Files
FastDeploy/fastdeploy/model_executor/layers/attention/dsa_attention_backend.py
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周周周 820eb60ec6 [Others] clean code (#6839)
Co-authored-by: “liuruian” <liuruian@baidu.com>
2026-03-14 11:09:28 +08:00

424 lines
16 KiB
Python

"""
# Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
from __future__ import annotations
import math
import os
from dataclasses import dataclass, field
from typing import TYPE_CHECKING, List, Optional, Tuple
import paddle
from fastdeploy.platforms import current_platform
if current_platform.is_cuda():
paddle.enable_compat(scope={"flash_mla"})
from fastdeploy.model_executor.layers.attention.ops import (
get_block_shape_and_split_kv_block,
init_kv_signal_per_query,
init_signal_layerwise,
open_shm_and_get_meta_signal,
)
if TYPE_CHECKING:
from fastdeploy.model_executor.forward_meta import ForwardMeta
from fastdeploy.config import FDConfig
from fastdeploy.model_executor.layers.attention.attention import Attention
from fastdeploy.model_executor.layers.attention.base_attention_backend import (
AttentionBackend,
AttentionMetadata,
)
from fastdeploy.model_executor.layers.attention.utils import init_rank_and_device_id
def yarn_get_mscale(scale=1, mscale=1):
""" """
if scale <= 1:
return 1.0
return 0.1 * mscale * math.log(scale) + 1.0
def compute_slot_mapping(
block_tables: paddle.Tensor, # [num_reqs, max_blocks_per_req]
positions: paddle.Tensor, # [num_tokens] 每个token的位置
batch_id_per_token: paddle.Tensor, # [num_tokens] 每个token属于哪个请求
block_size: int,
) -> paddle.Tensor:
"""
计算 slot_mapping
公式: slot = block_id * block_size + offset_in_block
"""
# 1. 计算每个 token 对应的 block 索引
block_idx = positions // block_size # [num_tokens]
# 2. 从 block_tables 中查表获取 block_id
# block_tables[batch_id_per_token, block_idx]
block_ids = block_tables[batch_id_per_token, block_idx] # [num_tokens]
# 3. 计算在 block 内的偏移
block_offset = positions % block_size # [num_tokens]
# 4. 计算 slot_mapping
slot_mapping = block_ids * block_size + block_offset
return slot_mapping.cast(paddle.int64)
@dataclass
class DSAAttentionMetadata(AttentionMetadata):
"""
DSAAttentionMetadata for Multi-Layer Attention
"""
_dtype: paddle.dtype = paddle.bfloat16
encoder_max_partition_size: int = 32768
max_partition_size: int = 32768
block_tables: Optional[paddle.Tensor] = None
rotary_embs: Optional[paddle.Tensor] = None
attn_mask: Optional[paddle.Tensor] = None
_fuse_kernel_compute_dtype: str = "bf16"
# pd_disaggregation
kv_signal_metadata: Optional[paddle.Tensor] = None
kv_signal_data_list: List[Optional[paddle.Tensor]] = field(default_factory=list)
max_enc_len_this_time: Optional[paddle.Tensor] = None
max_dec_len_this_time: Optional[paddle.Tensor] = None
max_kv_len_this_time: Optional[paddle.Tensor] = None
slot_mapping: Optional[paddle.Tensor] = None
class DSAAttentionBackend(AttentionBackend):
"""
DSA Attention Backend implementation.
"""
__infer_dynamic_dims_fields__ = ["attention_metadata"]
attention_metadata: DSAAttentionMetadata
flash_attn_func: callable = None
def __init__(
self,
fd_config: FDConfig,
kv_num_heads: int,
num_heads: int,
head_dim: int,
encoder_block_shape_q: int = -1,
decoder_block_shape_q: int = -1,
) -> None:
"""
DSAAttentionBackend __init__
"""
super().__init__()
self.attention_metadata: DSAAttentionMetadata = None
# 基础配置
self.block_size: int = fd_config.cache_config.block_size
self.max_seq_len: int = fd_config.model_config.max_model_len
self.rope_theta: float = (
10000.0 if fd_config.model_config.rope_theta is None else fd_config.model_config.rope_theta
)
self.rope_3d: bool = getattr(fd_config.model_config, "rope_3d", False)
self.causal: bool = getattr(fd_config.model_config, "causal", True)
self.speculative_method: str = fd_config.speculative_config.method
self.use_speculate: bool = self.speculative_method is not None
self.speculate_max_draft_token_num: int = fd_config.speculative_config.num_speculative_tokens
self.keep_pd_step_flag: bool = fd_config.speculative_config.model_type == "mtp"
self.num_layers_draft_model: int = int(fd_config.speculative_config.method in ["mtp"])
self.num_heads: int = num_heads
self.head_dim: int = fd_config.model_config.head_dim
self.num_layers: int = fd_config.model_config.num_hidden_layers
# Indexer
self.index_head_dim = fd_config.model_config.index_head_dim
self.index_n_heads = fd_config.model_config.index_n_heads
self.index_topk = fd_config.model_config.index_topk
self.quant_block_size = 128
# For Multi Head Latent Attention
self.kv_lora_rank: int = fd_config.model_config.kv_lora_rank
self.qk_rope_head_dim: int = fd_config.model_config.qk_rope_head_dim
self.qk_head_dim: int = fd_config.model_config.qk_nope_head_dim + fd_config.model_config.qk_rope_head_dim
self.attn_softmax_scale: float = self.qk_head_dim**-0.5
self.rope_scaling = getattr(fd_config.model_config, "rope_scaling", None)
if self.rope_scaling:
mscale_all_dim = fd_config.model_config.rope_scaling.get("mscale_all_dim", False) # 1.0
scaling_factor = fd_config.model_config.rope_scaling["factor"] # 40
mscale = yarn_get_mscale(scaling_factor, float(mscale_all_dim))
self.attn_softmax_scale = self.attn_softmax_scale * mscale * mscale
self.pd_disaggregation_mode: str = fd_config.parallel_config.pd_disaggregation_mode
self.start_layer_index: int = fd_config.model_config.start_layer_index
self.device_id: int = os.getenv("CUDA_VISIBLE_DEVICES", None)
self.rank, self.device_id = init_rank_and_device_id(fd_config)
self.useless_tensor = paddle.randn([1]).cast("int32")
def _cast_scale_inv_to_ue8m0(self, scales_inv: paddle.Tensor, out_dtype=paddle.float32) -> paddle.Tensor:
return paddle.pow(2, paddle.clamp_min(scales_inv, 1e-4).log2().ceil()).to(out_dtype)
def quantize_k_cache(
self,
input_k_cache: paddle.Tensor, # (num_blocks, block_size, h_k, d)
) -> paddle.Tensor:
"""
Quantize the k-cache
For more detail about the layout of K/V, please refer to comments in flash_mla_interface.py
"""
d, d_nope, d_rope, tile_size, num_tiles = 576, 512, 64, 128, 4
assert input_k_cache.shape[-1] == d
num_blocks, block_size, h_k, _ = input_k_cache.shape
assert h_k == 1
input_k_cache = input_k_cache.squeeze(2) # [num_blocks, block_size, d]
input_elem_size = input_k_cache.element_size()
bytes_per_token = d_nope + num_tiles * 4 + input_elem_size * d_rope
result = paddle.empty((num_blocks, block_size + 1, bytes_per_token), dtype=paddle.float8_e4m3fn)[
:, :block_size, :
]
result_k_nope_part = result[..., :d_nope]
result_k_scale_factor = result[..., d_nope : d_nope + num_tiles * 4].view(paddle.float32)
result_k_rope_part = result[..., d_nope + num_tiles * 4 :].view(input_k_cache.dtype)
result_k_rope_part[:] = input_k_cache[..., d_nope:]
for tile_idx in range(0, num_tiles):
cur_scale_factors_inv = (
paddle.abs(input_k_cache[..., tile_idx * tile_size : (tile_idx + 1) * tile_size])
.max(dim=-1)
.values.float()
/ 448.0
) # [num_blocks, block_size]
cur_scale_factors_inv = self._cast_scale_inv_to_ue8m0(cur_scale_factors_inv)
result_k_scale_factor[:, :, tile_idx] = cur_scale_factors_inv
cur_scale_factors_inv.unsqueeze_(-1) # [num_blocks, block_size, 1]
cur_quantized_nope = (
input_k_cache[..., tile_idx * tile_size : (tile_idx + 1) * tile_size].float()
/ cur_scale_factors_inv.float()
).to(paddle.float8_e4m3fn)
result_k_nope_part[..., tile_idx * tile_size : (tile_idx + 1) * tile_size] = cur_quantized_nope
result = result.view(num_blocks, block_size, 1, -1)
return result
def init_attention_metadata(self, forward_meta: ForwardMeta):
"""Initialize attention metadata hence all layers in the forward pass can reuse it."""
metadata = DSAAttentionMetadata()
metadata.max_partition_size = 32768
metadata.encoder_max_partition_size = self.max_seq_len
metadata._dtype = paddle.get_default_dtype()
if metadata._dtype == "bfloat16":
metadata._fuse_kernel_compute_dtype = "bf16"
elif metadata._dtype == "float16":
metadata._fuse_kernel_compute_dtype = "fp16"
elif metadata._dtype == "float32":
metadata._fuse_kernel_compute_dtype = "fp32"
metadata.block_tables = forward_meta.block_tables
metadata.rotary_embs = forward_meta.rotary_embs
metadata.attn_mask = forward_meta.attn_mask
metadata.pre_caches_length = forward_meta.pre_caches_length
get_block_shape_and_split_kv_block(
forward_meta.seq_lens_encoder,
forward_meta.seq_lens_decoder,
forward_meta.seq_lens_this_time,
forward_meta.decoder_batch_ids,
forward_meta.decoder_tile_ids_per_batch,
self.useless_tensor, # not used in mla
forward_meta.decoder_num_blocks_device,
forward_meta.decoder_chunk_size_device,
forward_meta.max_len_tensor_cpu,
self.useless_tensor, # not used in mla
self.useless_tensor, # not used in mla
self.useless_tensor, # not used in mla
forward_meta.kv_batch_ids,
forward_meta.kv_tile_ids_per_batch,
forward_meta.kv_num_blocks_x_cpu,
-1, # not need.
-1, # not need.
-1, # not need.
self.block_size,
)
# MLA
metadata.max_enc_len_this_time = forward_meta.max_len_tensor_cpu[1]
metadata.max_dec_len_this_time = forward_meta.max_len_tensor_cpu[2]
metadata.max_kv_len_this_time = forward_meta.max_len_tensor_cpu[5]
# pd_disaggregation
metadata.kv_signal_data_list = [None] * self.num_layers
if self.pd_disaggregation_mode == "per_chunk":
if not self.keep_pd_step_flag and not forward_meta.is_dummy_or_profile_run:
init_kv_signal_per_query(
forward_meta.seq_lens_encoder,
forward_meta.seq_lens_this_time,
forward_meta.seq_lens_decoder,
self.rank,
self.num_layers + self.num_layers_draft_model,
)
elif self.pd_disaggregation_mode == "per_query":
metadata.kv_signal_metadata = open_shm_and_get_meta_signal(
self.rank, int(self.device_id), self.keep_pd_step_flag
)
self.attention_metadata: AttentionMetadata = metadata
def get_attention_meta(self) -> AttentionMetadata:
"""get_attention_meta"""
return self.attention_metadata
def get_kv_cache_shape(
self,
max_num_blocks: int,
kv_cache_quant_type: str = None,
) -> Tuple[int, int, int, int]:
"""
Calculate kv cache shape for DSA
see FlashMLA readme.md for details
In the "FP8 with scale" format, each token's KV cache is 656 Bytes, structured as:
- **First 512 bytes:** The "quantized NoPE" part, containing 512 `float8_e4m3` values.
- **Next 16 bytes:** Scale factors, containing 4 `float32` values. The first `float32` is the scale for the first 128 `float8_e4m3` values, the second for the next 128, and so on.
- **Last 128 bytes:** The "RoPE" part, containing 64 `bfloat16` values. This part is not quantized for accuracy.
"""
fp8_key_cahe_dim = self.kv_lora_rank + 4 * (self.kv_lora_rank // 128) + 2 * self.qk_rope_head_dim
fp8_indexer_dim = self.index_head_dim + self.index_head_dim // self.quant_block_size * 4
key_cache_shape = [max_num_blocks, 1, self.block_size, fp8_key_cahe_dim]
value_cache_shape = []
indexer_cache_shape = [max_num_blocks, self.block_size, fp8_indexer_dim]
return key_cache_shape, value_cache_shape, indexer_cache_shape
def forward_mixed(
self,
q: paddle.Tensor,
k: paddle.Tensor,
v: paddle.Tensor,
qkv: paddle.Tensor,
compressed_kv: paddle.Tensor,
k_pe: paddle.Tensor,
layer: Attention,
forward_meta: ForwardMeta,
) -> paddle.Tensor:
"""
Mixed模式的前向传播
"""
metadata = self.attention_metadata
# speculate_decoder = self.speculative_method is not None
# speculate_max_tokens = self.speculate_max_draft_token_num
if self.pd_disaggregation_mode == "per_query":
metadata.kv_signal_data_list[layer.layer_id] = init_signal_layerwise(
metadata.kv_signal_metadata,
layer.layer_id + self.start_layer_index,
)
latent_cache = forward_meta.caches[2 * layer.layer_id] if hasattr(forward_meta, "caches") else None
if current_platform.is_cuda():
import flash_mla
from fastdeploy.model_executor.ops.gpu import dsk_attn_write_cache
k_range = paddle.tensor(200.0)
scale = paddle.abs(compressed_kv).max() / k_range
slot_mapping = compute_slot_mapping(
forward_meta.block_tables,
forward_meta.position_ids,
forward_meta.batch_id_per_token,
self.block_size,
)
dsk_attn_write_cache(
compressed_kv,
k_pe,
latent_cache,
slot_mapping,
scale.cast(paddle.float32),
"fp8_ds_mla",
)
fmha_out_prefill = None
if forward_meta.max_len_tensor_cpu[1]: # max_enc_len_this_time
fmha_out_prefill, _, __ = flash_mla.flash_mla_sparse_fwd(
q, # q_input.contiguous(),
k, # kv.unsqueeze(1),
v, # indexer_top_k.unsqueeze(1),
sm_scale=self.attn_softmax_scale,
)
# Decode
# if k is None:
if forward_meta.max_len_tensor_cpu[2]: # max_enc_len_this_time
tile_scheduler_metadata, _ = flash_mla.get_mla_metadata()
fmha_out_decode, _ = flash_mla.flash_mla_with_kvcache(
q.unsqueeze(1).contiguous(),
latent_cache.transpose([0, 2, 1, 3]).contiguous(),
None, # forward_meta.block_tables,
None, # cache_seqlens
512, # self.qk_nope_head_dim,
tile_scheduler_metadata,
None, # num_splits,
self.attn_softmax_scale,
False, # casual
True, # is_fp8_kvcache
v, # indices,
None, # t.attn_sink,
None, # extra_k_cache,
None, # extra_indices_in_kvcache: Optional[torch.Tensor] = None,
None, # topk_length: Optional[torch.Tensor] = None,
None, # extra_topk_length: Optional[torch.Tensor] = None
)
if fmha_out_prefill is not None:
from fastdeploy.model_executor.ops.gpu import (
merge_prefill_decode_output,
)
merge_prefill_decode_output(
fmha_out_prefill,
fmha_out_decode,
forward_meta.seq_lens_encoder,
forward_meta.seq_lens_decoder,
forward_meta.seq_lens_this_time,
forward_meta.cu_seqlens_q,
self.num_heads * 4,
128,
1,
)
return fmha_out_prefill
else:
return fmha_out_decode
return fmha_out_prefill