text-generation-inference/server/bloom_inference/shard_model.py
Olivier Dehaene 295831a481 Init
2022-10-08 12:30:12 +02:00

103 lines
3.7 KiB
Python

from pathlib import Path
import torch
from torch import nn
from transformers import AutoModelForCausalLM
def match_suffix(text, suffix):
return text[-len(suffix) :] == suffix
def shard_model(model_name: str, path: Path, tp_world_size: int, dtype: torch.dtype):
"""BLOOM specific sharding mechanism"""
save_paths = [
path / f"{model_name}_tp-rank-{tp_rank}-of-{tp_world_size}.pty"
for tp_rank in range(tp_world_size)
]
if all(save_path.exists() for save_path in save_paths):
print("Loading already cached values")
return save_paths
model: nn.Module = AutoModelForCausalLM.from_pretrained(
model_name, torch_dtype=dtype, local_files_only=True
)
shards_state_dicts = [{} for _ in range(tp_world_size)]
state_dict = model.state_dict()
keys = list(state_dict.keys())
for state_name in keys:
print(state_name)
state = state_dict[state_name]
if any(
match_suffix(state_name, candidate)
for candidate in [
"self_attention.query_key_value.weight",
"self_attention.query_key_value.bias",
"mlp.dense_h_to_4h.weight",
"mlp.dense_h_to_4h.bias",
"transformer.word_embeddings.weight",
"lm_head.weight",
]
):
output_size = state.shape[0]
assert output_size % tp_world_size == 0
block_size = output_size // tp_world_size
sharded_weights = torch.split(state, block_size, dim=0)
assert len(sharded_weights) == tp_world_size
for tp_rank, shard in enumerate(sharded_weights):
assert shard.shape[0] == block_size
shards_state_dicts[tp_rank][state_name] = shard.detach().clone()
elif any(
match_suffix(state_name, candidate)
for candidate in [
"self_attention.dense.weight",
"mlp.dense_4h_to_h.weight",
"lm_head.weight",
]
):
input_size = state.shape[1]
assert input_size % tp_world_size == 0
block_size = input_size // tp_world_size
sharded_weights = torch.split(state, block_size, dim=1)
assert len(sharded_weights) == tp_world_size
for tp_rank, shard in enumerate(sharded_weights):
assert shard.shape[1] == block_size
shards_state_dicts[tp_rank][state_name] = shard.detach().clone()
elif any(
match_suffix(state_name, candidate)
for candidate in [
"self_attention.dense.bias",
"mlp.dense_4h_to_h.bias",
]
):
shards_state_dicts[0][state_name] = state.detach().clone()
for tp_rank in range(1, tp_world_size):
shards_state_dicts[tp_rank][state_name] = torch.zeros_like(state)
else:
# We duplicate parameters across tp ranks
for tp_rank in range(tp_world_size):
shards_state_dicts[tp_rank][state_name] = state.detach().clone()
del state_dict[state_name] # delete key from state_dict
del state # delete tensor
# we save state_dict
for tp_rank, (save_path, shard_state_dict) in enumerate(
zip(save_paths, shards_state_dicts)
):
save_path.parent.mkdir(parents=True, exist_ok=True)
torch.save(shard_state_dict, save_path)
save_paths.append(save_path)
return save_paths
if __name__ == "__main__":
model_name = "bigscience/bloom"
save_path = Path("/data/shards")
tp_world_size = 8
dtype = torch.bfloat16
shard_model(model_name, save_path, tp_world_size=tp_world_size, dtype=dtype)