echo / code /flash-linear-attention /fla /ops /kda /chunk_inter.py
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Add Echo-Memory codebase used for this run (CC BY 4.0, JD Echo Team) (part 3)
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# 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
from fla.ops.utils.op import exp
from fla.utils import autotune_cache_kwargs, check_shared_mem
BK_LIST = [32, 64] if check_shared_mem() else [16, 32]
BV_LIST = [64, 128] if check_shared_mem('ampere') else [16, 32]
@triton.heuristics({
'IS_VARLEN': lambda args: args['cu_seqlens'] is not None,
})
@triton.autotune(
configs=[
triton.Config({'BK': BK, 'BV': BV}, num_warps=num_warps, num_stages=num_stages)
for BK in BK_LIST
for BV in BV_LIST
for num_warps in [2, 4, 8]
for num_stages in [2, 3, 4]
],
key=['BT'],
**autotune_cache_kwargs,
)
@triton.jit(do_not_specialize=['T'])
def chunk_kda_bwd_kernel_inter(
q,
k,
v,
g,
h,
do,
dh,
dq,
dk,
dv,
dw,
dg,
cu_seqlens,
chunk_indices,
scale,
T,
H: tl.constexpr,
K: tl.constexpr,
V: tl.constexpr,
BT: tl.constexpr,
BK: tl.constexpr,
BV: tl.constexpr,
IS_VARLEN: tl.constexpr,
):
i_k, i_t, i_bh = tl.program_id(0), tl.program_id(1), tl.program_id(2)
i_b, i_h = i_bh // H, i_bh % H
if IS_VARLEN:
i_tg = i_t
i_n, i_t = tl.load(chunk_indices + i_t * 2).to(tl.int32), tl.load(chunk_indices + i_t * 2 + 1).to(tl.int32)
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)
else:
NT = tl.cdiv(T, BT)
i_tg = i_b * NT + i_t
bos, eos = i_b * T, i_b * T + T
o_k = i_k * BK + tl.arange(0, BK)
m_k = o_k < K
q += (bos * H + i_h) * K
k += (bos * H + i_h) * K
v += (bos * H + i_h) * V
g += (bos * H + i_h) * K
h += (i_tg * H + i_h) * K*V
do += (bos * H + i_h) * V
dh += (i_tg * H + i_h) * K*V
dq += (bos * H + i_h) * K
dk += (bos * H + i_h) * K
dw += (bos * H + i_h) * K
dv += (bos * H + i_h) * V
dg += (bos * H + i_h) * K
p_g = tl.make_block_ptr(g, (T, K), (H*K, 1), (i_t * BT, i_k * BK), (BT, BK), (1, 0))
b_g = tl.load(p_g, boundary_check=(0, 1))
p_gn = g + (min(T, i_t * BT + BT) - 1) * H*K + o_k
b_gn = tl.load(p_gn, mask=m_k, other=0)
b_dq = tl.zeros([BT, BK], dtype=tl.float32)
b_dk = tl.zeros([BT, BK], dtype=tl.float32)
b_dw = tl.zeros([BT, BK], dtype=tl.float32)
b_dgk = tl.zeros([BK], dtype=tl.float32)
for i_v in range(tl.cdiv(V, BV)):
p_v = tl.make_block_ptr(v, (T, V), (H*V, 1), (i_t * BT, i_v * BV), (BT, BV), (1, 0))
p_do = tl.make_block_ptr(do, (T, V), (H*V, 1), (i_t * BT, i_v * BV), (BT, BV), (1, 0))
p_h = tl.make_block_ptr(h, (V, K), (1, V), (i_v * BV, i_k * BK), (BV, BK), (0, 1))
p_dh = tl.make_block_ptr(dh, (V, K), (1, V), (i_v * BV, i_k * BK), (BV, BK), (0, 1))
# [BT, BV]
b_v = tl.load(p_v, boundary_check=(0, 1))
b_do = tl.load(p_do, boundary_check=(0, 1))
# [BV, BK]
b_h = tl.load(p_h, boundary_check=(0, 1))
b_dh = tl.load(p_dh, boundary_check=(0, 1))
# [BK]
b_dgk += tl.sum(b_h * b_dh, axis=0)
# [BT, BK]
b_dq += tl.dot(b_do, b_h.to(b_do.dtype))
b_dk += tl.dot(b_v, b_dh.to(b_v.dtype))
p_dv = tl.make_block_ptr(dv, (T, V), (H*V, 1), (i_t * BT, i_v * BV), (BT, BV), (1, 0))
b_dv = tl.load(p_dv, boundary_check=(0, 1))
b_dw += tl.dot(b_dv.to(b_v.dtype), b_h.to(b_v.dtype))
p_dw = tl.make_block_ptr(dw, (T, K), (H*K, 1), (i_t * BT, i_k * BK), (BT, BK), (1, 0))
tl.store(p_dw, -b_dw.to(p_dw.dtype.element_ty), boundary_check=(0, 1))
b_dgk *= exp(b_gn)
b_dq *= scale
b_dq = b_dq * exp(b_g)
b_dk = b_dk * exp(b_gn[None, :] - b_g)
p_q = tl.make_block_ptr(q, (T, K), (H*K, 1), (i_t * BT, i_k * BK), (BT, BK), (1, 0))
p_k = tl.make_block_ptr(k, (T, K), (H*K, 1), (i_t * BT, i_k * BK), (BT, BK), (1, 0))
p_dq = tl.make_block_ptr(dq, (T, K), (H*K, 1), (i_t * BT, i_k * BK), (BT, BK), (1, 0))
p_dk = tl.make_block_ptr(dk, (T, K), (H*K, 1), (i_t * BT, i_k * BK), (BT, BK), (1, 0))
p_dg = tl.make_block_ptr(dg, (T, K), (H*K, 1), (i_t * BT, i_k * BK), (BT, BK), (1, 0))
b_q = tl.load(p_q, boundary_check=(0, 1))
b_k = tl.load(p_k, boundary_check=(0, 1))
b_dgk += tl.sum(b_dk * b_k, axis=0)
b_dg = b_q * b_dq - b_k * b_dk
b_dg = b_dg - tl.cumsum(b_dg, axis=0) + tl.sum(b_dg, axis=0)[None, :] + b_dgk[None, :]
tl.store(p_dq, b_dq.to(p_dq.dtype.element_ty), boundary_check=(0, 1))
tl.store(p_dk, b_dk.to(p_dk.dtype.element_ty), boundary_check=(0, 1))
tl.store(p_dg, b_dg.to(p_dg.dtype.element_ty), boundary_check=(0, 1))
def chunk_kda_bwd_dqkwg(
q: torch.Tensor,
k: torch.Tensor,
w: torch.Tensor,
v: torch.Tensor,
h: torch.Tensor,
g: torch.Tensor,
do: torch.Tensor,
dh: torch.Tensor,
dv: torch.Tensor,
scale: float | None = None,
cu_seqlens: torch.LongTensor | None = None,
chunk_size: int = 64,
):
B, T, H, K, V = *k.shape, v.shape[-1]
BT = min(chunk_size, max(16, triton.next_power_of_2(T)))
chunk_indices = prepare_chunk_indices(cu_seqlens, chunk_size) if cu_seqlens is not None else None
NT = triton.cdiv(T, BT) if cu_seqlens is None else len(chunk_indices)
dq = torch.empty_like(q, dtype=torch.float)
dk = torch.empty_like(k, dtype=torch.float)
dw = torch.empty_like(w)
dg = torch.empty_like(g)
def grid(meta): return (triton.cdiv(K, meta['BK']), NT, B * H)
chunk_kda_bwd_kernel_inter[grid](
q=q,
k=k,
v=v,
g=g,
h=h,
do=do,
dh=dh,
dq=dq,
dk=dk,
dv=dv,
dw=dw,
dg=dg,
cu_seqlens=cu_seqlens,
chunk_indices=chunk_indices,
scale=scale,
T=T,
H=H,
K=K,
V=V,
BT=BT,
)
return dq, dk, dw, dg