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[DSV4.1] Avoid PDL for small target routers on SM103 #39941

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[DSV4.1] Avoid PDL for small target routers on SM103 #39941

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f4a4da0
[DSV4.1] Avoid PDL for small target routers on SM103
BBuf Sep 17, 2026
914b368
Remove test changes from small-router PDL fix
BBuf Sep 18, 2026
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13 changes: 12 additions & 1 deletion python/sglang/kernels/ops/moe/moe_fused_gate.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,12 @@
import triton.language as tl
from triton.language.extra import libdevice

from sglang.kernels.jit.utils import cache_once, is_arch_support_pdl, load_jit
from sglang.kernels.jit.utils import (
cache_once,
get_jit_cuda_arch,
is_arch_support_pdl,
load_jit,
)
from sglang.kernels.kernel_api_logging import debug_kernel_api
from sglang.kernels.ops.moe import moe_route_radix

Expand Down Expand Up @@ -442,6 +447,12 @@ def moe_fused_gate(
num_warps = 1 if BLOCK_N <= 512 else 4
grid = (triton.cdiv(M, BLOCK_M),)
use_pdl = is_arch_support_pdl()
if use_pdl and scoring_func_int == 1 and N == 384 and K == 6 and M <= 8:
# On SM103, early-launching the small DSV4.1 target router increases
# latency when it overlaps with mHC/shared-expert work. Use ordinary
# stream dependencies; keep PDL for the draft router and larger batches.
arch = get_jit_cuda_arch()
use_pdl = (arch.major, arch.minor) != (10, 3)
extra = {"launch_pdl": True} if use_pdl else {}
# Never alias an output as the fallback for an unused pointer arg: when
# Dynamo cannot analyze the kernel (PDL inline asm) it treats every pointer
Expand Down
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