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nvfp4-megamoe-kernel/tests/unit/test_d1_raw.py

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Python

"""D1: Test raw unnormalized PV output (epilogue_tma_store without normalize)."""
import torch, math
import cutlass.cute as cute
import cutlass.torch as ct
import cuda.bindings.driver as cuda
from dsv4.kernels.attention.fmha import FmhaKernel
for hd in [64, 128, 256]:
torch.manual_seed(42)
n = 128; m = 128
q = torch.randn(m, hd, 1, dtype=torch.bfloat16, device='cuda')
k = torch.randn(n, hd, 1, dtype=torch.bfloat16, device='cuda')
v = torch.randn(n, hd, dtype=torch.bfloat16, device='cuda')
c = torch.zeros(m, hd, 1, dtype=torch.bfloat16, device='cuda')
# Reference: unnormalized PV = (softmax(QK^T) * scale) @ V (without sum normalization)
qf = q[:,:,0].float(); kf = k[:,:,0].float()
scale = 1.0 / math.sqrt(hd)
attn = qf @ kf.T * scale
attn_unnorm = torch.exp(attn - attn.max(dim=-1, keepdim=True).values) # unnormalized softmax
ref_unnorm = attn_unnorm @ v.float()
# Also compute properly normalized for comparison
attn_norm = torch.softmax(attn, dim=-1)
ref_norm = attn_norm @ v.float()
v_kernel = v.unsqueeze(-1)
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k))
mV = ct.from_dlpack(v_kernel).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v_kernel))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = FmhaKernel(head_dim=hd, s_k=n)
print(f'hd={hd}: Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream)
compiled(mQ, mK, mV, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
# Check against unnormalized reference
cos_unnorm = torch.nn.functional.cosine_similarity(
out.flatten().unsqueeze(0), ref_unnorm.flatten().unsqueeze(0)
).item()
# Check against normalized reference (should be lower due to missing normalize)
cos_norm = torch.nn.functional.cosine_similarity(
out.flatten().unsqueeze(0), ref_norm.flatten().unsqueeze(0)
).item()
print(f'hd={hd}: cos_unnorm={cos_unnorm:.6f} cos_norm={cos_norm:.6f}')