mirror of
https://github.com/rasbt/LLMs-from-scratch.git
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114 lines
3.7 KiB
Python
114 lines
3.7 KiB
Python
# Copyright (c) Sebastian Raschka under Apache License 2.0 (see LICENSE.txt).
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# Source for "Build a Large Language Model From Scratch"
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# - https://www.manning.com/books/build-a-large-language-model-from-scratch
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# Code: https://github.com/rasbt/LLMs-from-scratch
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import importlib
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from pathlib import Path
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import pytest
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import torch
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from llms_from_scratch.utils import import_definitions_from_notebook
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transformers_installed = importlib.util.find_spec("transformers") is not None
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@pytest.fixture
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def nb_imports():
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nb_dir = Path(__file__).resolve().parents[1]
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mod = import_definitions_from_notebook(nb_dir, "standalone-gemma3-plus-kvcache.ipynb")
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return mod
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@pytest.fixture
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def dummy_input():
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torch.manual_seed(123)
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return torch.randint(0, 100, (1, 8)) # batch size 1, seq length 8
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@pytest.fixture
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def dummy_cfg_base():
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return {
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"vocab_size": 100,
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"emb_dim": 32,
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"hidden_dim": 64,
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"n_layers": 2,
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"n_heads": 4,
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"head_dim": 8,
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"n_kv_groups": 1,
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"qk_norm": True, # Gemma3 uses q/k RMSNorm
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"dtype": torch.float32,
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"rope_base": 1_000_000.0, # global RoPE base
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"rope_local_base": 10_000.0, # local RoPE base (unused in these tests)
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"context_length": 64,
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"sliding_window": 16,
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"layer_types": ["full_attention", "full_attention"],
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"query_pre_attn_scalar": 256,
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}
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@torch.inference_mode()
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def test_dummy_gemma3_forward(dummy_cfg_base, dummy_input, nb_imports):
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torch.manual_seed(123)
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model = nb_imports.Gemma3Model(dummy_cfg_base)
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out = model(dummy_input)
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assert out.shape == (1, dummy_input.size(1), dummy_cfg_base["vocab_size"])
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@torch.inference_mode()
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@pytest.mark.skipif(not transformers_installed, reason="transformers not installed")
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def test_gemma3_base_equivalence_with_transformers(nb_imports):
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from transformers import Gemma3TextConfig, Gemma3ForCausalLM
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# Tiny config so the test is fast
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cfg = {
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"vocab_size": 257,
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"context_length": 8,
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"emb_dim": 32,
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"n_heads": 4,
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"n_layers": 2,
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"hidden_dim": 64,
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"head_dim": 8,
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"qk_norm": True,
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"n_kv_groups": 2,
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"rope_base": 1_000_000.0,
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"rope_local_base": 10_000.0,
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"sliding_window": 4,
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"layer_types": ["full_attention", "full_attention"],
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"dtype": torch.float32,
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"query_pre_attn_scalar": 256,
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}
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model = nb_imports.Gemma3Model(cfg)
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hf_cfg = Gemma3TextConfig(
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vocab_size=cfg["vocab_size"],
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max_position_embeddings=cfg["context_length"],
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hidden_size=cfg["emb_dim"],
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num_attention_heads=cfg["n_heads"],
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num_hidden_layers=cfg["n_layers"],
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intermediate_size=cfg["hidden_dim"],
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head_dim=cfg["head_dim"],
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num_key_value_heads=cfg["n_kv_groups"],
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rope_theta=cfg["rope_base"],
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rope_local_base_freq=cfg["rope_local_base"],
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layer_types=cfg["layer_types"],
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sliding_window=cfg["sliding_window"],
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tie_word_embeddings=False,
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attn_implementation="eager",
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torch_dtype=torch.float32,
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query_pre_attn_scalar=cfg["query_pre_attn_scalar"],
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rope_scaling={"rope_type": "default"},
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)
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hf_model = Gemma3ForCausalLM(hf_cfg)
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hf_state = hf_model.state_dict()
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param_config = {"n_layers": cfg["n_layers"], "hidden_dim": cfg["hidden_dim"]}
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nb_imports.load_weights_into_gemma(model, param_config, hf_state)
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x = torch.randint(0, cfg["vocab_size"], (2, cfg["context_length"]), dtype=torch.long)
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ours_logits = model(x)
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theirs_logits = hf_model(x).logits
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torch.testing.assert_close(ours_logits, theirs_logits, rtol=1e-5, atol=1e-5)
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