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2026-07-13 13:18:33 +08:00

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Python

# Copyright (c) Microsoft Corporation.
# SPDX-License-Identifier: Apache-2.0
# DeepSpeed Team
from typing import Iterable, Optional, Tuple
import torch
import deepspeed.comm as dist
from ...allocator import empty_from
from ...inference_utils import ActivationType, DtypeEnum
from .. import *
from ...modules.configs import *
from ...modules.interfaces import *
from ...modules import heuristics
from ...ragged import RaggedBatchWrapper
from .container import QwenNonTransformerContainer, QwenTransformerContainer
class QwenInferenceModel(DSTransformerModelBase):
"""
Inference model implementation for ragged batching for Llama-2 models.
"""
_non_transformer: Optional[QwenNonTransformerContainer]
"""
Embed + unembed container. Specializing the type annotation.
"""
_transformer: Optional[Iterable[QwenTransformerContainer]]
"""
Per-layer transformer container. Specializing the type annotation.
"""
"""
Properties ineherited from `DSInferenceModelBase`
"""
@property
def max_sequence_length(self) -> int:
return self._config.max_seq_length
"""
Properties ineherited from `DSTransformerModelBase`
"""
@property
def num_layers(self) -> int:
return self._config.num_hidden_layers
@property
def model_dim(self) -> int:
return self._config.hidden_size
@property
def vocab_size(self) -> int:
return self._config.vocab_size
@property
def head_size(self) -> int:
return self.model_dim // self.n_heads
@property
def n_heads(self) -> int:
return self._config.num_attention_heads
@property
def intermediate_dim(self) -> int:
return self._config.intermediate_size // 2
@property
def n_heads_kv(self) -> int:
return self._config.hidden_size // self._config.kv_channels
@property
def activation_dtype(self) -> DtypeEnum:
autoset_precision = self._config.bf16 + self._config.fp16 == 0
if autoset_precision:
return DtypeEnum.fp16
if self._config.fp16:
return DtypeEnum.fp16
elif self._config.bf16:
# TODO(ZonePG): bf16 inference results may be different from huggingface bf16,
# because in rms_norm, Qwen still use float() instead of bf16
return DtypeEnum.bf16
else:
raise NotImplementedError("Only fp16 and bf16 are supported")
@property
def mlp_activation_fn(self) -> ActivationType:
return ActivationType.SiGLU
@property
def norm_type(self) -> NormTypeEnum:
return NormTypeEnum.RMSNorm
@property
def positional_embedding_type(self) -> PositionalEmbeddingType:
return PositionalEmbeddingType.rotate_half
@property
def positional_embedding_config(self) -> Optional[RotateHalfConfig]:
return RotateHalfConfig(theta_base=self._config.rotary_emb_base)
def make_norm_layer(self) -> None:
"""
Instantiates the normalization layer for the model. This sets the `self.norm` attribute.
TODO(cmikeh2): In the future we'll distinguish between the different norm objects,
but for now we'll just use the same one for all of them.
"""
norm_config = DSNormConfig(
max_tokens=self._engine_config.state_manager.max_ragged_batch_size,
type=self.norm_type,
channels=self.model_dim,
residual_dtype=self.activation_dtype,
input_dtype=self.activation_dtype,
output_dtype=self.activation_dtype,
eps=self._config.layer_norm_epsilon,
)
self.norm = heuristics.instantiate_pre_norm(norm_config, self._engine_config)
"""
Forward implementations
"""
def _forward_embed(self, ragged_batch: RaggedBatchWrapper) -> torch.Tensor:
"""
Performs the embedding lookup prior to running the transformer of the model.
Arguments:
ragged_batch (RaggedBatchWrapper): The batch to embed.
Returns:
torch.Tensor: The embedded batch.
"""
embed = self.embed(ragged_batch, self._non_transformer.word_emb)
if embed.shape[-1] != self.model_dim:
raise ValueError(f"Embedding output shape {embed.shape} does not match model_dim {self.model_dim}")
return embed
def _forward_transformer_layer(self, layer_idx: int, residual: torch.Tensor, hidden_states: torch.Tensor,
ragged_batch_info: RaggedBatchWrapper) -> Tuple[torch.Tensor, torch.Tensor]:
"""
Executes one (slightly offset) layer of the transformer. This implementation does a peak-ahead
optimization to fuse the layer norm of the next layer into the current layer.
Arguments:
layer_idx (int): The index of the layer to execute.
residual (torch.Tensor): The residual tensor from the previous layer.
hidden_states (torch.Tensor): The hidden states from the previous layer. This is the
hidden states after pre normalization.
ragged_batch_info (RaggedBatchWrapper): The batch metadata.
"""
# TODO(cmikeh2): Distribute ragged_batch_info to all modules
cur_params = self._transformer[layer_idx]
kv_cache = self.state_manager.get_cache(layer_idx)
hidden_states = self.qkv(hidden_states, cur_params.qkv_w, b=cur_params.qkv_b)
hidden_states = self.attn(hidden_states, kv_cache, ragged_batch_info)
hidden_states = self.attn_out(hidden_states, cur_params.attn_out_w, b=None)
if self.tp_size > 1:
dist.all_reduce(hidden_states, group=self._base_mp_group)
residual, hidden_states = self.norm(residual, hidden_states, cur_params.mlp_norm_gamma, beta=None)
# Should be configurable in the future
hidden_states = self.mlp_1(hidden_states, cur_params.mlp_1_w, b=None)
hidden_states = self.mlp_2(hidden_states, cur_params.mlp_2_w, b=None)
if self.tp_size > 1:
dist.all_reduce(hidden_states, group=self._base_mp_group)
if layer_idx != self.num_layers - 1:
next_params = self._transformer[layer_idx + 1]
residual, hidden_states = self.norm(residual, hidden_states, next_params.attn_norm_gamma, beta=None)
else:
# On last layer, we just need to perform the residual add. Adding into the residual
# here is safe.
residual.add_(hidden_states)
return residual, hidden_states
def _forward_unembed(self, hidden_states: torch.Tensor, ragged_batch_info: RaggedBatchWrapper) -> torch.Tensor:
"""
Performs unembedding of the hidden states to logits. This will only sample the final
token of each sequence.
"""
logits = self.unembed(hidden_states,
self._non_transformer.word_unembed,
ragged_batch_info,
gamma=self._non_transformer.final_norm)
if self.tp_size > 1:
comm_buffer = empty_from(self._comm_logits, (self.tp_size, logits.shape[0], logits.shape[1]))
full_logits = empty_from(self._return_logits, (logits.shape[0], self.vocab_size))
dist.all_gather_into_tensor(comm_buffer, logits, group=self._base_mp_group)
full_logits.copy_(comm_buffer.permute(1, 0, 2).reshape(logits.shape[0], self.vocab_size))
return full_logits
else:
return logits
def forward(self, wrapped_batch: RaggedBatchWrapper) -> torch.Tensor:
residual = self._forward_embed(wrapped_batch)
residual, hidden_states = self.norm(residual, None, self._transformer[0].attn_norm_gamma, beta=None)
for layer_idx in range(self.num_layers):
residual, hidden_states = self._forward_transformer_layer(layer_idx, residual, hidden_states,
wrapped_batch)
return self._forward_unembed(residual, wrapped_batch)