119 lines
4.8 KiB
Python
119 lines
4.8 KiB
Python
"""
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Test SMEM accumulator FMHA kernel: multi-KV-tile with in-kernel O accumulation.
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No Python KV merge needed — the kernel handles acc_scale internally.
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"""
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import torch, math, sys
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import cutlass.cute as cute
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import cutlass.torch as ct
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import cuda.bindings.driver as cuda
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from dsv4.kernels.attention.fmha_smem_acc import FmhaKernel
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def test_smem_acc(hd=64, s_k=256, use_smem_p=False, normalize=False):
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m = 128
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n_kv_tiles = s_k // 128
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torch.manual_seed(42)
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q = torch.randn(m, hd, 1, dtype=torch.bfloat16, device='cuda')
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k = torch.randn(s_k, hd, 1, dtype=torch.bfloat16, device='cuda')
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v = torch.randn(s_k, hd, dtype=torch.bfloat16, device='cuda')
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c = torch.zeros(m, hd, 1, dtype=torch.bfloat16, device='cuda')
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# FP32 reference
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qf = q[:, :, 0].float()
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kf = k[:, :, 0].float()
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scale = 1.0 / math.sqrt(hd)
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attn_max = (qf @ kf.T * scale).max(dim=-1, keepdim=True)[0]
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attn_exp = torch.exp(qf @ kf.T * scale - attn_max)
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attn_sum = attn_exp.sum(dim=-1, keepdim=True)
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ref_norm = (attn_exp / attn_sum) @ v.float()
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ref_unnorm = attn_exp @ v.float()
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lse_tensor = torch.zeros(m, 1, 1, dtype=torch.float32, device='cuda')
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row_sums_tensor = torch.zeros(m, 1, 1, dtype=torch.float32, device='cuda')
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kernel = FmhaKernel(head_dim=hd, s_k=s_k, use_smem_p=use_smem_p, normalize=normalize)
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pv_n_tile = kernel.pv_n_tile
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n_pv_tiles = kernel.n_pv_tiles
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stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
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# Compile
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v_tile = v[:, 0:pv_n_tile].contiguous()
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v_kernel = v_tile.unsqueeze(-1)
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c_tile = torch.zeros(m, pv_n_tile, 1, dtype=torch.bfloat16, device='cuda')
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mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
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mK = ct.from_dlpack(k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k))
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mV = ct.from_dlpack(v_kernel).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v_kernel))
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mC = ct.from_dlpack(c_tile).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c_tile))
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mLSE = ct.from_dlpack(lse_tensor).mark_layout_dynamic(leading_dim=ct.get_leading_dim(lse_tensor))
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mRS = ct.from_dlpack(row_sums_tensor).mark_layout_dynamic(leading_dim=ct.get_leading_dim(row_sums_tensor))
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# Simple GMEM tensor (non-dynamic-layout) for SMEM accumulator TMA store
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c_simple_tensor = c_tile.clone()
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mCSimple = ct.from_dlpack(c_simple_tensor) # No mark_layout_dynamic!
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print(f' hd={hd}, s_k={s_k} ({n_kv_tiles} KV tiles, pv_n_tile={pv_n_tile}, n_pv_tiles={n_pv_tiles}): Compiling...', flush=True)
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compiled = cute.compile(kernel, mQ, mK, mV, mC, stream, lse=mLSE, row_sums=mRS, c_simple=mCSimple)
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for nt in range(n_pv_tiles):
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v_start = nt * pv_n_tile
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v_end = v_start + pv_n_tile
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v_tile = v[:, v_start:v_end].contiguous()
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v_kernel = v_tile.unsqueeze(-1)
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c_tile = torch.zeros(m, pv_n_tile, 1, dtype=torch.bfloat16, device='cuda')
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lse_tensor.zero_()
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row_sums_tensor.zero_()
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mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
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mK = ct.from_dlpack(k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k))
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mV = ct.from_dlpack(v_kernel).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v_kernel))
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mC = ct.from_dlpack(c_tile).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c_tile))
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mLSE = ct.from_dlpack(lse_tensor).mark_layout_dynamic(leading_dim=ct.get_leading_dim(lse_tensor))
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mRS = ct.from_dlpack(row_sums_tensor).mark_layout_dynamic(leading_dim=ct.get_leading_dim(row_sums_tensor))
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mCSimple = ct.from_dlpack(c_tile) # No mark_layout_dynamic!
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compiled(mQ, mK, mV, mC, stream, lse=mLSE, row_sums=mRS, c_simple=mCSimple)
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torch.cuda.synchronize()
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c[:, v_start:v_end, :] = c_tile
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out = c[:, :, 0].float()
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if normalize:
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cos = torch.nn.functional.cosine_similarity(
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out.flatten().unsqueeze(0), ref_norm.flatten().unsqueeze(0)
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).item()
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ref = ref_norm
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else:
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cos = torch.nn.functional.cosine_similarity(
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out.flatten().unsqueeze(0), ref_unnorm.flatten().unsqueeze(0)
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).item()
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ref = ref_unnorm
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status = "PASS" if cos >= 0.99 else "FAIL"
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print(f' hd={hd}, s_k={s_k} ({n_kv_tiles} tiles): cos {cos:.6f} {status}')
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return cos
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def test():
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print("=== SMEM Accumulator FMHA: In-Kernel Multi-KV-Tile O Accumulation ===\n")
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# Single KV tile (s_k=128): should work like fmha.py
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print("--- Single KV tile (s_k=128) ---")
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test_smem_acc(64, 128)
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test_smem_acc(128, 128)
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# Multi KV tile: the SMEM accumulator approach should handle this correctly
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print("\n--- Multi KV tile (s_k=256+) ---")
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test_smem_acc(64, 256)
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test_smem_acc(64, 384)
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test_smem_acc(64, 512)
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test_smem_acc(128, 256)
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if __name__ == '__main__':
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test()
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