Yu Chengzhang
57d6d768e1
## 实验目标 验证连接方式是否是导致实验1.4.1性能下降的主要原因，通过将跳接（交叉注意力） 改为串型连接（门控MLP融合）来测试记忆库机制的有效性。 ## 核心改进 - 保留Product Key Memory记忆选择机制 - 使用串型连接替代跳接连接 - 门控MLP融合替代交叉注意力 - 拼接h_attn和选中记忆进行处理 ## 实验结果 - 训练Loss: 2.75 (vs 1.4.1的2.84, 1.4.0的2.43) - 评估Loss: 2.33 (vs 1.4.1的7.68, 1.4.0的1.99) - 生成质量: 6.2/10 (vs 1.4.1的2.0/10, 1.4.0的7.5/10) - 训练时间: 15.4小时，GPU内存: ~22GB ## 关键发现 ✅ 连接方式确实是性能差异的关键因素 ✅ 门控MLP融合显著优于交叉注意力 ✅ 记忆库机制本身可行，但需要优化记忆质量 ## 技术实现 - 实现GatedMemoryFusion类替代CrossAttentionMemory - 使用类SwiGLU的门控MLP结构 - 拼接输入维度: dim + num_selected * knowledge_dim - 门控激活函数: SiLU + 元素级乘法 ## 文件变更 - model/model_memory.py: 实现门控MLP融合机制 - run_file/experiment_1_4_2.sh: 实验执行脚本 - experiment/EXPERIMENT_1_4_2.md: 完整实验记录和分析 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
393 lines
17 KiB
Python
393 lines
17 KiB
Python
import math
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import struct
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import inspect
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import time
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from .LMConfig import LMConfig
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from typing import Any, Optional, Tuple, List, Union
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import numpy as np
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import torch
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import torch.nn.functional as F
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from torch import nn
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from transformers import PreTrainedModel
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from transformers.modeling_outputs import CausalLMOutputWithPast
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class RMSNorm(torch.nn.Module):
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def __init__(self, dim: int, eps: float = 1e-6):
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super().__init__()
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self.eps = eps
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self.weight = nn.Parameter(torch.ones(dim))
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def _norm(self, x):
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return x * torch.rsqrt(x.pow(2).mean(-1, keepdim=True) + self.eps)
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def forward(self, x):
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return self.weight * self._norm(x.float()).type_as(x)
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def precompute_pos_cis(dim: int, end: int = int(32 * 1024), theta: float = 1e6):
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freqs = 1.0 / (theta ** (torch.arange(0, dim, 2)[: (dim // 2)].float() / dim))
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t = torch.arange(end, device=freqs.device) # type: ignore
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freqs = torch.outer(t, freqs).float() # type: ignore
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pos_cis = torch.polar(torch.ones_like(freqs), freqs) # complex64
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return pos_cis
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def apply_rotary_emb(xq, xk, pos_cis):
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def unite_shape(pos_cis, x):
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ndim = x.ndim
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assert 0 <= 1 < ndim
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assert pos_cis.shape == (x.shape[1], x.shape[-1])
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shape = [d if i == 1 or i == ndim - 1 else 1 for i, d in enumerate(x.shape)]
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return pos_cis.view(*shape)
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xq_ = torch.view_as_complex(xq.float().reshape(*xq.shape[:-1], -1, 2))
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xk_ = torch.view_as_complex(xk.float().reshape(*xk.shape[:-1], -1, 2))
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pos_cis = unite_shape(pos_cis, xq_)
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xq_out = torch.view_as_real(xq_ * pos_cis).flatten(3)
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xk_out = torch.view_as_real(xk_ * pos_cis).flatten(3)
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return xq_out.type_as(xq), xk_out.type_as(xk)
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def repeat_kv(x: torch.Tensor, n_rep: int) -> torch.Tensor:
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"""torch.repeat_interleave(x, dim=2, repeats=n_rep)"""
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bs, slen, n_kv_heads, head_dim = x.shape
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if n_rep == 1:
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return x
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return (
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x[:, :, :, None, :]
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.expand(bs, slen, n_kv_heads, n_rep, head_dim)
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.reshape(bs, slen, n_kv_heads * n_rep, head_dim)
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)
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class Attention(nn.Module):
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"""Self attention module without KV cache"""
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def __init__(self, args: LMConfig):
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super().__init__()
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self.n_kv_heads = args.n_heads if args.n_kv_heads is None else args.n_kv_heads
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assert args.n_heads % self.n_kv_heads == 0
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self.n_local_heads = args.n_heads
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self.n_local_kv_heads = self.n_kv_heads
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self.n_rep = self.n_local_heads // self.n_local_kv_heads
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self.head_dim = args.dim // args.n_heads
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self.wq = nn.Linear(args.dim, args.n_heads * self.head_dim, bias=False)
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self.wk = nn.Linear(args.dim, self.n_kv_heads * self.head_dim, bias=False)
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self.wv = nn.Linear(args.dim, self.n_kv_heads * self.head_dim, bias=False)
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self.wo = nn.Linear(args.n_heads * self.head_dim, args.dim, bias=False)
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self.attn_dropout = nn.Dropout(args.dropout)
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self.resid_dropout = nn.Dropout(args.dropout)
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self.dropout = args.dropout
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self.flash = hasattr(torch.nn.functional, 'scaled_dot_product_attention') and args.flash_attn
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# print("WARNING: using slow attention. Flash Attention requires PyTorch >= 2.0")
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mask = torch.full((1, 1, args.max_seq_len, args.max_seq_len), float("-inf"))
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mask = torch.triu(mask, diagonal=1)
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self.register_buffer("mask", mask, persistent=False)
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def forward(self, x: torch.Tensor, pos_cis: torch.Tensor):
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"""Forward pass without KV cache"""
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bsz, seq_len, _ = x.shape
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xq, xk, xv = self.wq(x), self.wk(x), self.wv(x)
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xq = xq.view(bsz, seq_len, self.n_local_heads, self.head_dim)
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xk = xk.view(bsz, seq_len, self.n_local_kv_heads, self.head_dim)
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xv = xv.view(bsz, seq_len, self.n_local_kv_heads, self.head_dim)
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xq, xk = apply_rotary_emb(xq, xk, pos_cis)
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# 注意：完全去除了KV cache相关代码
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xq, xk, xv = (
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xq.transpose(1, 2),
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repeat_kv(xk, self.n_rep).transpose(1, 2),
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repeat_kv(xv, self.n_rep).transpose(1, 2)
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)
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if self.flash and seq_len != 1:
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dropout_p = self.dropout if self.training else 0.0
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output = F.scaled_dot_product_attention(
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xq, xk, xv,
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attn_mask=None,
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dropout_p=dropout_p,
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is_causal=True
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)
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else:
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scores = (xq @ xk.transpose(-2, -1)) / math.sqrt(self.head_dim)
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scores += self.mask[:, :, :seq_len, :seq_len]
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scores = F.softmax(scores.float(), dim=-1).type_as(xq)
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scores = self.attn_dropout(scores)
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output = scores @ xv
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output = output.transpose(1, 2).reshape(bsz, seq_len, -1)
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output = self.resid_dropout(self.wo(output))
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return output
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class MemoryGate(nn.Module):
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"""Product Key Memory-based gate mechanism for memory selection"""
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def __init__(self, config: LMConfig):
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super().__init__()
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self.config = config
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self.dim = config.dim
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self.knowledge_num = config.knowledge_num
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self.knowledge_dim = config.knowledge_dim
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self.num_selected = getattr(config, 'num_selected', 16)
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# 确保知识库数量是完全平方数
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assert int(self.knowledge_num ** 0.5) ** 2 == self.knowledge_num, \
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f"knowledge_num ({self.knowledge_num}) must be a perfect square for product key memory"
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self.num_keys = int(self.knowledge_num ** 0.5)
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# 查询投影：将输入维度映射到knowledge_dim * 2（用于两个product key）
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self.gate_proj = nn.Linear(self.dim, self.knowledge_dim, bias=False)
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# Product Key Memory: 两个独立的键集合
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self.keys = nn.Parameter(torch.randn(2, self.num_keys, self.knowledge_dim // 2))
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self.dropout = nn.Dropout(config.dropout)
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def forward(self, x: torch.Tensor):
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"""
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Args:
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x: [batch_size, seq_len, dim]
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Returns:
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memory_indices: [batch_size, seq_len, num_selected]
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memory_scores: [batch_size, seq_len, num_selected]
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"""
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bsz, seq_len, _ = x.shape
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# 生成查询向量
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queries = self.gate_proj(x) # [batch, seq_len, knowledge_dim]
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# 分割为两部分用于product key
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q1 = queries[:, :, :self.knowledge_dim // 2] # [batch, seq_len, knowledge_dim // 2]
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q2 = queries[:, :, self.knowledge_dim // 2:] # [batch, seq_len, knowledge_dim // 2]
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# 计算与两个键集合的相似度
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scores_1 = torch.einsum('bsd,kd->bsk', q1, self.keys[0]) # [batch, seq_len, num_keys]
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scores_2 = torch.einsum('bsd,kd->bsk', q2, self.keys[1]) # [batch, seq_len, num_keys]
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# 获取top-k
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topk_scores_1, topk_indices_1 = scores_1.topk(self.num_selected, dim=-1)
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topk_scores_2, topk_indices_2 = scores_2.topk(self.num_selected, dim=-1)
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# 组合product key的结果
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combined_scores = topk_scores_1.unsqueeze(-1) + topk_scores_2.unsqueeze(-2) # [batch, seq_len, num_selected, num_selected]
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combined_indices = topk_indices_1.unsqueeze(-1) * self.num_keys + topk_indices_2.unsqueeze(-2) # [batch, seq_len, num_selected, num_selected]
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# 展平并选择最终的top-k
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combined_scores = combined_scores.view(bsz, seq_len, -1)
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combined_indices = combined_indices.view(bsz, seq_len, -1)
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final_scores, final_pk_indices = combined_scores.topk(self.num_selected, dim=-1)
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memory_indices = combined_indices.gather(-1, final_pk_indices)
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# 归一化分数
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memory_scores = F.softmax(final_scores, dim=-1)
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memory_scores = self.dropout(memory_scores)
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return memory_indices, memory_scores
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class GatedMemoryFusion(nn.Module):
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"""Gated MLP fusion for concatenated h_attn and selected memories"""
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def __init__(self, config: LMConfig):
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super().__init__()
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self.config = config
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self.dim = config.dim
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self.knowledge_dim = config.knowledge_dim
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self.num_selected = getattr(config, 'num_selected', 16)
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# 输入维度：dim (h_attn) + num_selected * knowledge_dim (选中的记忆)
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concat_dim = self.dim + self.num_selected * self.knowledge_dim
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# 类似SwiGLU的门控MLP结构
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self.gate_proj = nn.Linear(concat_dim, self.dim, bias=False)
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self.up_proj = nn.Linear(concat_dim, self.dim, bias=False)
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self.down_proj = nn.Linear(self.dim, self.dim, bias=False)
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self.dropout = nn.Dropout(config.dropout)
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def forward(self, h_attn: torch.Tensor, selected_memories: torch.Tensor, memory_scores: torch.Tensor):
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"""
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Args:
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h_attn: [batch_size, seq_len, dim] - Self attention output
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selected_memories: [batch_size, seq_len, num_selected, knowledge_dim] - Selected memory data
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memory_scores: [batch_size, seq_len, num_selected] - Memory selection weights (not used in concatenation approach)
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Returns:
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output: [batch_size, seq_len, dim]
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"""
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bsz, seq_len, _ = h_attn.shape
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# 将选中的记忆展平为一维向量
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# [batch, seq_len, num_selected, knowledge_dim] -> [batch, seq_len, num_selected * knowledge_dim]
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memory_flat = selected_memories.view(bsz, seq_len, -1)
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# 拼接h_attn和记忆信息
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concat_input = torch.cat([h_attn, memory_flat], dim=-1) # [batch, seq_len, dim + num_selected * knowledge_dim]
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# 门控MLP处理（类似SwiGLU）
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gate = F.silu(self.gate_proj(concat_input)) # [batch, seq_len, dim]
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up = self.up_proj(concat_input) # [batch, seq_len, dim]
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fusion_output = gate * up # Element-wise multiplication
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# 输出投影
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output = self.down_proj(fusion_output) # [batch, seq_len, dim]
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output = self.dropout(output)
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return output
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class MiniMindBlock(nn.Module):
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"""Transformer block with memory-based cross attention instead of FFN"""
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def __init__(self, layer_id: int, config: LMConfig):
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super().__init__()
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self.n_heads = config.n_heads
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self.dim = config.dim
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self.head_dim = config.dim // config.n_heads
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self.attention = Attention(config)
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self.layer_id = layer_id
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self.attention_norm = RMSNorm(config.dim, eps=config.norm_eps)
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self.memory_norm = RMSNorm(config.dim, eps=config.norm_eps)
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# 记忆相关模块
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self.memory_gate = MemoryGate(config)
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self.gated_memory_fusion = GatedMemoryFusion(config)
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def forward(self, x, pos_cis, memory_bank):
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"""
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Args:
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x: [batch_size, seq_len, dim]
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pos_cis: positional encoding
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memory_bank: [knowledge_num, knowledge_dim] - shared memory bank
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"""
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# Self attention
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h_attn = self.attention(self.attention_norm(x), pos_cis)
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h = x + h_attn
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# 使用h_attn作为门控和交叉注意力的输入（核心：self attention的输出）
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h_for_memory = self.memory_norm(h_attn)
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# 门控选择记忆
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memory_indices, memory_scores = self.memory_gate(h_for_memory)
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# 根据索引获取记忆数据
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bsz, seq_len, num_selected = memory_indices.shape
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memory_indices_flat = memory_indices.view(-1)
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selected_memory = memory_bank[memory_indices_flat] # [batch * seq_len * num_selected, knowledge_dim]
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selected_memory = selected_memory.view(bsz, seq_len, num_selected, -1) # [batch, seq_len, num_selected, knowledge_dim]
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# 门控MLP融合：串型连接h_attn和选中的记忆
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memory_output = self.gated_memory_fusion(h_for_memory, selected_memory, memory_scores)
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# 残差连接
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out = h + memory_output
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return out
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class MiniMindLM(PreTrainedModel):
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config_class = LMConfig
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def __init__(self, params: LMConfig = None):
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self.params = params or LMConfig()
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super().__init__(self.params)
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self.vocab_size, self.n_layers = params.vocab_size, params.n_layers
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self.tok_embeddings = nn.Embedding(params.vocab_size, params.dim)
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self.dropout = nn.Dropout(params.dropout)
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self.layers = nn.ModuleList([MiniMindBlock(l, params) for l in range(self.n_layers)])
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self.norm = RMSNorm(params.dim, eps=params.norm_eps)
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self.output = nn.Linear(params.dim, params.vocab_size, bias=False)
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self.tok_embeddings.weight = self.output.weight
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self.register_buffer("pos_cis",
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precompute_pos_cis(dim=params.dim // params.n_heads, theta=params.rope_theta),
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persistent=False)
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# 初始化共享记忆库
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self.memory_bank = nn.Parameter(
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torch.randn(params.knowledge_num, params.knowledge_dim),
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requires_grad=True
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)
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self.OUT = CausalLMOutputWithPast()
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def forward(self,
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input_ids: Optional[torch.Tensor] = None,
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**args):
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"""Forward pass without KV cache support"""
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start_pos = args.get('start_pos', 0)
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h = self.dropout(self.tok_embeddings(input_ids))
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pos_cis = self.pos_cis[start_pos:start_pos + input_ids.size(1)]
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for layer in self.layers:
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h = layer(h, pos_cis, self.memory_bank)
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logits = self.output(self.norm(h))
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# 统一不使用 aux_loss
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aux_loss = 0
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self.OUT.__setitem__('last_hidden_state', h)
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self.OUT.__setitem__('logits', logits)
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self.OUT.__setitem__('aux_loss', aux_loss)
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self.OUT.__setitem__('past_key_values', None) # 不支持KV cache
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return self.OUT
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@torch.inference_mode()
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def generate(self, input_ids, eos_token_id=2, max_new_tokens=1024, temperature=0.75, top_p=0.90,
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stream=False, rp=1., pad_token_id=0, num_return_sequences=1, **args):
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"""Generate without KV cache"""
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# 流式生成
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if stream:
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return self._stream(input_ids, eos_token_id, max_new_tokens, temperature, top_p, rp, **args)
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# 直接生成
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generated = []
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for i in range(input_ids.size(0)):
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non_pad = input_ids[i][input_ids[i] != pad_token_id].unsqueeze(0)
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for _ in range(num_return_sequences):
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out = self._stream(non_pad, eos_token_id, max_new_tokens, temperature, top_p, rp, **args)
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tokens_list = [tokens[:, -1:] for tokens in out]
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gen = torch.cat(tokens_list, dim=-1) if tokens_list else non_pad
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full_sequence = torch.cat([non_pad, gen], dim=-1)
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generated.append(full_sequence)
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max_length = max(seq.size(1) for seq in generated)
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generated = [
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torch.cat(
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[seq, torch.full((1, max_length - seq.size(1)), pad_token_id, dtype=seq.dtype, device=seq.device)],
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dim=-1)
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for seq in generated
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]
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output = torch.cat(generated, dim=0)
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res = output.view(input_ids.size(0) * num_return_sequences, -1)
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return res
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def _stream(self, input_ids, eos_token_id, max_new_tokens, temperature, top_p, rp, **args):
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"""Stream generation without KV cache - regenerates full sequence each time"""
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start = input_ids.shape[1]
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while input_ids.shape[1] < start + max_new_tokens:
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# 每次都重新计算整个序列（因为没有KV cache）
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out = self(input_ids, **args)
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logits = out.logits[:, -1, :]
|
||
|
||
# 重复惩罚
|
||
logits[:, list(set(input_ids.tolist()[0]))] /= rp
|
||
logits /= (temperature + 1e-9)
|
||
|
||
# Top-p采样
|
||
if top_p is not None and top_p < 1.0:
|
||
sorted_logits, sorted_indices = torch.sort(logits, descending=True, dim=-1)
|
||
sorted_probs = F.softmax(sorted_logits, dim=-1)
|
||
cumulative_probs = torch.cumsum(sorted_probs, dim=-1)
|
||
sorted_indices_to_remove = cumulative_probs > top_p
|
||
sorted_indices_to_remove[:, 1:] = sorted_indices_to_remove[:, :-1].clone()
|
||
sorted_indices_to_remove[:, 0] = False
|
||
indices_to_remove = sorted_indices_to_remove.scatter(1, sorted_indices, sorted_indices_to_remove)
|
||
logits[indices_to_remove] = -float('Inf')
|
||
|
||
input_ids_next = torch.multinomial(F.softmax(logits, dim=-1), num_samples=1)
|
||
input_ids = torch.cat((input_ids, input_ids_next), dim=1)
|
||
yield input_ids[:, start:]
|
||
if input_ids_next.item() == eos_token_id:
|
||
break |