_eval_capacity_token_fraction=args.moe_eval_capacity_token_fraction,
use_xmoe=args.use_xmoe,
)
else:
gate = Top2Gate(
self.embed_dim,
args.moe_expert_count,
args.moe_gating_use_fp32,
args.moe_second_expert_policy,
args.moe_normalize_gate_prob_before_dropping,
args.moe_eval_capacity_token_fraction,
use_xmoe=args.use_xmoe,
)
experts = make_experts(args, self.embed_dim, self.ffn_dim)
self.moe_layer = MOELayer(gate, experts, args)
self.final_layer_norm = LayerNorm(self.embed_dim, eps=args.layernorm_eps)
if args.deepnorm:
if is_encoder_decoder:
self.alpha = math.pow(3.0 * args.decoder_layers, 0.25)
else:
self.alpha = math.pow(2.0 * args.decoder_layers, 0.25)
else:
self.alpha = 1.0
def build_ffn(self, embed_dim, args):
return FeedForwardNetwork(
embed_dim,
self.ffn_dim,
args.activation_fn,
args.dropout,
args.activation_dropout,
args.layernorm_eps,
args.subln,
)
def build_self_attention(self, embed_dim, args):
return MultiheadAttention(
args,
embed_dim,
args.decoder_attention_heads,
dropout=args.attention_dropout,
self_attention=True,
encoder_decoder_attention=False,
subln=args.subln,
)
def build_encoder_attention(self, embed_dim, args):
return MultiheadAttention(
args,
embed_dim,
args.decoder_attention_heads,
dropout=args.attention_dropout,
self_attention=False,
encoder_decoder_attention=True,
subln=args.subln,
)
def residual_connection(self, x, residual):
return residual * self.alpha + x
def forward(
self,
x,
encoder_out=None,
encoder_padding_mask=None,
incremental_state=None,
self_attn_mask=None,
self_attn_padding_mask=None,
self_attn_rel_pos=None,
cross_attn_rel_pos=None,
):
residual = x
if self.normalize_before:
x = self.self_attn_layer_norm(x)
x, attn = self.self_attn(
query=x,
key=x,
value=x,
key_padding_mask=self_attn_padding_mask,
incremental_state=incremental_state,
attn_mask=self_attn_mask,
rel_pos=self_attn_rel_pos,
)
x = self.dropout_module(x)
if self.drop_path is not None:
x = self.drop_path(x)
x = self.residual_connection(x, residual)
if not self.normalize_before:
x = self.self_attn_layer_norm(x)
if self.encoder_attn is not None and encoder_out is not None:
residual = x
if self.normalize_before:
x = self.encoder_attn_layer_norm(x)
x, attn = self.encoder_attn(
query=x,
key=encoder_out,
value=encoder_out,
key_padding_mask=encoder_padding_mask,
incremental_state=None,
rel_pos=cross_attn_rel_pos,
)
x = self.dropout_module(x)
if self.drop_path is not None:
x = self.drop_path(x)
x = self.residual_connection(x, residual)
if not self.normalize_before:
x = self.encoder_attn_layer_norm(x)
residual = x
if self.normalize_before:
x = self.final_layer_norm(x)
if not self.is_moe_layer:
x = self.ffn(x)
l_aux = None
else:
x, l_aux = self.moe_layer(x)
if self.drop_path is not None:
x = self.drop_path(x)
x = self.residual_connection(x, residual)
if not self.normalize_before:
x = self.final_layer_norm(x)
return x, attn, None, l_aux
class Decoder(nn.Module):
def __init__(
self, args, embed_tokens=None, embed_positions=None, output_projection=None, is_encoder_decoder=False, **kwargs
):
super().__init__(**kwargs)
self.args = args
self.dropout_module = torch.nn.Dropout(args.dropout)
embed_dim = args.decoder_embed_dim
self.embed_dim = embed_dim
self.embed_scale = 1.0 if args.no_scale_embedding else math.sqrt(embed_dim)
self.embed_tokens = embed_tokens
self.embed_positions = embed_positions
if output_projection is None and not args.no_output_layer and args.vocab_size > 0:
self.output_projection = self.build_output_projection(args)
else:
self.output_projection = output_projection
if args.layernorm_embedding:
self.layernorm_embedding = LayerNorm(embed_dim, eps=args.layernorm_eps)
else:
self.layernorm_embedding = None
self.layers = nn.ModuleList([])
moe_freq = args.moe_freq
for i in range(args.decoder_layers):
is_moe_layer = moe_freq != 0 and (i + 1) % moe_freq == 0
self.layers.append(
self.build_decoder_layer(
args,
depth=i,
is_moe_layer=is_moe_layer,
is_encoder_decoder=is_encoder_decoder,
)
)
self.num_layers = len(self.layers)
if args.decoder_normalize_before:
self.layer_norm = LayerNorm(embed_dim, eps=args.layernorm_eps)
else:
self.layer_norm = None
self.self_attn_relative_position = None
self.cross_attn_relative_position = None
if args.rel_pos_buckets > 0 and args.max_rel_pos > 0:
self.self_attn_relative_position = RelativePositionBias(
num_buckets=args.rel_pos_buckets,
max_distance=args.max_rel_pos,
n_heads=args.decoder_attention_heads,
)
if is_encoder_decoder:
self.cross_attn_relative_position = RelativePositionBias(
num_buckets=args.rel_pos_buckets,
max_distance=args.max_rel_pos,
n_heads=args.decoder_attention_heads,
)
if args.bert_init:
self.apply(init_bert_params)
if args.deepnorm:
if is_encoder_decoder:
init_scale = math.pow(12.0 * args.decoder_layers, 0.25)
else:
init_scale = math.pow(8.0 * args.decoder_layers, 0.25)
for name, p in self.named_parameters():
if "fc1" in name or "fc2" in name or "out_proj" in name or "v_proj" in name:
p.data.div_(init_scale)
if args.subln:
if is_encoder_decoder:
init_scale = math.sqrt(math.log(args.decoder_layers * 3))
else:
init_scale = math.sqrt(math.log(args.decoder_layers * 2))
for name, p in self.named_parameters():
if "encoder_attn" in name:
continue
if "fc1" in name or "fc2" in name or "out_proj" in name or "v_proj" in name:
p.data.mul_(init_scale)
def build_output_projection(
self,
args,
):
if args.share_decoder_input_output_embed:
output_projection = torch.nn.Linear(
self.embed_tokens.weight.shape[1],
self.embed_tokens.weight.shape[0],
bias=False,
)
output_projection.weight = self.embed_tokens.weight
else:
output_projection = torch.nn.Linear(args.decoder_embed_dim, args.vocab_size, bias=False)
torch.nn.init.normal_(output_projection.weight, mean=0, std=args.decoder_embed_dim**-0.5)
return output_projection
def build_decoder_layer(self, args, depth, is_moe_layer=False, is_encoder_decoder=False):
layer = DecoderLayer(
args,
depth,
is_moe_layer=is_moe_layer,
is_encoder_decoder=is_encoder_decoder,
)
if args.checkpoint_activations:
layer = checkpoint_wrapper(layer)
if args.fsdp:
layer = wrap(layer)
return layer
def forward_embedding(
self,
tokens,
token_embedding=None,
incremental_state=None,
):
positions = None
if self.embed_positions is not None:
positions = self.embed_positions(tokens, incremental_state=incremental_state)
if incremental_state is not None:
tokens = tokens[:, -1:]
if positions is not None:
positions = positions[:, -1:]
if token_embedding is None:
token_embedding = self.embed_tokens(tokens)
x = embed = self.embed_scale * token_embedding
if positions is not None:
x += positions
if self.layernorm_embedding is not None:
x = self.layernorm_embedding(x)
x = self.dropout_module(x)
return x, embed
def forward(
self,
prev_output_tokens,
self_attn_padding_mask=None,
encoder_out=None,
incremental_state=None,
features_only=False,
return_all_hiddens=False,
token_embeddings=None,
**kwargs
):
# embed tokens and positions
x, _ = self.forward_embedding(prev_output_tokens, token_embeddings, incremental_state)
# relative position
self_attn_rel_pos_bias = None
slen = prev_output_tokens.size(1)
if self.self_attn_relative_position is not None:
self_attn_rel_pos_bias = self.self_attn_relative_position(batch_size=x.size(0), qlen=slen, klen=slen)
if incremental_state is not None:
self_attn_rel_pos_bias = self_attn_rel_pos_bias[-1:, :, :]
cross_attn_rel_pos_bias = None
if self.cross_attn_relative_position is not None:
cross_attn_rel_pos_bias = self.cross_attn_relative_position(
batch_size=x.size(0),
qlen=slen,
klen=encoder_out["encoder_out"].size(1),
)
if incremental_state is not None:
cross_attn_rel_pos_bias = cross_attn_rel_pos_bias[-1:, :, :]
# decoder layers
inner_states = [x]
if encoder_out is None:
l_aux = []
else:
l_aux = encoder_out["l_aux"] if "l_aux" in encoder_out else []
for idx, layer in enumerate(self.layers):
if incremental_state is None:
self_attn_mask = torch.triu(
torch.zeros([x.size(1), x.size(1)]).float().fill_(float("-inf")).type_as(x),
1,
)
else:
self_attn_mask = None
if idx not in incremental_state:
incremental_state[idx] = {}
x, layer_attn, _, l_aux_i = layer(
x,
encoder_out["encoder_out"] if encoder_out is not None else None,
encoder_out["encoder_padding_mask"] if encoder_out is not None else None,
incremental_state[idx] if incremental_state is not None else None,
self_attn_mask=self_attn_mask,
self_attn_padding_mask=self_attn_padding_mask,
self_attn_rel_pos=self_attn_rel_pos_bias,
cross_attn_rel_pos=cross_attn_rel_pos_bias,
)
l_aux.append(l_aux_i)
inner_states.append(x)
if self.layer_norm is not None:
x = self.layer_norm(x)
if not features_only:
x = self.output_layer(x)
return x, {
"inner_states": inner_states,
"l_aux": l_aux,
"attn": None,
}
def output_layer(self, features):
return self.output_projection(features)
|