Add Gemma2 (#592)
This commit is contained in:
Ying Sheng
427
python/sglang/srt/models/gemma2.py
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427
python/sglang/srt/models/gemma2.py
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# Adapted from:
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# https://github.com/vllm-project/vllm/blob/56b325e977435af744f8b3dca7af0ca209663558/vllm/model_executor/models/gemma2.py
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from typing import Iterable, List, Optional, Set, Tuple, Union
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import torch
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from torch import nn
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from transformers import Gemma2Config
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from vllm.config import CacheConfig, LoRAConfig
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from vllm.distributed import get_tensor_model_parallel_world_size
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from vllm.model_executor.layers.activation import GeluAndMul
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# from vllm.model_executor.layers.layernorm import GemmaRMSNorm
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from vllm.model_executor.layers.linear import (MergedColumnParallelLinear,
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QKVParallelLinear,
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RowParallelLinear)
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from vllm.model_executor.layers.quantization.base_config import (
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QuantizationConfig)
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# from vllm.model_executor.layers.rotary_embedding import GemmaRotaryEmbedding
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from vllm.model_executor.layers.vocab_parallel_embedding import (
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VocabParallelEmbedding)
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from vllm.model_executor.model_loader.weight_utils import default_weight_loader
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from vllm.model_executor.sampling_metadata import SamplingMetadata
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from sglang.srt.layers.logits_processor import LogitsProcessor
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from sglang.srt.layers.radix_attention import RadixAttention
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from sglang.srt.managers.controller.model_runner import InputMetadata
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# FIXME: temporary solution, remove after next vllm release
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from vllm.model_executor.custom_op import CustomOp
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class GemmaRMSNorm(CustomOp):
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"""RMS normalization for Gemma.
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Two differences from the above RMSNorm:
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1. x * (1 + w) instead of x * w.
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2. (x * w).to(orig_dtype) instead of x.to(orig_dtype) * w.
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"""
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def __init__(
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self,
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hidden_size: int,
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eps: float = 1e-6,
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) -> None:
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super().__init__()
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self.weight = nn.Parameter(torch.zeros(hidden_size))
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self.variance_epsilon = eps
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def forward_native(
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self,
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x: torch.Tensor,
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residual: Optional[torch.Tensor] = None,
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) -> Union[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]]:
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"""PyTorch-native implementation equivalent to forward()."""
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orig_dtype = x.dtype
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if residual is not None:
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x = x + residual
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residual = x
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x = x.float()
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variance = x.pow(2).mean(dim=-1, keepdim=True)
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x = x * torch.rsqrt(variance + self.variance_epsilon)
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# Llama does x.to(float16) * w whilst Gemma is (x * w).to(float16)
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# See https://github.com/huggingface/transformers/pull/29402
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x = x * (1.0 + self.weight.float())
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x = x.to(orig_dtype)
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return x if residual is None else (x, residual)
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def forward_cuda(
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self,
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x: torch.Tensor,
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residual: Optional[torch.Tensor] = None,
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) -> Union[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]]:
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# from vLLM: TODO(woosuk): Implement an optimized kernel for GemmaRMSNorm.
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return self.forward_native(x, residual)
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# FIXME: temporary solution, remove after next vllm release
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from vllm.model_executor.layers.rotary_embedding import RotaryEmbedding
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class GemmaRotaryEmbedding(RotaryEmbedding):
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def _compute_inv_freq(self, base: Union[int, float]) -> torch.Tensor:
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# https://github.com/huggingface/transformers/blob/v4.41.2/src/transformers/models/gemma/modeling_gemma.py#L107
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inv_freq = 1.0 / (base**(
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torch.arange(0, self.rotary_dim, 2, dtype=torch.int64).float() /
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self.rotary_dim))
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return inv_freq
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class Gemma2MLP(nn.Module):
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def __init__(
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self,
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hidden_size: int,
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intermediate_size: int,
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hidden_act: str,
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hidden_activation: str,
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quant_config: Optional[QuantizationConfig] = None,
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) -> None:
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super().__init__()
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self.gate_up_proj = MergedColumnParallelLinear(
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hidden_size, [intermediate_size] * 2,
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bias=False,
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quant_config=quant_config)
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self.down_proj = RowParallelLinear(intermediate_size,
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hidden_size,
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bias=False,
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quant_config=quant_config)
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if not (hidden_act == hidden_activation == "gelu_pytorch_tanh"):
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raise ValueError(
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"Gemma2 uses `gelu_pytorch_tanh` as the hidden activation "
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"function. Please set `hidden_act` and `hidden_activation` to "
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"`gelu_pytorch_tanh`.")
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self.act_fn = GeluAndMul(approximate="tanh")
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def forward(self, x: torch.Tensor) -> torch.Tensor:
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gate_up, _ = self.gate_up_proj(x)
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x = self.act_fn(gate_up)
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x, _ = self.down_proj(x)
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return x
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class Gemma2Attention(nn.Module):
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def __init__(self,
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layer_idx: int,
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config: Gemma2Config,
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hidden_size: int,
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num_heads: int,
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num_kv_heads: int,
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head_dim: int,
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max_position_embeddings: int,
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rope_theta: float,
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cache_config: Optional[CacheConfig] = None,
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quant_config: Optional[QuantizationConfig] = None) -> None:
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super().__init__()
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self.layer_idx = layer_idx
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self.config = config
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self.hidden_size = hidden_size
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tp_size = get_tensor_model_parallel_world_size()
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self.total_num_heads = num_heads
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assert self.total_num_heads % tp_size == 0
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self.num_heads = self.total_num_heads // tp_size
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self.total_num_kv_heads = num_kv_heads
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if self.total_num_kv_heads >= tp_size:
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# Number of KV heads is greater than TP size, so we partition
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# the KV heads across multiple tensor parallel GPUs.
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assert self.total_num_kv_heads % tp_size == 0
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else:
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# Number of KV heads is less than TP size, so we replicate
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# the KV heads across multiple tensor parallel GPUs.
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assert tp_size % self.total_num_kv_heads == 0
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self.num_kv_heads = max(1, self.total_num_kv_heads // tp_size)
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self.head_dim = head_dim
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self.q_size = self.num_heads * self.head_dim
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self.kv_size = self.num_kv_heads * self.head_dim
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self.scaling = config.query_pre_attn_scalar**-0.5
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self.rope_theta = rope_theta
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self.qkv_proj = QKVParallelLinear(
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hidden_size,
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self.head_dim,
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self.total_num_heads,
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self.total_num_kv_heads,
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bias=config.attention_bias,
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quant_config=quant_config,
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)
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self.o_proj = RowParallelLinear(
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self.total_num_heads * self.head_dim,
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hidden_size,
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bias=config.attention_bias,
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quant_config=quant_config,
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)
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# from vLLM: TODO(woosuk): Use the `get_rope` interface.
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self.rotary_emb = GemmaRotaryEmbedding(
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self.head_dim,
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self.head_dim,
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max_position_embeddings,
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base=self.rope_theta,
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is_neox_style=True,
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dtype=torch.get_default_dtype(),
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)
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# from vLLM: FIXME(woosuk): While Gemma 2 uses sliding window attention for every
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# odd layer, vLLM currently ignores it and uses global attention for
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# all layers.
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use_sliding_window = (layer_idx % 2 == 1
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and config.sliding_window is not None)
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del use_sliding_window # Unused.
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self.attn = RadixAttention(self.num_heads,
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self.head_dim,
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self.scaling,
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num_kv_heads=self.num_kv_heads,
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layer_id=layer_idx,
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logit_cap=self.config.attn_logit_softcapping)
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def forward(
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self,
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positions: torch.Tensor,
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hidden_states: torch.Tensor,
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input_metadata: InputMetadata,
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) -> torch.Tensor:
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qkv, _ = self.qkv_proj(hidden_states)
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q, k, v = qkv.split([self.q_size, self.kv_size, self.kv_size], dim=-1)
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q, k = self.rotary_emb(positions, q, k)
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attn_output = self.attn(q, k, v, input_metadata)
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output, _ = self.o_proj(attn_output)
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return output
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class Gemma2DecoderLayer(nn.Module):
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def __init__(
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self,
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layer_idx: int,
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config: Gemma2Config,
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cache_config: Optional[CacheConfig] = None,
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quant_config: Optional[QuantizationConfig] = None,
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) -> None:
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super().__init__()
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self.hidden_size = config.hidden_size
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self.self_attn = Gemma2Attention(
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layer_idx=layer_idx,
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config=config,
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hidden_size=self.hidden_size,
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num_heads=config.num_attention_heads,
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num_kv_heads=config.num_key_value_heads,
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head_dim=config.head_dim,
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max_position_embeddings=config.max_position_embeddings,
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rope_theta=config.rope_theta,
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cache_config=cache_config,
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quant_config=quant_config,
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)
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self.hidden_size = config.hidden_size
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self.mlp = Gemma2MLP(
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hidden_size=self.hidden_size,
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intermediate_size=config.intermediate_size,
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hidden_act=config.hidden_act,
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hidden_activation=config.hidden_activation,
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quant_config=quant_config,
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)
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self.input_layernorm = GemmaRMSNorm(config.hidden_size,
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eps=config.rms_norm_eps)
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self.post_attention_layernorm = GemmaRMSNorm(config.hidden_size,
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eps=config.rms_norm_eps)
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self.pre_feedforward_layernorm = GemmaRMSNorm(config.hidden_size,
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eps=config.rms_norm_eps)
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self.post_feedforward_layernorm = GemmaRMSNorm(config.hidden_size,
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eps=config.rms_norm_eps)
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def forward(
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self,
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positions: torch.Tensor,
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hidden_states: torch.Tensor,
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input_metadata: InputMetadata,
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residual: Optional[torch.Tensor],
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) -> Tuple[torch.Tensor, torch.Tensor]:
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if residual is None:
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residual = hidden_states
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hidden_states = self.input_layernorm(hidden_states)
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else:
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hidden_states, residual = self.input_layernorm(
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hidden_states, residual)
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hidden_states = self.self_attn(
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positions=positions,
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hidden_states=hidden_states,
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input_metadata=input_metadata,
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)
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hidden_states = self.post_attention_layernorm(hidden_states)
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hidden_states, residual = self.pre_feedforward_layernorm(
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hidden_states, residual)
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hidden_states = self.mlp(hidden_states)
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hidden_states = self.post_feedforward_layernorm(hidden_states)
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return hidden_states, residual
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class Gemma2Model(nn.Module):
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def __init__(
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self,
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config: Gemma2Config,
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cache_config: Optional[CacheConfig] = None,
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quant_config: Optional[QuantizationConfig] = None,
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) -> None:
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super().__init__()
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self.config = config
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self.embed_tokens = VocabParallelEmbedding(
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config.vocab_size,
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config.hidden_size,
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)
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self.layers = nn.ModuleList([
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Gemma2DecoderLayer(layer_idx, config, cache_config, quant_config)
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for layer_idx in range(config.num_hidden_layers)
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])
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self.norm = GemmaRMSNorm(config.hidden_size, eps=config.rms_norm_eps)
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# Normalize the embedding by sqrt(hidden_size)
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# The normalizer's data type should be downcasted to the model's
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# data type such as bfloat16, not float32.
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# See https://github.com/huggingface/transformers/pull/29402
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normalizer = self.config.hidden_size**0.5
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self.register_buffer("normalizer", torch.tensor(normalizer))
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def forward(
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self,
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input_ids: torch.Tensor,
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positions: torch.Tensor,
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input_metadata: InputMetadata,
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input_embeds: torch.Tensor = None,
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) -> torch.Tensor:
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if input_embeds is None:
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hidden_states = self.embed_tokens(input_ids)
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else:
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hidden_states = input_embeds
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normalizer = torch.tensor(self.config.hidden_size**0.5, dtype=torch.float16)
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hidden_states *= normalizer
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residual = None
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for i in range(len(self.layers)):
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layer = self.layers[i]
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hidden_states, residual = layer(
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positions,
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hidden_states,
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input_metadata,
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residual,
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)
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hidden_states, _ = self.norm(hidden_states, residual)
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return hidden_states
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class Gemma2ForCausalLM(nn.Module):
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packed_modules_mapping = {
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"qkv_proj": [
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"q_proj",
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"k_proj",
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"v_proj",
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],
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"gate_up_proj": [
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"gate_proj",
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"up_proj",
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],
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}
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# LoRA specific attributes
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supported_lora_modules = [
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"qkv_proj",
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"o_proj",
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"gate_up_proj",
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"down_proj",
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]
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# Gemma does not apply LoRA to the embedding layer.
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embedding_modules = {}
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embedding_padding_modules = []
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def __init__(
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self,
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config: Gemma2Config,
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cache_config: Optional[CacheConfig] = None,
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quant_config: Optional[QuantizationConfig] = None,
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lora_config: Optional[LoRAConfig] = None,
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) -> None:
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del lora_config # Unused.
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super().__init__()
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self.config = config
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self.quant_config = quant_config
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self.model = Gemma2Model(config, cache_config, quant_config)
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self.logits_processor = LogitsProcessor(config)
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@torch.no_grad()
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def forward(
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self,
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input_ids: torch.Tensor,
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positions: torch.Tensor,
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input_metadata: InputMetadata,
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input_embeds: torch.Tensor = None,
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) -> torch.Tensor:
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hidden_states = self.model(input_ids, positions, input_metadata, input_embeds)
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return self.logits_processor(
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input_ids, hidden_states, self.model.embed_tokens.weight, input_metadata
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)
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def load_weights(self, weights: Iterable[Tuple[str, torch.Tensor]]):
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stacked_params_mapping = [
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# (param_name, shard_name, shard_id)
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("qkv_proj", "q_proj", "q"),
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("qkv_proj", "k_proj", "k"),
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("qkv_proj", "v_proj", "v"),
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("gate_up_proj", "gate_proj", 0),
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("gate_up_proj", "up_proj", 1),
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]
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params_dict = dict(self.named_parameters())
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loaded_params: Set[str] = set()
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for name, loaded_weight in weights:
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for (param_name, shard_name, shard_id) in stacked_params_mapping:
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if shard_name not in name:
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continue
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name = name.replace(shard_name, param_name)
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# Skip loading extra bias for GPTQ models.
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if name.endswith(".bias") and name not in params_dict:
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continue
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param = params_dict[name]
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weight_loader = param.weight_loader
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weight_loader(param, loaded_weight, shard_id)
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break
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else:
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# lm_head is not used in vllm as it is tied with embed_token.
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# To prevent errors, skip loading lm_head.weight.
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if "lm_head.weight" in name:
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continue
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# Skip loading extra bias for GPTQ models.
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if name.endswith(".bias") and name not in params_dict:
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continue
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param = params_dict[name]
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weight_loader = getattr(param, "weight_loader",
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default_weight_loader)
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weight_loader(param, loaded_weight)
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loaded_params.add(name)
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unloaded_params = params_dict.keys() - loaded_params
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if unloaded_params:
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raise RuntimeError(
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"Some weights are not initialized from checkpoints: "
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f"{unloaded_params}")
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EntryClass = Gemma2ForCausalLM
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