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[Diffusion] Apply jit qk_norm to flux1 #17296

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Merged
BBuf merged 1 commit into from
Jan 18, 2026
Merged

[Diffusion] Apply jit qk_norm to flux1 #17296

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42 changes: 37 additions & 5 deletions python/sglang/multimodal_gen/runtime/models/dits/flux.py
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Original file line number Diff line number Diff line change
Expand Up @@ -27,11 +27,12 @@
)
from torch.nn import LayerNorm as LayerNorm

from sglang.jit_kernel.norm import can_use_fused_inplace_qknorm
from sglang.multimodal_gen.configs.models.dits.flux import FluxConfig
from sglang.multimodal_gen.runtime.layers.attention import USPAttention

# from sglang.multimodal_gen.runtime.layers.layernorm import LayerNorm as LayerNorm
from sglang.multimodal_gen.runtime.layers.layernorm import RMSNorm
from sglang.multimodal_gen.runtime.layers.layernorm import RMSNorm, apply_qk_norm
from sglang.multimodal_gen.runtime.layers.linear import ColumnParallelLinear
from sglang.multimodal_gen.runtime.layers.mlp import MLP
from sglang.multimodal_gen.runtime.layers.rotary_embedding import (
Expand Down Expand Up @@ -165,16 +166,47 @@ def forward(
query = query.unflatten(-1, (self.heads, -1))
key = key.unflatten(-1, (self.heads, -1))
value = value.unflatten(-1, (self.heads, -1))
query = self.norm_q(query)
key = self.norm_k(key)
if (
query.is_cuda
and (self.norm_q.variance_epsilon == self.norm_k.variance_epsilon)
and can_use_fused_inplace_qknorm(self.head_dim, query.dtype)
):
query, key = apply_qk_norm(
q=query,
k=key,
q_norm=self.norm_q,
k_norm=self.norm_k,
head_dim=self.head_dim,
allow_inplace=True,
)
else:
query = self.norm_q(query)
key = self.norm_k(key)

if self.added_kv_proj_dim is not None:
encoder_query = encoder_query.unflatten(-1, (self.heads, -1))
encoder_key = encoder_key.unflatten(-1, (self.heads, -1))
encoder_value = encoder_value.unflatten(-1, (self.heads, -1))

encoder_query = self.norm_added_q(encoder_query)
encoder_key = self.norm_added_k(encoder_key)
if (
encoder_query.is_cuda
and (
self.norm_added_q.variance_epsilon
== self.norm_added_k.variance_epsilon
)
and can_use_fused_inplace_qknorm(self.head_dim, encoder_query.dtype)
):
encoder_query, encoder_key = apply_qk_norm(
q=encoder_query,
k=encoder_key,
q_norm=self.norm_added_q,
k_norm=self.norm_added_k,
head_dim=self.head_dim,
allow_inplace=True,
)
else:
encoder_query = self.norm_added_q(encoder_query)
encoder_key = self.norm_added_k(encoder_key)

bsz, seq_len, _, _ = query.shape
query = torch.cat([encoder_query, query], dim=1)
Expand Down
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