# Copyright (c) 2023-2025, Songlin Yang, Yu Zhang import torch import triton import triton.language as tl from fla.ops.utils import prepare_chunk_indices, prepare_chunk_offsets from fla.ops.utils.op import exp from fla.utils import autotune_cache_kwargs, check_shared_mem, is_nvidia_hopper, use_cuda_graph NUM_WARPS = [2, 4] if is_nvidia_hopper else [2, 4, 8, 16] @triton.heuristics({ 'USE_G': lambda args: args['g'] is not None, 'USE_GK': lambda args: args['gk'] is not None, 'USE_INITIAL_STATE': lambda args: args['h0'] is not None, 'STORE_FINAL_STATE': lambda args: args['ht'] is not None, 'SAVE_NEW_VALUE': lambda args: args['v_new'] is not None, 'IS_VARLEN': lambda args: args['cu_seqlens'] is not None, }) @triton.autotune( configs=[ triton.Config({'BV': BV}, num_warps=num_warps, num_stages=num_stages) for num_warps in [2, 4] for num_stages in [2, 3, 4] for BV in [32, 64] ], key=['H', 'K', 'V', 'BT'], use_cuda_graph=use_cuda_graph, **autotune_cache_kwargs, ) @triton.jit(do_not_specialize=['T']) def chunk_gated_delta_rule_fwd_kernel_h_blockdim64( k, v, w, v_new, g, gk, h, h0, ht, cu_seqlens, chunk_offsets, T, H: tl.constexpr, K: tl.constexpr, V: tl.constexpr, BT: tl.constexpr, BV: tl.constexpr, USE_G: tl.constexpr, USE_GK: tl.constexpr, USE_INITIAL_STATE: tl.constexpr, STORE_FINAL_STATE: tl.constexpr, SAVE_NEW_VALUE: tl.constexpr, IS_VARLEN: tl.constexpr, ): i_v, i_nh = tl.program_id(0), tl.program_id(1) i_n, i_h = i_nh // H, i_nh % H if IS_VARLEN: bos, eos = tl.load(cu_seqlens + i_n).to(tl.int32), tl.load(cu_seqlens + i_n + 1).to(tl.int32) T = eos - bos NT = tl.cdiv(T, BT) boh = tl.load(chunk_offsets + i_n).to(tl.int32) else: bos, eos = i_n * T, i_n * T + T NT = tl.cdiv(T, BT) boh = i_n * NT # [BK, BV] b_h1 = tl.zeros([64, BV], dtype=tl.float32) if K > 64: b_h2 = tl.zeros([64, BV], dtype=tl.float32) if K > 128: b_h3 = tl.zeros([64, BV], dtype=tl.float32) if K > 192: b_h4 = tl.zeros([64, BV], dtype=tl.float32) # calculate offset h += ((boh * H + i_h) * K*V).to(tl.int64) v += ((bos * H + i_h) * V).to(tl.int64) k += ((bos * H + i_h) * K).to(tl.int64) w += ((bos * H + i_h) * K).to(tl.int64) if SAVE_NEW_VALUE: v_new += ((bos * H + i_h) * V).to(tl.int64) stride_v = H*V stride_h = H*K*V stride_k = H*K if USE_INITIAL_STATE: h0 = h0 + i_nh * K*V if STORE_FINAL_STATE: ht = ht + i_nh * K*V # load initial state if USE_INITIAL_STATE: p_h0_1 = tl.make_block_ptr(h0, (K, V), (V, 1), (0, i_v * BV), (64, BV), (1, 0)) b_h1 += tl.load(p_h0_1, boundary_check=(0, 1)).to(tl.float32) if K > 64: p_h0_2 = tl.make_block_ptr(h0, (K, V), (V, 1), (64, i_v * BV), (64, BV), (1, 0)) b_h2 += tl.load(p_h0_2, boundary_check=(0, 1)).to(tl.float32) if K > 128: p_h0_3 = tl.make_block_ptr(h0, (K, V), (V, 1), (128, i_v * BV), (64, BV), (1, 0)) b_h3 += tl.load(p_h0_3, boundary_check=(0, 1)).to(tl.float32) if K > 192: p_h0_4 = tl.make_block_ptr(h0, (K, V), (V, 1), (192, i_v * BV), (64, BV), (1, 0)) b_h4 += tl.load(p_h0_4, boundary_check=(0, 1)).to(tl.float32) # main recurrence for i_t in range(NT): p_h1 = tl.make_block_ptr(h + i_t * stride_h, (K, V), (V, 1), (0, i_v * BV), (64, BV), (1, 0)) tl.store(p_h1, b_h1.to(p_h1.dtype.element_ty), boundary_check=(0, 1)) if K > 64: p_h2 = tl.make_block_ptr(h + i_t * stride_h, (K, V), (V, 1), (64, i_v * BV), (64, BV), (1, 0)) tl.store(p_h2, b_h2.to(p_h2.dtype.element_ty), boundary_check=(0, 1)) if K > 128: p_h3 = tl.make_block_ptr(h + i_t * stride_h, (K, V), (V, 1), (128, i_v * BV), (64, BV), (1, 0)) tl.store(p_h3, b_h3.to(p_h3.dtype.element_ty), boundary_check=(0, 1)) if K > 192: p_h4 = tl.make_block_ptr(h + i_t * stride_h, (K, V), (V, 1), (192, i_v * BV), (64, BV), (1, 0)) tl.store(p_h4, b_h4.to(p_h4.dtype.element_ty), boundary_check=(0, 1)) p_w = tl.make_block_ptr(w, (T, K), (stride_k, 1), (i_t * BT, 0), (BT, 64), (1, 0)) b_w = tl.load(p_w, boundary_check=(0, 1)) b_v = tl.dot(b_w, b_h1.to(b_w.dtype)) if K > 64: p_w = tl.make_block_ptr(w, (T, K), (stride_k, 1), (i_t * BT, 64), (BT, 64), (1, 0)) b_w = tl.load(p_w, boundary_check=(0, 1)) b_v += tl.dot(b_w, b_h2.to(b_w.dtype)) if K > 128: p_w = tl.make_block_ptr(w, (T, K), (stride_k, 1), (i_t * BT, 128), (BT, 64), (1, 0)) b_w = tl.load(p_w, boundary_check=(0, 1)) b_v += tl.dot(b_w, b_h3.to(b_w.dtype)) if K > 192: p_w = tl.make_block_ptr(w, (T, K), (stride_k, 1), (i_t * BT, 192), (BT, 64), (1, 0)) b_w = tl.load(p_w, boundary_check=(0, 1)) b_v += tl.dot(b_w, b_h4.to(b_w.dtype)) p_v = tl.make_block_ptr(v, (T, V), (stride_v, 1), (i_t * BT, i_v * BV), (BT, BV), (1, 0)) b_v = tl.load(p_v, boundary_check=(0, 1)) - b_v if SAVE_NEW_VALUE: p_v = tl.make_block_ptr(v_new, (T, V), (stride_v, 1), (i_t * BT, i_v * BV), (BT, BV), (1, 0)) tl.store(p_v, b_v.to(p_v.dtype.element_ty), boundary_check=(0, 1)) last_idx = min((i_t + 1) * BT, T) - 1 if USE_G: m_t = (i_t * BT + tl.arange(0, BT)) < T b_g_last = tl.load(g + bos * H + last_idx * H + i_h) p_g = tl.make_block_ptr(g + bos * H + i_h, (T,), (H,), (i_t * BT,), (BT,), (0,)) b_g = tl.load(p_g, boundary_check=(0,)) b_v = b_v * tl.where(m_t, exp(b_g_last - b_g), 0)[:, None] b_g_last = exp(b_g_last) b_h1 *= b_g_last if K > 64: b_h2 *= b_g_last if K > 128: b_h3 *= b_g_last if K > 192: b_h4 *= b_g_last if USE_GK: o_k1 = tl.arange(0, 64) b_gk_last1 = tl.load(gk + (bos + last_idx) * H*K + i_h * K + o_k1, mask=(o_k1 < K), other=0.) b_h1 *= exp(b_gk_last1)[:, None] if K > 64: o_k2 = 64 + o_k1 b_gk_last2 = tl.load(gk + (bos + last_idx) * H*K + i_h * K + o_k2, mask=(o_k2 < K), other=0.) b_h2 *= exp(b_gk_last2)[:, None] if K > 128: o_k3 = 128 + o_k1 b_gk_last3 = tl.load(gk + (bos + last_idx) * H*K + i_h * K + o_k3, mask=(o_k3 < K), other=0.) b_h3 *= exp(b_gk_last3)[:, None] if K > 192: o_k4 = 192 + o_k1 b_gk_last4 = tl.load(gk + (bos + last_idx) * H*K + i_h * K + o_k4, mask=(o_k4 < K), other=0.) b_h4 *= exp(b_gk_last4)[:, None] b_v = b_v.to(k.dtype.element_ty) p_k = tl.make_block_ptr(k, (K, T), (1, stride_k), (0, i_t * BT), (64, BT), (0, 1)) b_k = tl.load(p_k, boundary_check=(0, 1)) b_h1 += tl.dot(b_k, b_v) if K > 64: p_k = tl.make_block_ptr(k, (K, T), (1, stride_k), (64, i_t * BT), (64, BT), (0, 1)) b_k = tl.load(p_k, boundary_check=(0, 1)) b_h2 += tl.dot(b_k, b_v) if K > 128: p_k = tl.make_block_ptr(k, (K, T), (1, stride_k), (128, i_t * BT), (64, BT), (0, 1)) b_k = tl.load(p_k, boundary_check=(0, 1)) b_h3 += tl.dot(b_k, b_v) if K > 192: p_k = tl.make_block_ptr(k, (K, T), (1, stride_k), (192, i_t * BT), (64, BT), (0, 1)) b_k = tl.load(p_k, boundary_check=(0, 1)) b_h4 += tl.dot(b_k, b_v) # epilogue if STORE_FINAL_STATE: p_ht = tl.make_block_ptr(ht, (K, V), (V, 1), (0, i_v * BV), (64, BV), (1, 0)) tl.store(p_ht, b_h1.to(p_ht.dtype.element_ty), boundary_check=(0, 1)) if K > 64: p_ht = tl.make_block_ptr(ht, (K, V), (V, 1), (64, i_v * BV), (64, BV), (1, 0)) tl.store(p_ht, b_h2.to(p_ht.dtype.element_ty), boundary_check=(0, 1)) if K > 128: p_ht = tl.make_block_ptr(ht, (K, V), (V, 1), (128, i_v * BV), (64, BV), (1, 0)) tl.store(p_ht, b_h3.to(p_ht.dtype.element_ty), boundary_check=(0, 1)) if K > 192: p_ht = tl.make_block_ptr(ht, (K, V), (V, 1), (192, i_v * BV), (64, BV), (1, 0)) tl.store(p_ht, b_h4.to(p_ht.dtype.element_ty), boundary_check=(0, 1)) @triton.heuristics({ 'USE_G': lambda args: args['g'] is not None, 'USE_GK': lambda args: args['gk'] is not None, 'USE_INITIAL_STATE': lambda args: args['dh0'] is not None, 'USE_FINAL_STATE_GRADIENT': lambda args: args['dht'] is not None, 'IS_VARLEN': lambda args: args['cu_seqlens'] is not None, }) @triton.autotune( configs=[ triton.Config({'BV': BV}, num_warps=num_warps, num_stages=num_stages) for num_warps in [2, 4] for num_stages in ([4, 3, 2] if check_shared_mem('ampere') else [1]) for BV in [64, 32] ], key=['H', 'K', 'V', 'BT', 'BV', 'USE_G'], use_cuda_graph=use_cuda_graph, **autotune_cache_kwargs, ) @triton.jit(do_not_specialize=['T']) def chunk_gated_delta_rule_bwd_kernel_dhu_blockdim64( q, k, w, g, gk, dht, dh0, do, dh, dv, dv2, cu_seqlens, chunk_offsets, scale, T, H: tl.constexpr, K: tl.constexpr, V: tl.constexpr, BT: tl.constexpr, BV: tl.constexpr, USE_G: tl.constexpr, USE_GK: tl.constexpr, USE_INITIAL_STATE: tl.constexpr, USE_FINAL_STATE_GRADIENT: tl.constexpr, IS_VARLEN: tl.constexpr, ): i_v, i_nh = tl.program_id(0), tl.program_id(1) i_n, i_h = i_nh // H, i_nh % H if IS_VARLEN: bos, eos = tl.load(cu_seqlens + i_n).to(tl.int32), tl.load(cu_seqlens + i_n + 1).to(tl.int32) T = eos - bos NT = tl.cdiv(T, BT) boh = tl.load(chunk_offsets + i_n).to(tl.int32) else: bos, eos = i_n * T, i_n * T + T NT = tl.cdiv(T, BT) boh = i_n * NT # [BK, BV] b_dh1 = tl.zeros([64, BV], dtype=tl.float32) if K > 64: b_dh2 = tl.zeros([64, BV], dtype=tl.float32) if K > 128: b_dh3 = tl.zeros([64, BV], dtype=tl.float32) if K > 192: b_dh4 = tl.zeros([64, BV], dtype=tl.float32) # calculate offset q += ((bos * H + i_h) * K).to(tl.int64) k += ((bos * H + i_h) * K).to(tl.int64) w += ((bos * H + i_h) * K).to(tl.int64) do += ((bos * H + i_h) * V).to(tl.int64) dv += ((bos * H + i_h) * V).to(tl.int64) dv2 += ((bos * H + i_h) * V).to(tl.int64) dh += ((boh * H + i_h) * K*V).to(tl.int64) if USE_GK: gk += ((bos * H + i_h) * K).to(tl.int64) stride_v = H*V stride_h = H*K*V stride_k = H*K if USE_INITIAL_STATE: dh0 += i_nh * K*V if USE_FINAL_STATE_GRADIENT: dht += i_nh * K*V if USE_FINAL_STATE_GRADIENT: p_dht1 = tl.make_block_ptr(dht, (K, V), (V, 1), (0, i_v * BV), (64, BV), (1, 0)) b_dh1 += tl.load(p_dht1, boundary_check=(0, 1)) if K > 64: p_dht2 = tl.make_block_ptr(dht, (K, V), (V, 1), (64, i_v * BV), (64, BV), (1, 0)) b_dh2 += tl.load(p_dht2, boundary_check=(0, 1)) if K > 128: p_dht3 = tl.make_block_ptr(dht, (K, V), (V, 1), (128, i_v * BV), (64, BV), (1, 0)) b_dh3 += tl.load(p_dht3, boundary_check=(0, 1)) if K > 192: p_dht4 = tl.make_block_ptr(dht, (K, V), (V, 1), (192, i_v * BV), (64, BV), (1, 0)) b_dh4 += tl.load(p_dht4, boundary_check=(0, 1)) for i_t in range(NT - 1, -1, -1): p_dh1 = tl.make_block_ptr(dh + i_t*stride_h, (K, V), (V, 1), (0, i_v * BV), (64, BV), (1, 0)) tl.store(p_dh1, b_dh1.to(p_dh1.dtype.element_ty), boundary_check=(0, 1)) if K > 64: p_dh2 = tl.make_block_ptr(dh + i_t*stride_h, (K, V), (V, 1), (64, i_v * BV), (64, BV), (1, 0)) tl.store(p_dh2, b_dh2.to(p_dh2.dtype.element_ty), boundary_check=(0, 1)) if K > 128: p_dh3 = tl.make_block_ptr(dh + i_t*stride_h, (K, V), (V, 1), (128, i_v * BV), (64, BV), (1, 0)) tl.store(p_dh3, b_dh3.to(p_dh3.dtype.element_ty), boundary_check=(0, 1)) if K > 192: p_dh4 = tl.make_block_ptr(dh + i_t*stride_h, (K, V), (V, 1), (192, i_v * BV), (64, BV), (1, 0)) tl.store(p_dh4, b_dh4.to(p_dh4.dtype.element_ty), boundary_check=(0, 1)) last_idx = min((i_t + 1) * BT, T) - 1 if USE_G: bg_last = tl.load(g + (bos + last_idx) * H + i_h) bg_last_exp = exp(bg_last) p_g = tl.make_block_ptr(g + bos * H + i_h, (T,), (H,), (i_t * BT,), (BT,), (0,)) b_g = tl.load(p_g, boundary_check=(0,)) b_g_exp = exp(b_g) p_dv = tl.make_block_ptr(dv, (T, V), (stride_v, 1), (i_t * BT, i_v * BV), (BT, BV), (1, 0)) p_dv2 = tl.make_block_ptr(dv2, (T, V), (stride_v, 1), (i_t * BT, i_v * BV), (BT, BV), (1, 0)) p_do = tl.make_block_ptr(do, (T, V), (stride_v, 1), (i_t * BT, i_v * BV), (BT, BV), (1, 0)) b_do = tl.load(p_do, boundary_check=(0, 1)) # Update dv p_k = tl.make_block_ptr(k, (T, K), (stride_k, 1), (i_t * BT, 0), (BT, 64), (1, 0)) b_k = tl.load(p_k, boundary_check=(0, 1)) if USE_GK: o_k1 = tl.arange(0, 64) b_gk_last1 = tl.load(gk + last_idx * H*K + o_k1, mask=(o_k1 < K), other=0.) b_dv = tl.dot(b_k, b_dh1.to(b_k.dtype)) if K > 64: p_k = tl.make_block_ptr(k, (T, K), (stride_k, 1), (i_t * BT, 64), (BT, 64), (1, 0)) b_k = tl.load(p_k, boundary_check=(0, 1)) if USE_GK: o_k2 = 64 + o_k1 b_gk_last2 = tl.load(gk + last_idx * H*K + o_k2, mask=(o_k2 < K), other=0.) b_dv += tl.dot(b_k, b_dh2.to(b_k.dtype)) if K > 128: p_k = tl.make_block_ptr(k, (T, K), (stride_k, 1), (i_t * BT, 128), (BT, 64), (1, 0)) b_k = tl.load(p_k, boundary_check=(0, 1)) if USE_GK: o_k3 = 128 + o_k1 b_gk_last3 = tl.load(gk + last_idx * H*K + o_k3, mask=(o_k3 < K), other=0.) b_dv += tl.dot(b_k, b_dh3.to(b_k.dtype)) if K > 192: p_k = tl.make_block_ptr(k, (T, K), (stride_k, 1), (i_t * BT, 192), (BT, 64), (1, 0)) b_k = tl.load(p_k, boundary_check=(0, 1)) if USE_GK: o_k4 = 192 + o_k1 b_gk_last4 = tl.load(gk + last_idx * H*K + o_k4, mask=(o_k4 < K), other=0.) b_dv += tl.dot(b_k, b_dh4.to(b_k.dtype)) if USE_G: m_t = (i_t * BT + tl.arange(0, BT)) < T b_dv *= tl.where(m_t, exp(bg_last - b_g), 0)[:, None] b_dv += tl.load(p_dv, boundary_check=(0, 1)) tl.store(p_dv2, b_dv.to(p_dv.dtype.element_ty), boundary_check=(0, 1)) # Update dh p_w = tl.make_block_ptr(w, (K, T), (1, stride_k), (0, i_t * BT), (64, BT), (0, 1)) p_q = tl.make_block_ptr(q, (K, T), (1, stride_k), (0, i_t * BT), (64, BT), (0, 1)) b_w = tl.load(p_w, boundary_check=(0, 1)) b_q = tl.load(p_q, boundary_check=(0, 1)) if USE_G: b_dh1 *= bg_last_exp b_q = b_q * b_g_exp[None, :] if USE_GK: b_dh1 *= exp(b_gk_last1[:, None]) b_dh1 += tl.dot(b_q.to(b_q.dtype), b_do.to(b_q.dtype)) * scale - tl.dot(b_w, b_dv.to(b_w.dtype)) if K > 64: p_q = tl.make_block_ptr(q, (K, T), (1, stride_k), (64, i_t * BT), (64, BT), (0, 1)) p_w = tl.make_block_ptr(w, (K, T), (1, stride_k), (64, i_t * BT), (64, BT), (0, 1)) b_q = tl.load(p_q, boundary_check=(0, 1)) b_w = tl.load(p_w, boundary_check=(0, 1)) if USE_G: b_dh2 *= bg_last_exp b_q = b_q * b_g_exp[None, :] if USE_GK: b_dh2 *= exp(b_gk_last2[:, None]) b_dh2 += tl.dot(b_q.to(b_q.dtype), b_do.to(b_q.dtype)) * scale - tl.dot(b_w, b_dv.to(b_w.dtype)) if K > 128: p_q = tl.make_block_ptr(q, (K, T), (1, stride_k), (128, i_t * BT), (64, BT), (0, 1)) p_w = tl.make_block_ptr(w, (K, T), (1, stride_k), (128, i_t * BT), (64, BT), (0, 1)) b_q = tl.load(p_q, boundary_check=(0, 1)) b_w = tl.load(p_w, boundary_check=(0, 1)) if USE_G: b_dh3 *= bg_last_exp b_q = b_q * b_g_exp[None, :] if USE_GK: b_dh3 *= exp(b_gk_last3[:, None]) b_dh3 += tl.dot(b_q.to(b_q.dtype), b_do.to(b_q.dtype)) * scale - tl.dot(b_w, b_dv.to(b_w.dtype)) if K > 192: p_q = tl.make_block_ptr(q, (K, T), (1, stride_k), (192, i_t * BT), (64, BT), (0, 1)) p_w = tl.make_block_ptr(w, (K, T), (1, stride_k), (192, i_t * BT), (64, BT), (0, 1)) b_q = tl.load(p_q, boundary_check=(0, 1)) b_w = tl.load(p_w, boundary_check=(0, 1)) if USE_G: b_dh4 *= bg_last_exp b_q = b_q * b_g_exp[None, :] if USE_GK: b_dh4 *= exp(b_gk_last4[:, None]) b_dh4 += tl.dot(b_q.to(b_q.dtype), b_do.to(b_q.dtype)) * scale - tl.dot(b_w, b_dv.to(b_w.dtype)) if USE_INITIAL_STATE: p_dh0 = tl.make_block_ptr(dh0, (K, V), (V, 1), (0, i_v * BV), (64, BV), (1, 0)) tl.store(p_dh0, b_dh1.to(p_dh0.dtype.element_ty), boundary_check=(0, 1)) if K > 64: p_dh1 = tl.make_block_ptr(dh0, (K, V), (V, 1), (64, i_v * BV), (64, BV), (1, 0)) tl.store(p_dh1, b_dh2.to(p_dh1.dtype.element_ty), boundary_check=(0, 1)) if K > 128: p_dh2 = tl.make_block_ptr(dh0, (K, V), (V, 1), (128, i_v * BV), (64, BV), (1, 0)) tl.store(p_dh2, b_dh3.to(p_dh2.dtype.element_ty), boundary_check=(0, 1)) if K > 192: p_dh3 = tl.make_block_ptr(dh0, (K, V), (V, 1), (192, i_v * BV), (64, BV), (1, 0)) tl.store(p_dh3, b_dh4.to(p_dh3.dtype.element_ty), boundary_check=(0, 1)) def chunk_gated_delta_rule_fwd_h( k: torch.Tensor, w: torch.Tensor, u: torch.Tensor, g: torch.Tensor | None = None, gk: torch.Tensor | None = None, initial_state: torch.Tensor | None = None, output_final_state: bool = False, chunk_size: int = 64, # SY: remove this argument and force chunk size 64? save_new_value: bool = True, cu_seqlens: torch.LongTensor | None = None, ) -> tuple[torch.Tensor, torch.Tensor]: B, T, H, K, V = *k.shape, u.shape[-1] BT = chunk_size chunk_indices = prepare_chunk_indices(cu_seqlens, chunk_size) if cu_seqlens is not None else None # N: the actual number of sequences in the batch with either equal or variable lengths if cu_seqlens is None: N, NT, chunk_offsets = B, triton.cdiv(T, BT), None else: N, NT, chunk_offsets = len(cu_seqlens) - 1, len(chunk_indices), prepare_chunk_offsets(cu_seqlens, BT) assert K <= 256, "current kernel does not support head dimension larger than 256." h = k.new_empty(B, NT, H, K, V) final_state = k.new_empty(N, H, K, V, dtype=torch.float32) if output_final_state else None v_new = torch.empty_like(u) if save_new_value else None def grid(meta): return (triton.cdiv(V, meta['BV']), N*H) chunk_gated_delta_rule_fwd_kernel_h_blockdim64[grid]( k=k, v=u, w=w, v_new=v_new, g=g, gk=gk, h=h, h0=initial_state, ht=final_state, cu_seqlens=cu_seqlens, chunk_offsets=chunk_offsets, T=T, H=H, K=K, V=V, BT=BT, ) return h, v_new, final_state def chunk_gated_delta_rule_bwd_dhu( q: torch.Tensor, k: torch.Tensor, w: torch.Tensor, do: torch.Tensor, dv: torch.Tensor, g: torch.Tensor | None = None, gk: torch.Tensor | None = None, h0: torch.Tensor | None = None, dht: torch.Tensor | None = None, scale: float | None = None, cu_seqlens: torch.LongTensor | None = None, chunk_size: int = 64, # SY: remove this argument and force chunk size 64? ) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]: B, T, H, K, V = *q.shape, do.shape[-1] # N: the actual number of sequences in the batch with either equal or variable lengths BT = 64 assert K <= 256, "current kernel does not support head dimension being larger than 256." chunk_indices = prepare_chunk_indices(cu_seqlens, chunk_size) if cu_seqlens is not None else None if cu_seqlens is None: N, NT, chunk_offsets = B, triton.cdiv(T, BT), None else: N, NT, chunk_offsets = len(cu_seqlens) - 1, len(chunk_indices), prepare_chunk_offsets(cu_seqlens, BT) dh = q.new_empty(B, NT, H, K, V) dh0 = torch.empty_like(h0, dtype=torch.float32) if h0 is not None else None dv2 = torch.empty_like(dv) def grid(meta): return (triton.cdiv(V, meta['BV']), N*H) chunk_gated_delta_rule_bwd_kernel_dhu_blockdim64[grid]( q=q, k=k, w=w, g=g, gk=gk, dht=dht, dh0=dh0, do=do, dh=dh, dv=dv, dv2=dv2, cu_seqlens=cu_seqlens, chunk_offsets=chunk_offsets, scale=scale, T=T, H=H, K=K, V=V, BT=BT, ) return dh, dh0, dv2