diff --git a/dsv4/kernels/attention/fmha.py b/dsv4/kernels/attention/fmha.py index 3abd839f..d8c667c6 100644 --- a/dsv4/kernels/attention/fmha.py +++ b/dsv4/kernels/attention/fmha.py @@ -366,18 +366,40 @@ class FmhaKernel: cute.copy(tiled_tmem_store, rP_words, tTMEM_STOREtP) cute.arch.fence_view_async_tmem_store() else: - # SMEM-P: write P to sP using coordinate-indexed store. - # Uses tTMEM_LOADcS identity tensor to get (m, k) coordinates. - for j0 in range(32): - for j1 in range(4): - coord = tTMEM_LOADcS[(j0, 0), j1, 0, 0] - m_coord = coord[0] - k_coord = coord[1] - k0 = k_coord % 16 - k1 = (k_coord // 16) % 4 - k2 = k_coord // 64 - _sP_nostage[(m_coord, k0), 0, (k1, k2)] = rP_bf16[(j0, 0), j1, 0, 0] - cute.arch.fence_proxy("async.shared", space="cta") + # SMEM-P: write P to sP using make_cotiled_copy. + # Build atom_layout_tv: (tid, vid) -> sP_addr. + # Each softmax thread (128 total) owns one row of the 128×128 P matrix. + # Within a row, 128 values decompose as (k0, k1, k2) = (16, 4, 2) + # matching sP's subtiled layout strides (1, 16, 8192). + # Thread stride = 64 (one row in sP's layout). + # + # atom_layout_tv(tid, k0, k1, k2) = 64*tid + k0 + 16*k1 + 8192*k2 + # sP_addr(m, k0, k1, k2) = 64*m + k0 + 16*k1 + 8192*k2 + # These are the SAME function — tid maps to m naturally. + _smem_p_atom = cute.make_copy_atom( + cute.nvgpu.CopyUniversalOp(), + self.q_dtype, + num_bits_per_copy=16, + ) + _smem_p_atom_layout_tv = cute.make_layout( + (128, (16, 4, 2)), + stride=(64, (1, 16, 8192)), + ) + # Build sP data layout (coalesced, no swizzle, no stage dim) + # sP_outer has shape ((128,16),1,(4,2),1) with strides ((64,1),0,(16,8192),0) + # Coalesced: ((128,16,4,2),(64,1,16,8192)) + _smem_p_data_layout = cute.make_layout( + (128, 16, 4, 2), + stride=(64, 1, 16, 8192), + ) + _tiled_smem_p = cute.make_cotiled_copy( + _smem_p_atom, _smem_p_atom_layout_tv, _smem_p_data_layout, + ) + _thr_smem_p = _tiled_smem_p.get_slice(sfw_idx) + _tRS_sP = _thr_smem_p.partition_D(_sP_nostage) + _tRS_rP = _tiled_smem_p.retile(rP_bf16) + cute.copy(_tiled_smem_p, _tRS_rP, _tRS_sP) + cute.arch.fence("shared", space="cta") if kt > 0: for i in range(n_corr_tiles): tTMrO_i_ = tTMrO[None, i]