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【Inference Optimize】optimize DeepSeek_v3 #3349

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【Inference Optimize】optimize DeepSeek_v3 #3349

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fde43aa
optimize DeepSeek_v3 Eliminate redundant calculations & encoder using…
chang-wenbin Aug 12, 2025
ba92551
Merge branch 'develop' into DSK_OPT1
XieYunshen Aug 12, 2025
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43 changes: 31 additions & 12 deletions fastdeploy/model_executor/layers/attention/mla_attention_backend.py
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,11 @@
import paddle
from paddle.nn.functional.flash_attention import flash_attn_unpadded

try:
from paddle.nn.functional.flash_attention import flash_attention_v3_varlen
except:
flash_attention_v3_varlen = None

from fastdeploy.model_executor.layers.attention.ops import (
get_block_shape_and_split_kv_block,
init_kv_signal_per_query,
Expand Down Expand Up @@ -91,6 +96,7 @@ class MLAAttentionBackend(AttentionBackend):
"""

__infer_dynamic_dims_fields__ = ["attention_metadata"]
flash_attn_func: callable = None
attention_metadata: MLAAttentionMetadata

def __init__(
Expand Down Expand Up @@ -147,6 +153,21 @@ def __init__(
self.device_id: int = os.getenv("CUDA_VISIBLE_DEVICES", None)

self.rank, self.device_id = init_rank_and_device_id(fd_config)
if self.flash_attn_func is None:
prop = paddle.device.cuda.get_device_properties()
cc = prop.major * 10 + prop.minor
is_current_sm_supported = cc >= 90
is_paddle_supported = any(num >= 90 for num in paddle.version.cuda_archs())
if is_current_sm_supported and is_paddle_supported:
self.flash_attn_func = flash_attention_v3_varlen
print("The current platform supports Flash Attention V3.")
self.flash_attn_kwargs = {}
else:
self.flash_attn_func = flash_attn_unpadded
self.flash_attn_kwargs = {"scale": self.head_dim**-0.5, "training": False}
print(
"The current platform does not support Flash Attention V3, so Flash Attention V2 will be used instead."
)

def init_attention_metadata(self, forward_meta: ForwardMeta):
"""Initialize attention metadata hence all layers in the forward pass can reuse it."""
Expand Down Expand Up @@ -269,17 +290,16 @@ def forward_extend(
)

# Flash注意力计算
fmha_out = flash_attn_unpadded(
fmha_out = self.flash_attn_func(
q,
k,
v,
forward_meta.cu_seqlens_q,
forward_meta.cu_seqlens_k,
metadata.max_enc_len_this_time,
metadata.max_enc_len_this_time,
self.attn_softmax_scale,
causal=True,
training=False,
max_seqlen_q=forward_meta.max_len_tensor_cpu[0],
max_seqlen_k=forward_meta.max_len_tensor_cpu[3],
causal=self.causal,
**self.flash_attn_kwargs,
)[0]

return fmha_out
Expand Down Expand Up @@ -418,17 +438,16 @@ def forward_mixed(
)

# FA
fmha_out = flash_attn_unpadded(
fmha_out = self.flash_attn_func(
q,
k,
v,
forward_meta.cu_seqlens_q,
forward_meta.cu_seqlens_k,
metadata.max_enc_len_this_time,
metadata.max_enc_len_this_time,
self.attn_softmax_scale,
causal=True,
training=False,
max_seqlen_q=forward_meta.max_len_tensor_cpu[0],
max_seqlen_k=forward_meta.max_len_tensor_cpu[3],
causal=self.causal,
**self.flash_attn_kwargs,
)[0]

return fmha_out
Expand Down
59 changes: 21 additions & 38 deletions fastdeploy/model_executor/models/deepseek_v3.py
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Original file line number Diff line number Diff line change
Expand Up @@ -316,30 +316,23 @@ def forward(
mask_encoder_batch: paddle.Tensor,
):
""" """
layernorm_out = hidden_states
fmha_out = paddle.zeros(
shape=[
layernorm_out.shape[0],
self.num_attention_heads_tp * self.v_head_dim,
],
dtype=layernorm_out.dtype,
)

if forward_meta.max_len_tensor_cpu[1]: # max_enc_len_this_time
query = self.q_a_proj(layernorm_out)
query = self.q_a_layernorm(query)
query = self.q_b_proj(query)
fmha_out = None
# NOTE: (changwenbin) Bring out the public calculation in PD MIX to avoid repeated calculation.
query = self.q_a_proj(hidden_states)
query = self.q_a_layernorm(query)
query = self.q_b_proj(query)
query = query.reshape([-1, self.num_attention_heads_tp, self.qk_head_dim])
query_nope, query_pe = query.split([self.qk_nope_head_dim, self.qk_rope_head_dim], axis=-1)

query = query.reshape([-1, self.num_attention_heads_tp, self.qk_head_dim])
query_nope, query_pe = query.split([self.qk_nope_head_dim, self.qk_rope_head_dim], axis=-1)
compressed_kv = self.kv_a_proj_with_mqa(hidden_states)
compressed_kv, key_pe = compressed_kv.split([self.kv_lora_rank, self.qk_rope_head_dim], axis=-1)
key_pe = key_pe.reshape([-1, 1, self.qk_rope_head_dim])
compressed_kv = self.kv_a_layernorm(compressed_kv)

compressed_kv = self.kv_a_proj_with_mqa(layernorm_out)
compressed_kv, key_pe = compressed_kv.split([self.kv_lora_rank, self.qk_rope_head_dim], axis=-1)
key_pe = key_pe.reshape([-1, 1, self.qk_rope_head_dim])
compressed_kv = self.kv_a_layernorm(compressed_kv)

query_pe, key_pe = self.rotary_emb(position_ids, query_pe, key_pe)
query_pe, key_pe = self.rotary_emb(position_ids, query_pe, key_pe)

if forward_meta.max_len_tensor_cpu[1]: # max_enc_len_this_time
# NOTE: (changwenbin) We will take the public part
key_value = self.kv_b_proj(compressed_kv)
key_value = key_value.reshape(
[
Expand Down Expand Up @@ -371,23 +364,10 @@ def forward(
fmha_out_prefill = fmha_out_prefill.reshape([-1, self.num_attention_heads_tp * self.v_head_dim])
fmha_out_prefill = fmha_out_prefill * mask_encoder_batch.cast(fmha_out_prefill.dtype)

fmha_out = fmha_out + fmha_out_prefill
if forward_meta.max_len_tensor_cpu[2]: # max_dec_len_this_time
query = self.q_a_proj(layernorm_out)
query = self.q_a_layernorm(query)
ln_out_or_q_c = query

compressed_kv = self.kv_a_proj_with_mqa(layernorm_out)
compressed_kv, key_pe = compressed_kv.split([self.kv_lora_rank, self.qk_rope_head_dim], axis=-1)
key_pe = key_pe.reshape([-1, 1, self.qk_rope_head_dim])
compressed_kv = self.kv_a_layernorm(compressed_kv)

query = self.q_b_proj(ln_out_or_q_c)
query = query.reshape([-1, self.num_attention_heads_tp, self.qk_head_dim])

query_nope, query_pe = query.split([self.qk_nope_head_dim, self.qk_rope_head_dim], axis=-1)
query_pe, key_pe = self.rotary_emb(position_ids, query_pe, key_pe)
fmha_out = fmha_out_prefill

if forward_meta.max_len_tensor_cpu[2]: # max_dec_len_this_time
# NOTE: (changwenbin) We will take the public part
q_nope_out = self.kv_b_proj_bmm(query_nope.transpose([1, 0, 2]), proj_type="k").transpose([1, 0, 2])

q_input = paddle.concat([q_nope_out, query_pe], axis=-1)
Expand Down Expand Up @@ -416,7 +396,10 @@ def forward(
.transpose([1, 0, 2])
.reshape([-1, self.num_attention_heads_tp * self.v_head_dim])
)
fmha_out = fmha_out + fmha_out_decode
if fmha_out is None:
fmha_out = fmha_out_decode
else:
fmha_out = fmha_out + fmha_out_decode

output = self.o_proj(fmha_out)
return output
Expand Down
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