[v1] Add FlashAttention selection and implement normal / padding-free / dynamic batching (#10469)

This commit is contained in:
jiaqiw09
2026-05-21 17:14:19 +08:00
committed by GitHub
parent 7e20db5735
commit bdcb92d035
23 changed files with 507 additions and 105 deletions

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@@ -20,7 +20,6 @@ import sys
import time
from collections import defaultdict
from concurrent.futures import ThreadPoolExecutor
from dataclasses import dataclass, field
from datetime import timedelta
from typing import TYPE_CHECKING, Any, Optional
@@ -584,7 +583,7 @@ class ModuleProfilerCallback(TrainerCallback):
if matched:
logger.info_rank0(
f"ModuleProfiler: registered hooks on {len(matched)} modules: {matched[:5]}"
+ (f" ... (+{len(matched)-5} more)" if len(matched) > 5 else "")
+ (f" ... (+{len(matched) - 5} more)" if len(matched) > 5 else "")
)
else:
logger.warning_rank0(f"ModuleProfiler: no modules matched patterns {self.patterns}")
@@ -616,7 +615,7 @@ class ModuleProfilerCallback(TrainerCallback):
bwd = self._backward_times.get(name, [])
fwd_mean = sum(fwd) / len(fwd) if fwd else 0.0
bwd_mean = sum(bwd) / len(bwd) if bwd else 0.0
lines.append(f" {name}: fwd={fwd_mean:.3f}, bwd={bwd_mean:.3f}, total={fwd_mean+bwd_mean:.3f}")
lines.append(f" {name}: fwd={fwd_mean:.3f}, bwd={bwd_mean:.3f}, total={fwd_mean + bwd_mean:.3f}")
logger.info_rank0("\n".join(lines))
self._forward_times.clear()

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@@ -12,6 +12,7 @@
# See the License for the specific language governing permissions and
# limitations under the License.
from ..utils.types import AttentionFunction
from .arg_parser import InputArgument, get_args
from .arg_utils import BatchingStrategy, ModelClass, SampleBackend
from .data_args import DataArguments
@@ -21,6 +22,7 @@ from .training_args import TrainingArguments
__all__ = [
"AttentionFunction",
"BatchingStrategy",
"DataArguments",
"InputArgument",

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@@ -15,6 +15,7 @@
from dataclasses import dataclass, field
from ..utils.types import AttentionFunction
from .arg_utils import ModelClass, PluginConfig, get_plugin_config
@@ -32,6 +33,12 @@ class ModelArguments:
default=False,
metadata={"help": "Trust remote code from Hugging Face."},
)
flash_attn: AttentionFunction = field(
default=AttentionFunction.SDPA,
metadata={
"help": "Attention implementation to use: eager, sdpa, or flash_attention_2. SDPA is the default implementation for models."
},
)
model_class: ModelClass = field(
default=ModelClass.LLM,
metadata={"help": "Model class from Hugging Face."},
@@ -54,6 +61,12 @@ class ModelArguments:
)
def __post_init__(self) -> None:
supported_flash_attn = [item.value for item in AttentionFunction]
if self.flash_attn not in supported_flash_attn:
raise ValueError(
f"Unsupported `flash_attn`: {self.flash_attn}. Supported values are: {supported_flash_attn}."
)
self.init_config = get_plugin_config(self.init_config)
self.peft_config = get_plugin_config(self.peft_config)
self.kernel_config = get_plugin_config(self.kernel_config)

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@@ -116,3 +116,9 @@ class TrainingArguments:
self.dist_config = get_plugin_config(self.dist_config)
self.optim_config = get_plugin_config(self.optim_config)
self.lr_scheduler_config = get_plugin_config(self.lr_scheduler_config)
if str(self.batching_strategy) == str(BatchingStrategy.DYNAMIC_BATCHING):
if self.max_steps is None or self.max_steps <= 0:
raise ValueError("`dynamic_batching` requires `max_steps` because it is step-driven.")
if self.save_epochs is not None:
raise ValueError("`save_epochs` is not supported with `dynamic_batching`; use `save_steps` instead.")

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@@ -34,7 +34,7 @@ import torch.nn.functional as F
from ..accelerator.helper import ReduceOp
from ..accelerator.interface import Dim, DistributedInterface
from ..config import TrainingArguments
from ..config import BatchingStrategy, TrainingArguments
from ..utils import logging
from ..utils.callbacks import (
CallbackHandler,
@@ -147,13 +147,19 @@ class BaseTrainer:
from ..plugins.model_plugins.parallelization.sequence_parallel import SequenceParallelModelPlugin
if model.config._attn_implementation != "flash_attention_2":
logger.warning_rank0(
"Sequence parallelism is optimized for flash attention only. Replace the attention implementation to flash_attention_2."
raise ValueError(
"Sequence parallelism requires flash attention. Please set `flash_attn: flash_attention_2`."
)
model.config._attn_implementation = "flash_attention_2"
SequenceParallelModelPlugin(self.args.dist_config.get("cp_mode", "ulysses"))(model, self.args.dist_config)
def _create_batch_generator(self) -> None:
if (
self.args.batching_strategy == BatchingStrategy.PADDING_FREE
and getattr(self.model.config, "_attn_implementation", None) != "flash_attention_2"
):
raise ValueError("`padding_free` requires `flash_attn: flash_attention_2`.")
self.train_batch_generator = BatchGenerator(
dataset=self.train_dataset,
renderer=self.renderer,
@@ -237,6 +243,7 @@ class BaseTrainer:
self.train_batch_generator.set_epoch(epoch)
self.callback_handler.on_epoch_begin(self.args, self.state)
# BatchGenerator is an iterator; each loop step calls its __next__ to produce one optimizer step.
for micro_batches in self.train_batch_generator:
self.global_step += 1

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@@ -120,6 +120,7 @@ class ModelEngine:
init_device = DistributedInterface().current_device
init_kwargs = {} if self._deepspeed_zero3_enabled else {"device_map": init_device}
logger.info_rank0(f"Using attention implementation: {self.args.flash_attn}.")
if self.args.quant_config is not None:
from ..plugins.model_plugins.quantization import QuantizationPlugin
@@ -164,6 +165,7 @@ class ModelEngine:
self.args.model,
config=self.model_config,
dtype="auto",
attn_implementation=self.args.flash_attn,
trust_remote_code=self.args.trust_remote_code,
**init_kwargs,
)

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@@ -42,6 +42,8 @@ from .rendering import Renderer
logger = logging.get_logger(__name__)
__all__ = ["BatchGenerator"]
def default_collate_fn(buffer: StatefulBuffer, batch_info: BatchInfo) -> list[BatchInput] | None:
micro_batch_size = batch_info["micro_batch_size"]
@@ -102,19 +104,18 @@ class BatchGenerator(Iterator):
if not self.drop_last:
raise ValueError("Drop last must be True.")
self._batch_info: BatchInfo = {
"micro_batch_size": self.micro_batch_size,
"num_micro_batch": self.num_micro_batch,
"cutoff_len": self.cutoff_len,
}
self._init_data_provider()
self._is_resuming: bool = False
self._data_iter = iter(self._data_provider)
self._buffer = StatefulBuffer()
self._batch_info: BatchInfo = {
"micro_batch_size": self.micro_batch_size,
"num_micro_batch": self.num_micro_batch,
"cutoff_len": self.cutoff_len,
"data_iter": self._data_iter,
}
logger.info_rank0(
f"Init unified data loader with global batch size {self.global_batch_size}, "
f"micro batch size {self.micro_batch_size}, "
@@ -137,12 +138,19 @@ class BatchGenerator(Iterator):
else:
raise NotImplementedError("Iterable dataset is not supported yet.")
if self.batching_strategy == BatchingStrategy.NORMAL:
batch_size = self.micro_batch_size * self.num_micro_batch
else:
from ...plugins.trainer_plugins.batching import BatchingPlugin
batch_size = BatchingPlugin(self.batching_strategy).get_data_provider_batch_size(self._batch_info)
generator_seed = torch.Generator()
generator_seed.manual_seed(self.seed)
self._data_provider = StatefulDataLoader(
self.dataset,
batch_size=self.micro_batch_size * self.num_micro_batch,
batch_size=batch_size,
sampler=sampler,
num_workers=self.batching_workers,
collate_fn=self.renderer.process_samples,
@@ -156,8 +164,7 @@ class BatchGenerator(Iterator):
else:
from ...plugins.trainer_plugins.batching import BatchingPlugin
self._length = BatchingPlugin(self.batching_strategy).compute_length(self._data_provider)
raise NotImplementedError("Batching strategy other than NORMAL is not supported yet.")
self._length = BatchingPlugin(self.batching_strategy).compute_length(self._data_provider, self._batch_info)
def __len__(self) -> int:
return self._length
@@ -190,7 +197,7 @@ class BatchGenerator(Iterator):
else:
from ...plugins.trainer_plugins.batching import BatchingPlugin
BatchingPlugin(self.batching_strategy).fill_buffer(self._buffer, self._batch_info)
BatchingPlugin(self.batching_strategy).fill_buffer(self._buffer, self._batch_info, self._next_samples)
def _generate_batch(self) -> list[BatchInput] | None:
if self.batching_strategy == BatchingStrategy.NORMAL:
@@ -200,6 +207,20 @@ class BatchGenerator(Iterator):
return BatchingPlugin(self.batching_strategy).generate_batch(self._buffer, self._batch_info)
def _next_samples(self, restart: bool) -> list[ModelInput] | None:
try:
return next(self._data_iter)
except StopIteration:
if not restart:
return None
# Dynamic batching may restart the provider to fill one token-budgeted batch.
self._data_iter = iter(self._data_provider)
try:
return next(self._data_iter)
except StopIteration:
return None
def state_dict(self) -> dict[str, Any]:
return {
"buffer": self._buffer.state_dict(),

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@@ -12,23 +12,197 @@
# See the License for the specific language governing permissions and
# limitations under the License.
from collections.abc import Callable
from math import ceil
from typing import Any
import torch
from torch.utils.data import default_collate
from ...utils.constants import IGNORE_INDEX
from ...utils.helper import pad_and_truncate
from ...utils.objects import StatefulBuffer
from ...utils.plugin import BasePlugin
from ...utils.types import BatchInfo, BatchInput, DataLoader
from ...utils.types import BatchInfo, BatchInput, DataLoader, ModelInput
class BatchingPlugin(BasePlugin):
def compute_length(self, data_provider: DataLoader) -> int:
def get_data_provider_batch_size(self, batch_info: BatchInfo) -> int:
"""Return the raw data provider batch size for this batching strategy."""
return self["get_data_provider_batch_size"](batch_info)
def compute_length(self, data_provider: DataLoader, batch_info: BatchInfo) -> int:
"""Compute the length of the batch generator.
The approximate length is used to calculate the lr schedule.
"""
raise NotImplementedError()
return self["compute_length"](data_provider, batch_info)
def fill_buffer(self, buffer: StatefulBuffer, batch_info: BatchInfo) -> None:
def fill_buffer(
self,
buffer: StatefulBuffer,
batch_info: BatchInfo,
next_samples: Callable[[bool], list[ModelInput] | None],
) -> None:
"""Fill the buffer with data."""
raise NotImplementedError()
return self["fill_buffer"](buffer, batch_info, next_samples)
def generate_batch(self, buffer: StatefulBuffer, batch_info: BatchInfo) -> list[BatchInput] | None:
"""Generate a batch from the buffer."""
raise NotImplementedError()
return self["generate_batch"](buffer, batch_info)
def _get_dynamic_micro_batch_sizes(samples: list[ModelInput], batch_info: BatchInfo) -> list[int]:
"""Return sample counts for micro batches formed by one padded-token budget."""
budget = batch_info["cutoff_len"] * batch_info["micro_batch_size"]
cutoff_len = batch_info["cutoff_len"]
sizes = []
index = 0
while index < len(samples) and len(sizes) < batch_info["num_micro_batch"]:
max_sample_len = 0
used = 0
is_complete = False
while index + used < len(samples):
sample_len = min(len(samples[index + used]["input_ids"]), cutoff_len)
padded_tokens = max(max_sample_len, sample_len) * (used + 1)
if used > 0 and padded_tokens > budget:
is_complete = True
break
max_sample_len = max(max_sample_len, sample_len)
used += 1
if max_sample_len * used >= budget:
is_complete = True
break
if used == 0 or not is_complete:
break
sizes.append(used)
index += used
return sizes
def _pack_padding_free_samples(samples: list[ModelInput], cutoff_len: int) -> BatchInput | None:
"""Pack fixed samples into one padding-free sequence without a token budget."""
packed: dict[str, list[Any]] = {}
position_ids: list[int] = []
for sample_index, sample in enumerate(samples):
# Padding-free still truncates each sample by cutoff_len before packing
# all samples into one contiguous sequence.
sample_len = min(len(sample["input_ids"]), cutoff_len)
if sample_len <= 0:
continue
for key, value in sample.items():
if key in ("attention_mask", "position_ids") or isinstance(value, str):
continue
if key not in packed:
packed[key] = []
sliced_value = list(value[:sample_len])
if sample_index > 0 and sliced_value:
if key == "labels":
sliced_value[0] = IGNORE_INDEX
elif key == "loss_weights":
sliced_value[0] = 0.0
packed[key].extend(sliced_value)
position_ids.extend(range(sample_len))
if not position_ids:
return None
packed["position_ids"] = position_ids
packed["attention_mask"] = [1] * len(position_ids)
return {key: torch.tensor(value).unsqueeze(0) for key, value in packed.items()}
@BatchingPlugin("padding_free").register("get_data_provider_batch_size")
def get_padding_free_data_provider_batch_size(batch_info: BatchInfo) -> int:
return batch_info["micro_batch_size"] * batch_info["num_micro_batch"]
@BatchingPlugin("padding_free").register("compute_length")
def compute_padding_free_length(data_provider: DataLoader, batch_info: BatchInfo) -> int:
return len(data_provider)
@BatchingPlugin("padding_free").register("fill_buffer")
def fill_padding_free_buffer(
buffer: StatefulBuffer,
batch_info: BatchInfo,
next_samples: Callable[[bool], list[ModelInput] | None],
) -> None:
while len(buffer) < batch_info["micro_batch_size"] * batch_info["num_micro_batch"]:
samples = next_samples(False)
if samples is None:
break
buffer.put(samples)
@BatchingPlugin("padding_free").register("generate_batch")
def generate_padding_free_batch(buffer: StatefulBuffer, batch_info: BatchInfo) -> list[BatchInput] | None:
micro_batch_size = batch_info["micro_batch_size"]
num_micro_batch = batch_info["num_micro_batch"]
cutoff_len = batch_info["cutoff_len"]
batch_size = micro_batch_size * num_micro_batch
if len(buffer) < batch_size:
return None
samples = buffer.get(batch_size)
batch = []
for i in range(num_micro_batch):
micro_batch = samples[i * micro_batch_size : (i + 1) * micro_batch_size]
packed_micro_batch = _pack_padding_free_samples(micro_batch, cutoff_len)
if packed_micro_batch is None:
return None
batch.append(packed_micro_batch)
return batch
@BatchingPlugin("dynamic_batching").register("get_data_provider_batch_size")
def get_dynamic_batching_data_provider_batch_size(batch_info: BatchInfo) -> int:
return 1
@BatchingPlugin("dynamic_batching").register("compute_length")
def compute_dynamic_batching_length(data_provider: DataLoader, batch_info: BatchInfo) -> int:
batch_size = batch_info["micro_batch_size"] * batch_info["num_micro_batch"]
return ceil(len(data_provider) / batch_size)
@BatchingPlugin("dynamic_batching").register("fill_buffer")
def fill_dynamic_batching_buffer(
buffer: StatefulBuffer,
batch_info: BatchInfo,
next_samples: Callable[[bool], list[ModelInput] | None],
) -> None:
while len(_get_dynamic_micro_batch_sizes(buffer.samples, batch_info)) < batch_info["num_micro_batch"]:
samples = next_samples(True)
if samples is None:
break
buffer.put(samples)
@BatchingPlugin("dynamic_batching").register("generate_batch")
def generate_dynamic_batching_batch(buffer: StatefulBuffer, batch_info: BatchInfo) -> list[BatchInput] | None:
micro_batch_sample_counts = _get_dynamic_micro_batch_sizes(buffer.samples, batch_info)
if len(micro_batch_sample_counts) < batch_info["num_micro_batch"]:
return None
batch = []
cutoff_len = batch_info["cutoff_len"]
for num_samples in micro_batch_sample_counts:
samples = buffer.get(num_samples)
batch.append(default_collate(pad_and_truncate(samples, cutoff_len)))
return batch

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@@ -61,6 +61,9 @@ def load_checkpoint_fsdp2(model: HFModel, optimizer: torch.optim.Optimizer, ckpt
@DistributedPlugin("deepspeed").register()
def shard_model_deepspeed(model: HFModel, dist_config: PluginConfig, **kwargs) -> HFModel:
if dist_config.get("cp_size", 1) > 1:
raise ValueError("CP currently requires `dist_config.name: fsdp2`.")
from .deepspeed import DeepSpeedEngine
return DeepSpeedEngine(

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@@ -33,6 +33,10 @@ class StatefulBuffer:
def size(self) -> int:
return self._buffer_size
@property
def samples(self) -> list[ModelInput]:
return self._buffer
def put(self, samples: list[ModelInput]) -> None:
"""Add samples to the buffer."""
num_tokens = sum(len(sample["input_ids"]) for sample in samples)

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@@ -12,7 +12,7 @@
# See the License for the specific language governing permissions and
# limitations under the License.
from collections.abc import Iterator
from enum import StrEnum, unique
from typing import TYPE_CHECKING, Any, Literal, NamedTuple, NotRequired, TypedDict, Union
@@ -54,6 +54,13 @@ else:
ProcessGroup = None
@unique
class AttentionFunction(StrEnum):
EAGER = "eager"
SDPA = "sdpa"
FLASH_ATTENTION_2 = "flash_attention_2"
class DatasetInfo(TypedDict, total=False):
path: str
"""Local file path."""
@@ -171,8 +178,6 @@ class BatchInfo(TypedDict):
"""Number of micro batches."""
cutoff_len: int
"""Cutoff length."""
data_iter: Iterator[list[ModelInput]]
"""Data iterator."""
class ModelOutput(NamedTuple):