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Original file line number | Diff line number | Diff line change |
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from __future__ import annotations | ||
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import os | ||
import math | ||
import json | ||
from dataclasses import dataclass | ||
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import torch | ||
import torch.nn as nn | ||
import torch.nn.functional as F | ||
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from torch import Tensor | ||
from safetensors import safe_open | ||
from ohara.utils.load import download_hf_model | ||
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from tqdm import tqdm | ||
from typing import Tuple | ||
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from ohara.modules.mlp import GEGLU | ||
from ohara.modules.norm import RMSNorm | ||
from ohara.embedings_pos.rotatry import precompute_freqs_cis | ||
from ohara.embedings_pos.rotatry import apply_rope | ||
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@dataclass | ||
class GemmaConfig: | ||
vocab_size: int = 51200 | ||
seq_len: int = 2048 | ||
d_model: int = 2048 | ||
intermediate_size = 16 * 2048 | ||
num_heads: int = 32 | ||
num_kv_heads: int = 1 | ||
num_layers: int = 32 | ||
dropout: float = 0.2 | ||
multiple_of: int = 4 | ||
bias: bool = True | ||
eps: float = 1e-5 | ||
rotary_dim: float = 0.4 | ||
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class GemmaAttention(nn.Module): | ||
def __init__( | ||
self, | ||
d_model: int, | ||
num_heads: int, | ||
num_kv_heads: int, | ||
): | ||
super().__init__() | ||
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self.num_heads = num_heads | ||
self.num_kv_heads = num_kv_heads | ||
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assert self.num_heads % self.num_kv_heads == 0 | ||
self.num_queries_per_kv = self.num_heads // self.num_kv_heads | ||
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self.d_model = d_model | ||
self.head_dim = self.d_model // num_heads | ||
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self.q_size = self.num_heads * self.head_dim | ||
self.kv_size = self.num_kv_heads * self.head_dim | ||
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self.scaling:float = self.head_dim**-0.5 | ||
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self.qkv_proj = nn.Linear( | ||
self.d_model, (self.num_heads + 2 * self.num_kv_heads) * self.head_dim | ||
) | ||
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self.o_proj = nn.Linear(self.num_heads * self.head_dim, self.d_model) | ||
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def forward( | ||
self, | ||
x: torch.Tensor, | ||
freqs_cis: torch.Tensor, | ||
mask: torch.Tensor = None, | ||
) -> torch.Tensor: | ||
input_shape = x.shape | ||
assert len(input_shape) == 3 | ||
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batch_size, seq_len, d_model = x.shape | ||
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qkv: Tensor = self.qkv_proj(x) | ||
q, k, v = qkv.split([self.q_size, self.kv_size, self.kv_size], dim=-1) | ||
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q: Tensor = q.view(batch_size, -1, self.num_heads, self.head_dim) | ||
k: Tensor = k.view(batch_size, -1, self.num_kv_heads, self.head_dim) | ||
v: Tensor = v.view(batch_size, -1, self.num_kv_heads, self.head_dim) | ||
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# Positional embedding. | ||
q = apply_rope(q, freqs_cis=freqs_cis) | ||
k = apply_rope(k, freqs_cis=freqs_cis) | ||
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# TODO: add code for kv chache | ||
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# Grouped Query Attention | ||
if self.num_kv_heads != self.num_heads: | ||
key = torch.repeat_interleave(key, self.num_queries_per_kv, dim=2) | ||
value = torch.repeat_interleave(value, self.num_queries_per_kv, dim=2) | ||
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q = q.transpose(1, 2) | ||
k = key.transpose(1, 2) | ||
v = value.transpose(1, 2) | ||
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attn_mtx = torch.matmul(q, k.transpose(2, 3)) * self.scaling | ||
attn_mtx = attn_mtx + mask | ||
attn_mtx = F.softmax(attn_mtx.float(), dim=-1).type_as(q) | ||
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output = torch.matmul(attn_mtx, v) | ||
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output = output.transpose(1, 2).contiguous().view(batch_size, seq_len, -1) | ||
output = self.o_proj(output) | ||
return output | ||
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class Block(nn.Module): | ||
def __init__( | ||
self, | ||
config: GemmaConfig, | ||
): | ||
super().__init__() | ||
self.self_attn = GemmaAttention( | ||
d_model=config.d_model, | ||
num_heads=config.num_heads, | ||
num_kv_heads=config.num_kv_heads, | ||
) | ||
self.mlp = GEGLU( | ||
dim=config.d_model, | ||
hidden_dim=config.intermediate_size, | ||
) | ||
self.ln1 = RMSNorm(config.d_model, eps=config.eps) | ||
self.ln2 = RMSNorm(config.d_model, eps=config.eps) | ||
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def forward( | ||
self, | ||
x: torch.Tensor, | ||
freqs_cis: torch.Tensor, | ||
mask: torch.Tensor, | ||
) -> torch.Tensor: | ||
x = x + self.self_attn(x=self.ln1(x), freqs_cis=freqs_cis, mask=mask) | ||
x = x + self.mlp(self.ln2(x)) | ||
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return x | ||
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class Gemma(nn.Module): | ||
def __init__(self, model_args: GemmaConfig, *args, **kwargs) -> None: | ||
super().__init__(*args, **kwargs) | ||
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self.config = model_args | ||
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self.token_emb = nn.Embedding(model_args.vocab_size, model_args.d_model) | ||
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self.layers = nn.ModuleList( | ||
[Block(model_args) for _ in range(model_args.num_layers)] | ||
) | ||
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self.norm = nn.LayerNorm(model_args.d_model) | ||
self.vocab_proj = nn.Linear( | ||
model_args.d_model, model_args.vocab_size, bias=False | ||
) | ||
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self.token_emb.weight = self.vocab_proj.weight | ||
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self.cos,self.sin = precompute_freqs_cis( | ||
model_args.d_model // model_args.num_heads, model_args.seq_len * 2 | ||
) | ||
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if hasattr(torch.nn.functional, "scaled_dot_product_attention"): | ||
print("WARNING: using slow attention | upgrade pytorch to 2.0 or above") | ||
mask = torch.full( | ||
(1, 1, model_args.seq_len, model_args.seq_len), float("-inf") | ||
) | ||
mask = torch.triu(mask, diagonal=1) | ||
self.register_buffer("mask", mask) | ||
else: | ||
self.mask = None | ||
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def forward(self, x: torch.Tensor): | ||
batch, seqlen = x.shape | ||
x = self.token_emb(x) | ||
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device = self.token_emb.weight.device | ||
freqs_cis = self.cos[:seqlen].to(device), self.sin[:seqlen].to(device) | ||
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for layer in self.layers: | ||
x = layer(x, self.mask, freqs_cis) | ||
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x = self.norm(x) | ||
x = self.vocab_proj(x) | ||
return x |
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