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add noisy mean initialization #1815

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Former-commit-id: a66186b8724ffd0351a32593ab52d8a2312f339b
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hiyouga 2023-12-16 19:47:51 +08:00
parent 4e75ca1222
commit 7c362509a6
1 changed files with 13 additions and 0 deletions
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13
src/llmtuner/model/utils.py
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@ -1,3 +1,4 @@
import math
import torch
from typing import TYPE_CHECKING, Any, Dict, List, Optional, Set, Tuple
@ -124,6 +125,14 @@ def load_valuehead_params(model_args: "ModelArguments") -> Dict[str, torch.Tenso
return None
def noisy_mean_initialization(embed_weight: torch.Tensor, num_new_tokens: int):
embedding_dim = embed_weight.size(1)
avg_weight = embed_weight[:-num_new_tokens].mean(dim=0, keepdim=True)
noise_weight = torch.empty_like(avg_weight[-num_new_tokens:])
noise_weight.normal_(mean=0, std=(1.0 / math.sqrt(embedding_dim)))
embed_weight[-num_new_tokens:] = avg_weight + noise_weight
def prepare_model_for_training(
model: "PreTrainedModel",
finetuning_args: "FinetuningArguments",
@ -181,6 +190,10 @@ def resize_embedding_layer(model: "PreTrainedModel", tokenizer: "PreTrainedToken
model.resize_token_embeddings(len(tokenizer), pad_to_multiple_of=64)
new_embedding_size = model.get_input_embeddings().weight.size(0)
num_new_tokens = new_embedding_size - current_embedding_size
noisy_mean_initialization(model.get_input_embeddings().weight.data, num_new_tokens)
noisy_mean_initialization(model.get_output_embeddings().weight.data, num_new_tokens)
logger.info("Resized token embeddings from {} to {}.".format(current_embedding_size, new_embedding_size))