blt/bytelatent/entropy_model.py
2025-06-06 11:14:55 -07:00

48 lines
1.5 KiB
Python

# Copyright (c) Meta Platforms, Inc. and affiliates.
import json
import logging
import os
import torch
from bytelatent.transformer import LMTransformer, LMTransformerArgs
logger = logging.getLogger()
def load_entropy_model(
entropy_model_checkpoint_dir, state_dict_path, device="cpu", dtype="bf16"
):
with open(os.path.join(entropy_model_checkpoint_dir, "params.json")) as fr:
reloaded = json.loads(fr.read())
# torch.set_default_dtype(dtype)
model_params = reloaded["entropy_model"]
logger.warning(
"Update checkpoint to load attn and sliding window args from checkpoint"
)
entropy_model_args = LMTransformerArgs(
dim=model_params["dim"],
n_layers=model_params["n_layers"],
n_heads=model_params["n_heads"],
max_seqlen=model_params["max_seqlen"],
ffn_dim_multiplier=model_params["ffn_dim_multiplier"],
vocab_size=model_params["vocab_size"],
attn_bias_type="local_block_causal",
attn_impl="xformers",
sliding_window=512,
init_device=device,
init_dtype=dtype,
)
entropy_model = LMTransformer(entropy_model_args)
entropy_model.load_state_dict(
torch.load(state_dict_path, map_location=device)["model"], strict=False
)
entropy_model.to(device)
entropy_model = entropy_model.eval()
# no grads for the model:
for n, param in entropy_model.named_parameters():
param.requires_grad = False
return entropy_model, entropy_model_args