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nvfp4-megamoe-kernel/tests/unit/test_d2_scale.py

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Python

"""
D2: Scale test — more heads, larger hd.
"""
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
def test_multihead(hd=64, n_h=1, batch=1, T=128, s_k=128):
torch.manual_seed(42)
q = torch.randn(batch, n_h, T, hd, dtype=torch.bfloat16, device='cuda')
k = torch.randn(batch, s_k, hd, dtype=torch.bfloat16, device='cuda')
v = torch.randn(batch, s_k, hd, dtype=torch.bfloat16, device='cuda')
# FP32 reference (un-normalized)
qf = q.float()
kf = k.float()
vf = v.float()
scale = 1.0 / math.sqrt(hd)
ref_unnorm = torch.zeros(batch, n_h, T, hd, dtype=torch.float32, device='cuda')
for b in range(batch):
for h in range(n_h):
attn = qf[b, h] @ kf[b].T * scale
attn_max = attn.max(dim=-1, keepdim=True)[0]
attn_exp = torch.exp(attn - attn_max)
ref_unnorm[b, h] = attn_exp @ vf[b]
kernel = FmhaKernel(head_dim=hd, s_k=s_k, use_smem_p=False, normalize=False)
pv_n_tile = kernel.pv_n_tile
n_pv_tiles = hd // pv_n_tile
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
# Compile once
q0 = q[0, 0].unsqueeze(-1)
k0 = k[0].unsqueeze(-1)
v0_tile = v[0, :, 0:pv_n_tile].contiguous()
v0_k = v0_tile.unsqueeze(-1)
c0 = torch.zeros(T, pv_n_tile, 1, dtype=torch.bfloat16, device='cuda')
lse0 = torch.zeros(T, 1, 1, dtype=torch.float32, device='cuda')
mQ = ct.from_dlpack(q0).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q0))
mK = ct.from_dlpack(k0).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k0))
mV = ct.from_dlpack(v0_k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v0_k))
mC = ct.from_dlpack(c0).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c0))
mLSE = ct.from_dlpack(lse0).mark_layout_dynamic(leading_dim=ct.get_leading_dim(lse0))
print(f' Compiling (hd={hd}, n_h={n_h})...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream, mLSE)
o = torch.zeros(batch, n_h, T, hd, dtype=torch.bfloat16, device='cuda')
for b in range(batch):
for h in range(n_h):
q_h = q[b, h].unsqueeze(-1)
k_b = k[b].unsqueeze(-1)
v_b = v[b]
c_h = torch.zeros(T, hd, dtype=torch.bfloat16, device='cuda')
for nt in range(n_pv_tiles):
v_start = nt * pv_n_tile
v_end = v_start + pv_n_tile
v_tile = v_b[:, v_start:v_end].contiguous()
v_k = v_tile.unsqueeze(-1)
c_tile = torch.zeros(T, pv_n_tile, 1, dtype=torch.bfloat16, device='cuda')
lse0.zero_()
mQ = ct.from_dlpack(q_h).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q_h))
mK = ct.from_dlpack(k_b).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k_b))
mV = ct.from_dlpack(v_k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v_k))
mC = ct.from_dlpack(c_tile).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c_tile))
mLSE = ct.from_dlpack(lse0).mark_layout_dynamic(leading_dim=ct.get_leading_dim(lse0))
compiled(mQ, mK, mV, mC, stream, mLSE)
c_h[:, v_start:v_end] = c_tile[:, :, 0]
o[b, h] = c_h
torch.cuda.synchronize()
cos = torch.nn.functional.cosine_similarity(
o.flatten().float().unsqueeze(0), ref_unnorm.flatten().unsqueeze(0)
).item()
print(f' hd={hd}, n_h={n_h}, batch={batch}: cos {cos:.6f} {"PASS" if cos >= 0.99 else "FAIL"}')
def test():
print("=== D2: Scale Test ===\n")
# hd=64
test_multihead(64, 16, 1, 128, 128)
test_multihead(64, 64, 1, 128, 128) # Flash decode config (hd=64 test)
# hd=128
test_multihead(128, 2, 1, 128, 128)
test_multihead(128, 8, 1, 128, 128)
# hd=256
test_multihead(256, 2, 1, 128, 128)
if __name__ == '__main__':
test()