This commit is contained in:
josc146
2024-05-28 22:35:47 +08:00
parent 3488d22d22
commit f05a4acb04
138 changed files with 29047 additions and 334 deletions

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# -*- coding: utf-8 -*-
from .chunk_fuse import fused_chunk_based
from .parallel import parallel_based
__all__ = [
'fused_chunk_based',
'parallel_based'
]

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# -*- coding: utf-8 -*-
import torch
import triton
import triton.language as tl
from torch.cuda.amp import custom_bwd, custom_fwd
from fla.utils import contiguous
# on-the-fly computation without materializing hidden statets into HBMs
@triton.jit
def fused_chunk_based_fwd_kernel(
# B: batch_size, H: n_heads, T: seq_len, D: d_head
q, # query [B, H, L, D_head_K]
k, # key [B, H, L, D_head_V]
v, # value [B, H, L, D_head_V]
o, # output [B, H, L, D_head_V]
z, # normalizer [B, H, L, 1]
s_qk_h, # stride size: L * D_head_K
s_qk_t, # stride size: D_head_K
s_qk_d, # stride size: 1
s_vo_h, # stride size: L * D_head_V
s_vo_t, # stride size: D_head_V
s_vo_d, # stride size: 1
B, # batch size
H, # n_heads
T, # seq_len
scale, # D_head_K ** -0.5
BT: tl.constexpr, # BLOCK SIZE along the sequence dimension, a.k.a. chunk size
BK: tl.constexpr, # BLOCK SIZE along the K dimension
BV: tl.constexpr, # BLOCK SIZE along the V dimension
DK: tl.constexpr, # D_head_K
DV: tl.constexpr, # D_head_V
):
# indices
i_v, i_k, i_bh = tl.program_id(0), tl.program_id(1), tl.program_id(2)
o_i = tl.arange(0, BT)
# [BT, BT]
m_s = o_i[:, None] >= o_i[None, :]
# [BV], zero-order taylor expansion
b_h_0o = tl.zeros([BV], dtype=tl.float32)
# [BK, BV], first-order taylor expansion
b_h_1o = tl.zeros([BK, BV], dtype=tl.float32)
# [BK, BK, BV] second-order taylor expansion
b_h_2o = tl.zeros([BK*BK, BV], dtype=tl.float32)
# make block pointers
p_q = tl.make_block_ptr(q + i_bh * s_qk_h, (T, DK),
(s_qk_t, s_qk_d), (0, i_k * BK), (BT, BK), (1, 0))
p_k = tl.make_block_ptr(k + i_bh * s_qk_h, (DK, T),
(s_qk_d, s_qk_t), (i_k * BK, 0), (BK, BT), (0, 1))
p_v = tl.make_block_ptr(v + i_bh * s_vo_h, (T, DV),
(s_vo_t, s_vo_d), (0, i_v * BV), (BT, BV), (1, 0))
p_o = tl.make_block_ptr(o + (i_bh + i_k*B*H) * s_vo_h, (T, DV),
(s_vo_t, s_vo_d), (0, i_v * BV), (BT, BV), (1, 0))
p_z = z + (i_bh + i_k * B * H) * T + tl.arange(0, BT)
k_2o = tl.zeros([1, BK * BK], dtype=tl.float32)
k_1o = tl.zeros([1, BK], dtype=tl.float32)
k_0o = 0
for i in range(0, tl.cdiv(T, BT)):
# [BK, BT]
b_k = tl.load(p_k, boundary_check=(0, 1))
# [BK*BK, BT]
b_k_2o = b_k[:, None, :] * b_k[None, :, :]
b_k_2o = tl.reshape(b_k_2o, [BK * BK, BT]).to(b_k.dtype)
# [BT, BV]
b_v = tl.load(p_v, boundary_check=(0, 1))
# [BT, BK]
b_q = (tl.load(p_q, boundary_check=(0, 1)) * scale).to(b_k.dtype)
b_o = tl.zeros([BT, BV], dtype=tl.float32)
b_z = tl.zeros([BT], dtype=tl.float32)
# interchunk
# zero-order
b_o += b_h_0o
b_z += k_0o
# first-order
b_o += tl.dot(b_q, b_h_1o.to(b_q.dtype), allow_tf32=False)
b_z += tl.sum(b_q * k_1o, axis=1)
# second-order
b_q_2o = b_q[:, :, None] * b_q[:, None, :]
b_q_2o = tl.reshape(b_q_2o, [BT, BK * BK]).to(b_k.dtype)
b_o += tl.dot(b_q_2o, b_h_2o.to(b_q_2o.dtype), allow_tf32=False) * 0.5
b_z += tl.sum(b_q_2o * k_2o, axis=1) * 0.5
# update running statistics
k_1o += tl.sum(b_k, axis=1)[None, :]
k_2o += tl.sum(b_k_2o, axis=1)[None, :]
k_0o += BT
# intrachunk
# [BT, BT]
b_s = tl.dot(b_q, b_k, allow_tf32=False)
b_s = 1 + b_s + 0.5 * b_s * b_s
b_s = tl.where(m_s, b_s, 0)
b_z += tl.sum(b_s, axis=1)
b_o += tl.dot(b_s.to(b_q.dtype), b_v, allow_tf32=False)
# [TB, BV]
tl.store(p_o, b_o.to(p_o.dtype.element_ty), boundary_check=(0, 1))
tl.store(p_z, b_z.to(p_z.dtype.element_ty),
mask=(i * BT + tl.arange(0, BT)) < T)
# update hidden state
# [BK, BV]
b_h_2o = b_h_2o + tl.dot(b_k_2o.to(b_v.dtype), b_v, allow_tf32=False)
b_h_1o = b_h_1o + tl.dot(b_k, b_v, allow_tf32=False)
b_h_0o = b_h_0o + tl.sum(b_v, axis=0)
p_q = tl.advance(p_q, (BT, 0))
p_k = tl.advance(p_k, (0, BT))
p_v = tl.advance(p_v, (BT, 0))
p_o = tl.advance(p_o, (BT, 0))
p_z += BT
# Similar to Algorithm1 of https://arxiv.org/abs/2006.16236
@triton.jit
def fused_chunk_based_bwd_kernel(
# B: batch_size, H: n_heads, T: seq_len, D: d_head
# NV: number of split in the V dimension. NK: number of split in the K dimension
q, # query [B, H, L, D_head_K]
k, # key [B, H, L, D_head_V]
v, # value [B, H, L, D_head_V]
do, # gradient of output [B, H, L, D_head_V]
dz, # gradient of normalizer [B, H, L]
dq, # gradient of query [NV, B, H, L, D_head_K]
dk, # gradient of key [NV, B, H, L, D_head_K]
dv, # gradient of value [NK, B, H, L, D_head_V]
s_qk_h, # stride size: L * D_head_K
s_qk_t, # stride size: D_head_K
s_qk_d, # stride size: 1
s_vo_h, # stride size: L * D_head_V
s_vo_t, # stride size: D_head_V
s_vo_d, # stride size: 1
B, # batch_size
H, # n_heads
T, # seq_len
scale, # D_head_K ** -0.5
BT: tl.constexpr, # BLOCK SIZE along the sequence dimension, a.k.a. chunk size
BK: tl.constexpr, # BLOCK SIZE along the K dimension
BV: tl.constexpr, # BLOCK SIZE along the V dimension
DK: tl.constexpr, # D_head_K
DV: tl.constexpr, # D_head_V
):
i_v, i_k, i_bh = tl.program_id(0), tl.program_id(1), tl.program_id(2)
o_i = tl.arange(0, BT)
m_s = o_i[:, None] >= o_i[None, :]
# [BV], zero-order taylor expansion
# b_h_0o = tl.zeros([BV], dtype=tl.float32)
# [BK, BV], first-order taylor expansion
b_h_1o = tl.zeros([BV, BK], dtype=tl.float32)
# [BK, BK, BV] second-order taylor expansion
b_h_2o = tl.zeros([BV, BK*BK], dtype=tl.float32)
k_1o = tl.zeros([1, BK], dtype=tl.float32)
k_2o = tl.zeros([1, BK * BK], dtype=tl.float32)
for i in range(0, tl.cdiv(T, BT)):
p_q = tl.make_block_ptr(
q + i_bh * s_qk_h, (T, DK), (s_qk_t, s_qk_d), (i * BT, i_k * BK), (BT, BK), (1, 0))
p_k = tl.make_block_ptr(
k + i_bh * s_qk_h, (T, DK), (s_qk_t, s_qk_d), (i * BT, i_k * BK), (BT, BK), (1, 0))
p_v = tl.make_block_ptr(
v + i_bh * s_vo_h, (DV, T), (s_vo_d, s_vo_t), (i_v * BV, i * BT), (BV, BT), (0, 1))
p_do = tl.make_block_ptr(
do + i_bh * s_vo_h, (T, DV), (s_vo_t, s_vo_d), (i * BT, i_v * BV), (BT, BV), (1, 0))
p_dq = tl.make_block_ptr(dq + (i_bh + i_v*B*H) * s_qk_h,
(T, DK), (s_qk_t, s_qk_d), (i*BT, i_k*BK), (BT, BK), (1, 0))
p_dz = dz + (i_bh) * T + tl.arange(0, BT) + i * BT
b_dq = tl.zeros([BT, BK], dtype=tl.float32)
# load tensors
# [BT, BK]
b_dz = tl.load(p_dz, mask=(tl.arange(0, BT) + i * BT) < T)
b_q = tl.load(p_q, boundary_check=(0, 1))
b_q = (b_q * scale).to(b_q.dtype)
b_do = tl.load(p_do, boundary_check=(0, 1)).to(b_q.dtype)
b_k = tl.load(p_k, boundary_check=(0, 1))
# [BV, BT]
b_v = tl.load(p_v, boundary_check=(0, 1))
# inter-chunk
b_dq += tl.dot(b_do, (b_h_1o).to(b_do.dtype), allow_tf32=False)
if i_v == 0:
b_dq += b_dz[:, None] * k_1o
b_dq_2o = tl.dot(b_do, (b_h_2o).to(b_do.dtype), allow_tf32=False) * 0.5
if i_v == 0:
b_dq_2o += (b_dz[:, None] * k_2o) * 0.5
b_dq_2o = tl.reshape(b_dq_2o, [BT, BK, BK])
b_dq += tl.sum(b_dq_2o * b_q[:, :, None], axis=1)
b_dq += tl.sum(b_dq_2o * b_q[:, None, :], axis=2)
b_dq *= scale
# intra-chunk
# [BT, BT]
b_ds = tl.dot(b_do, b_v, allow_tf32=False)
if i_v == 0:
b_ds += b_dz[:, None]
b_ds = tl.where(m_s, b_ds, 0) * scale
b_s = tl.dot(b_q, tl.trans(b_k), allow_tf32=False)
b_s = tl.where(m_s, b_s, 0)
b_dq += tl.dot((b_ds * (1 + b_s)).to(b_q.dtype), b_k, allow_tf32=False)
# store
tl.store(p_dq, b_dq.to(p_dq.dtype.element_ty), boundary_check=(0, 1))
# update hidden state
# [BT, BK*BK]
b_k_2o = b_k[:, :, None] * b_k[:, None, :]
b_k_2o = tl.reshape(b_k_2o, [BT, BK * BK]).to(b_k.dtype)
# [BV, BK*BK]
b_h_2o = b_h_2o + tl.dot(b_v, b_k_2o.to(b_v.dtype), allow_tf32=False)
# [BV, BK]
b_h_1o = b_h_1o + tl.dot(b_v, b_k, allow_tf32=False)
if i_v == 0:
# update running statistics
k_1o += tl.sum(b_k, axis=0)[None, :]
k_2o += tl.sum(b_k_2o, axis=0)[None, :]
tl.debug_barrier()
b_h_1o = None
b_h_2o = None
# [BK, BV], first-order taylor expansion
b_dh_1o = tl.zeros([BK, BV], dtype=tl.float32)
# [BK, BK, BV] second-order taylor expansion
b_dh_2o = tl.zeros([BK*BK, BV], dtype=tl.float32)
b_dh_0o = tl.zeros([BV], dtype=tl.float32)
m_s = tl.arange(0, BT)[:, None] <= tl.arange(0, BT)[None, :]
dq_1o = tl.zeros([1, BK], dtype=tl.float32)
dq_2o = tl.zeros([BK * BK, 1], dtype=tl.float32)
for i in range(tl.cdiv(T, BT) * BT - BT, -BT, -BT):
p_q = tl.make_block_ptr(
q + i_bh * s_qk_h, (DK, T), (s_qk_d, s_qk_t), (i_k * BK, i), (BK, BT), (0, 1))
p_k = tl.make_block_ptr(
k + i_bh * s_qk_h, (T, DK), (s_qk_t, s_qk_d), (i, i_k * BK), (BT, BK), (1, 0))
p_v = tl.make_block_ptr(
v + i_bh * s_vo_h, (T, DV), (s_vo_t, s_vo_d), (i, i_v * BV), (BT, BV), (1, 0))
p_do = tl.make_block_ptr(
do + i_bh * s_vo_h, (T, DV), (s_vo_t, s_vo_d), (i, i_v * BV), (BT, BV), (1, 0))
p_dk = tl.make_block_ptr(dk + (i_bh+i_v*B*H) * s_qk_h, (T, DK),
(s_qk_t, s_qk_d), (i, i_k*BK), (BT, BK), (1, 0))
p_dv = tl.make_block_ptr(dv + (i_bh+i_k*B*H) * s_vo_h, (T, DV),
(s_vo_t, s_vo_d), (i, i_v*BV), (BT, BV), (1, 0))
p_dz = dz + (i_bh) * T + tl.arange(0, BT) + i
b_dk = tl.zeros([BT, BK], dtype=tl.float32)
b_dv = tl.zeros([BT, BV], dtype=tl.float32)
b_dz = tl.load(p_dz, mask=(tl.arange(0, BT)+i) < T)
b_q = tl.load(p_q, boundary_check=(0, 1))
b_k = tl.load(p_k, boundary_check=(0, 1))
b_v = tl.load(p_v, boundary_check=(0, 1))
b_do = tl.load(p_do, boundary_check=(0, 1)).to(b_q.dtype)
b_q = (b_q * scale).to(b_k.dtype)
# intra chunk
b_ds = tl.dot(b_v, tl.trans(b_do), allow_tf32=False)
if i_v == 0:
b_ds += b_dz[None, :]
b_ds = tl.where(m_s, b_ds, 0)
b_s = tl.dot(b_k, b_q, allow_tf32=False)
b_s2 = 1 + b_s + 0.5 * b_s * b_s
b_s = tl.where(m_s, b_s, 0)
b_s2 = tl.where(m_s, b_s2, 0)
b_ds *= (1+b_s)
b_dk += tl.dot(b_ds.to(b_k.dtype), tl.trans(b_q), allow_tf32=False)
b_dv += tl.dot(b_s2.to(b_do.dtype), b_do, allow_tf32=False)
# inter chunk
b_k_2o = b_k[:, :, None] * b_k[:, None, :]
b_k_2o = tl.reshape(b_k_2o, [BT, BK * BK]).to(b_k.dtype)
b_dv += tl.dot(b_k, b_dh_1o.to(b_k.dtype), allow_tf32=False)
b_dv += tl.dot(b_k_2o, b_dh_2o.to(b_k.dtype), allow_tf32=False)
b_dv += b_dh_0o
b_dk += tl.dot(b_v, tl.trans(b_dh_1o).to(b_k.dtype), allow_tf32=False)
if i_v == 0:
b_dk += dq_1o
b_dk_2o = tl.dot(b_dh_2o.to(b_k.dtype),
tl.trans(b_v), allow_tf32=False)
if i_v == 0:
b_dk_2o += dq_2o
b_dk_2o = tl.reshape(b_dk_2o, [BK, BK, BT])
b_k_fp32 = tl.trans(b_k.to(tl.float32))
b_dk2 = tl.sum(b_dk_2o * b_k_fp32[:, None, :], axis=0)
b_dk2 += tl.sum(b_dk_2o * b_k_fp32[None, :, :], axis=1)
b_dk += tl.trans(b_dk2)
# hidden state update
b_dh_0o += tl.sum(b_do, axis=0)
b_dh_1o = b_dh_1o + tl.dot(b_q, b_do, allow_tf32=False)
b_q_2o = b_q[None, :, :] * b_q[:, None, :]
b_q_2o = tl.reshape(b_q_2o, [BK * BK, BT]).to(b_k.dtype)
b_dh_2o = b_dh_2o + tl.dot(b_q_2o, b_do, allow_tf32=False) * 0.5
if i_v == 0:
dq_1o += (tl.sum(b_dz[None, :] * b_q, axis=1))[None, :]
dq_2o += (tl.sum(b_dz[None, :] * b_q_2o, axis=1) * 0.5)[:, None]
tl.store(p_dk, b_dk.to(p_dk.dtype.element_ty), boundary_check=(0, 1))
tl.store(p_dv, b_dv.to(p_dv.dtype.element_ty), boundary_check=(0, 1))
class FusedChunkBasedFunction(torch.autograd.Function):
@staticmethod
@contiguous
@custom_fwd
def forward(ctx, q, k, v, scale=1):
batch_size, n_heads, seq_len, d_head_qk = q.shape
# assert d_head_qk == 16, "currently we do not support feature dim other than 16"
d_head_v = v.shape[-1]
scale = scale
BT = 16
BK, BV = min(d_head_qk, 16), min(d_head_v, 32)
BK, BV = max(BK, 16), max(BV, 16)
NK, NV = triton.cdiv(d_head_qk, BK), triton.cdiv(d_head_v, BV)
num_warps = 4
# the norm of o might explode, so we need to use float32 here
o = q.new_empty(NK, batch_size, n_heads, seq_len,
d_head_v, dtype=torch.float32)
z = q.new_empty(NK, batch_size, n_heads, seq_len, dtype=torch.float32)
grid = (NV, NK, batch_size * n_heads)
fused_chunk_based_fwd_kernel[grid](
q, k, v, o, z,
q.stride(1), q.stride(2), q.stride(3),
v.stride(1), v.stride(2), v.stride(3),
batch_size, n_heads, seq_len, scale,
BT=BT, DK=d_head_qk, DV=d_head_v, BK=BK, BV=BV,
num_warps=num_warps,
)
o = o.sum(0)
z = z.sum(0)
ctx.save_for_backward(q, k, v)
ctx.scale = scale
return o.to(q.dtype), z.to(z.dtype)
@staticmethod
@contiguous
@custom_bwd
def backward(ctx, do, dz):
q, k, v = ctx.saved_tensors
batch_size, n_heads, seq_len, d_head_qk = q.shape
d_head_v = v.shape[-1]
scale = ctx.scale
BT = 16
BK, BV = min(d_head_qk, 16), min(d_head_v, 32)
BK, BV = max(BK, 16), max(BV, 16)
NK, NV = triton.cdiv(d_head_qk, BK), triton.cdiv(d_head_v, BV)
num_stages = 1
num_warps = 4
dq = q.new_empty(NV, batch_size, n_heads, seq_len, d_head_qk)
dk = q.new_empty(NV, batch_size, n_heads, seq_len, d_head_qk)
dv = q.new_empty(NK, batch_size, n_heads, seq_len, d_head_v)
grid = (NV, NK, batch_size * n_heads)
fused_chunk_based_bwd_kernel[grid](
q, k, v, do, dz, dq, dk, dv,
q.stride(1), q.stride(2), q.stride(3),
v.stride(1), v.stride(2), v.stride(3),
batch_size, n_heads, seq_len, scale,
BT=BT, DK=d_head_qk, DV=d_head_v, BK=BK, BV=BV,
num_warps=num_warps,
num_stages=num_stages
)
dq = dq.sum(0)
dk = dk.sum(0)
dv = dv.sum(0)
return dq.to(q.dtype), dk.to(k.dtype), dv.to(v.dtype), None
triton_fused_chunk_based = FusedChunkBasedFunction.apply
def fused_chunk_based(q, k, v, use_scale=True, use_normalize=True):
assert q.shape[-1] <= 16, 'only support feature dimension up to 16.'
if use_scale:
scale = q.shape[-1] ** -0.5
else:
scale = 1
o, z = triton_fused_chunk_based(q, k, v, scale)
if use_normalize:
o = o / (z[..., None] + 1e-6)
else:
o = o
return o.to(q.dtype)

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finetune/lora/v6/fla/ops/based/naive.py vendored Normal file
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# -*- coding: utf-8 -*-
import torch
from einops import rearrange
from fla.ops.based.chunk_fuse import fused_chunk_based
from fla.ops.based.parallel import parallel_based
def naive_parallel_based(q, k, v, use_scale=True, use_norm=True):
if use_scale:
q = q * (q.shape[-1] ** -0.5)
attn = q @ k.transpose(-2, -1)
attn = 1 + attn + 1/2 * (attn ** 2)
attn.masked_fill_(~torch.tril(torch.ones(
q.shape[-2], q.shape[-2], dtype=torch.bool, device=q.device)), 0)
o = attn @ v
if use_norm:
z = attn.sum(-1)
return o / (z[..., None] + 1e-6)
else:
return o
def naive_chunk_based(q, k, v, chunk_size=256):
q = q * (q.shape[-1] ** -0.5)
# compute normalizer.
k_cumsum = torch.cumsum(k, dim=-2)
kk_cumsum = torch.cumsum(k.unsqueeze(-1) * k.unsqueeze(-2), dim=-3)
# first
z = (q * k_cumsum).sum(-1)
# second order
z += (q.unsqueeze(-1) * q.unsqueeze(-2) * kk_cumsum).sum((-1, -2)) * 0.5
# zero-th order
z += (torch.arange(0, q.shape[-2]).to(z.device) * 1.0 + 1.0)[None, None, :]
# compute o
# constant term
_o = v.cumsum(-2)
q = rearrange(q, 'b h (n c) d -> b h n c d', c=chunk_size)
k = rearrange(k, 'b h (n c) d -> b h n c d', c=chunk_size)
v = rearrange(v, 'b h (n c) d -> b h n c d', c=chunk_size)
intra_chunk_attn = q @ k.transpose(-2, -1)
intra_chunk_attn = intra_chunk_attn + 1/2 * (intra_chunk_attn ** 2)
intra_chunk_attn.masked_fill_(
~torch.tril(
torch.ones(chunk_size, chunk_size,
dtype=torch.bool, device=q.device),
), 0)
o = intra_chunk_attn @ v
# quadractic term
kv = torch.einsum(
'b h n c x, b h n c y, b h n c z -> b h n x y z', k, k, v)
kv = kv.cumsum(2)
kv = torch.cat([torch.zeros_like(kv[:, :, :1]), kv[:, :, :-1]], dim=2)
o += 0.5 * torch.einsum('b h n x y z, b h n c x, b h n c y -> b h n c z', kv, q, q)
# linear term
kv = torch.einsum('b h n c x, b h n c y -> b h n x y', k, v)
kv = kv.cumsum(2)
kv = torch.cat([torch.zeros_like(kv[:, :, :1]), kv[:, :, :-1]], dim=2)
o += torch.einsum('b h n x y, b h n c x -> b h n c y', kv, q)
o = rearrange(o, 'b h n c d -> b h (n c) d')
o = o + _o
return o / (z[..., None] + 1e-6)
if __name__ == "__main__":
B = 4
H = 4
L = 128
# D = 15
dtype = torch.float32
q = (torch.randn(B, H, L, 16).cuda().to(dtype)).requires_grad_(True)
k = (torch.randn(B, H, L, 16).cuda().to(dtype)).requires_grad_(True)
v = torch.randn(B, H, L, 128).cuda().to(dtype).requires_grad_(True)
do = torch.randn_like(v).cuda()
ref = naive_parallel_based(q, k, v, True, True)
ref.backward(do, retain_graph=True)
ref_dq, q.grad = q.grad.clone(), None
ref_dk, k.grad = k.grad.clone(), None
ref_dv, v.grad = v.grad.clone(), None
# tri = naive_chunk_based(q, k, v)
# tri.backward(do, retain_graph=True)
# tri_dq, q.grad = q.grad.clone(), None
# tri_dk, k.grad = k.grad.clone(), None
# tri_dv, v.grad = v.grad.clone(), None
# assert ref.allclose(tri, 0, 1e-4), breakpoint()
# assert ref_dq.allclose(tri_dq, 0, 1e-4), breakpoint()
# assert ref_dk.allclose(tri_dk, 0, 1e-4), breakpoint()
# assert ref_dv.allclose(tri_dv, 0, 1e-4), breakpoint()
tri = fused_chunk_based(q, k, v, True, True)
tri.backward(do, retain_graph=True)
tri_dq, q.grad = q.grad.clone(), None
tri_dk, k.grad = k.grad.clone(), None
tri_dv, v.grad = v.grad.clone(), None
print((ref-tri).abs().max())
print((ref_dq-tri_dq).abs().max())
print((ref_dk-tri_dk).abs().max())
print((ref_dv-tri_dv).abs().max())
# assert ref.allclose(tri, 0, 1e-4), breakpoint()
# assert ref_dq.allclose(tri_dq, 0, 1e-4), breakpoint()
# assert ref_dk.allclose(tri_dk, 0, 1e-4), breakpoint()
# assert ref_dv.allclose(tri_dv, 0, 1e-4), breakpoint()
tri = parallel_based(q, k, v, True, True)
tri.backward(do, retain_graph=True)
tri_dq, q.grad = q.grad.clone(), None
tri_dk, k.grad = k.grad.clone(), None
tri_dv, v.grad = v.grad.clone(), None
print((ref-tri).abs().max())
print((ref_dq-tri_dq).abs().max())
print((ref_dk-tri_dk).abs().max())
print((ref_dv-tri_dv).abs().max())
# assert ref.allclose(tri, 0, 1e-4), breakpoint()
# assert ref_dq.allclose(tri_dq, 0, 1e-4), breakpoint()
# assert ref_dk.allclose(tri_dk, 0, 1e-4), breakpoint()
# assert ref_dv.allclose(tri_dv, 0, 1e-4), breakpoint()

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# -*- coding: utf-8 -*-
import torch
import triton
import triton.language as tl
from torch.cuda.amp import custom_bwd, custom_fwd
from fla.utils import contiguous
# Based: An Educational and Effective Sequence Mixer
# https://hazyresearch.stanford.edu/blog/2023-12-11-zoology2-based
@triton.jit
def parallel_based_fwd_kernel(
# B: batch_size, H: n_heads, T: seq_len, D: d_head
q, # query [B, H, L, D_head_K]
k, # key [B, H, L, D_head_V]
v, # value [B, H, L, D_head_V]
o, # output [B, H, L, D_head_V]
z, # normalizer [B, H, L]
s_qk_h, # stride size: L * D_head_K
s_qk_t, # stride size: D_head_K
s_qk_d, # stride size: 1
s_vo_h, # stride size: L * D_head_V
s_vo_t, # stride size: D_head_V
s_vo_d, # stride size: 1
B, # batch size
H, # n_heads
T, # seq_len
scale, # D_head_K ** -0.5
BTL: tl.constexpr, # BLOCK SIZE along the sequence dimension for Q
BTS: tl.constexpr, # BLOCK SIZE along the sequence dimension for K/V
BK: tl.constexpr, # BLOCK SIZE along the K dimension
BV: tl.constexpr, # BLOCK SIZE along the V dimension
DK: tl.constexpr, # D_head_K
DV: tl.constexpr, # D_head_V
):
# i_c: chunk index. used for sequence parallelism
i_kv, i_c, i_bh = tl.program_id(0), tl.program_id(1), tl.program_id(2)
NV = tl.cdiv(DV, BV)
i_k = i_kv // (NV)
i_v = i_kv % (NV)
p_q = tl.make_block_ptr(q + i_bh * s_qk_h, (T, DK),
(s_qk_t, s_qk_d), (i_c * BTL, i_k * BK), (BTL, BK), (1, 0))
p_k = tl.make_block_ptr(k + i_bh * s_qk_h, (DK, T),
(s_qk_d, s_qk_t), (i_k * BK, 0), (BK, BTS), (0, 1))
p_v = tl.make_block_ptr(v + i_bh * s_vo_h, (T, DV),
(s_vo_t, s_vo_d), (0, i_v * BV), (BTS, BV), (1, 0))
# [BQ, BD] block Q, in the shared memory throughout the whole kernel
b_q = tl.load(p_q, boundary_check=(0, 1))
b_q = (b_q * scale).to(b_q.dtype)
b_o = tl.zeros([BTL, BV], dtype=tl.float32)
b_z = tl.zeros([BTL], dtype=tl.float32)
# Q block and K block have no overlap
# no need for mask, thereby saving flops
for _ in range(0, i_c * BTL, BTS):
# [BK, BTS]
b_k = tl.load(p_k, boundary_check=(0, 1))
# [BTS, BV]
b_v = tl.load(p_v, boundary_check=(0, 1))
# [BTL, BTS]
b_s = tl.dot(b_q, (b_k), allow_tf32=False)
b_s = 1 + b_s + 0.5 * b_s * b_s
b_z += tl.sum(b_s, axis=1)
# [BQ, BD]
b_o = b_o + tl.dot(b_s.to(b_v.dtype), b_v, allow_tf32=False)
p_k = tl.advance(p_k, (0, BTS))
p_v = tl.advance(p_v, (BTS, 0))
# # rescale interchunk output
tl.debug_barrier()
o_q = tl.arange(0, BTL)
# # sync threads, easy for compiler to optimize
# tl.debug_barrier()
o_k = tl.arange(0, BTS)
p_k = tl.make_block_ptr(k + i_bh * s_qk_h, (DK, T),
(s_qk_d, s_qk_t), (i_k * BK, i_c * BTL), (BK, BTS), (0, 1))
p_v = tl.make_block_ptr(v + i_bh * s_vo_h, (T, DV),
(s_vo_t, s_vo_d), (i_c * BTL, i_v * BV), (BTS, BV), (1, 0))
# Q block and K block have overlap. masks required
for _ in range(i_c * BTL, (i_c + 1) * BTL, BTS):
# [BK, BTS]
b_k = tl.load(p_k, boundary_check=(0, 1))
# [BTS, BV]
b_v = tl.load(p_v, boundary_check=(0, 1))
# [BTL, BTS]
m_s = o_q[:, None] >= o_k[None, :]
b_s = tl.dot(b_q, b_k, allow_tf32=False)
b_s = 1 + b_s + 0.5 * b_s * b_s
b_s = tl.where(m_s, b_s, 0)
b_z += tl.sum(b_s, axis=1)
# [BTL, BV]
b_o += tl.dot(b_s.to(b_q.dtype), b_v, allow_tf32=False)
p_k = tl.advance(p_k, (0, BTS))
p_v = tl.advance(p_v, (BTS, 0))
o_k += BTS
p_o = tl.make_block_ptr(o + (i_bh + B * H * i_k) * s_vo_h, (T, DV),
(s_vo_t, s_vo_d), (i_c*BTL, i_v*BV), (BTL, BV), (1, 0))
p_z = z + (i_bh + B * H * i_k) * T + i_c * BTL + tl.arange(0, BTL)
tl.store(p_o, b_o.to(p_o.dtype.element_ty), boundary_check=(0, 1))
tl.store(p_z, b_z.to(p_z.dtype.element_ty),
mask=((i_c * BTL + tl.arange(0, BTL)) < T))
@triton.jit
def _parallel_based_bwd_dq(
i_bh, i_c, i_k, i_v, i_h,
q, k, v, do, dz, dq, s_qk_h, s_qk_t, s_qk_d, s_vo_h,
s_vo_t, s_vo_d, B, H, T, scale,
BTL: tl.constexpr, BTS: tl.constexpr, BK: tl.constexpr, BV: tl.constexpr,
DK: tl.constexpr, DV: tl.constexpr,
):
p_do = tl.make_block_ptr(do + i_bh * s_vo_h, (T, DV), (s_vo_t, s_vo_d),
(i_c * BTL, i_v * BV), (BTL, BV), (1, 0))
p_q = tl.make_block_ptr(q + (i_bh) * s_qk_h, (T, DK),
(s_qk_t, s_qk_d), (i_c*BTL, i_k*BK), (BTL, BK), (1, 0))
b_q = tl.load(p_q, boundary_check=(0, 1))
b_do = tl.load(p_do, boundary_check=(0, 1)).to(b_q.dtype)
b_q = (b_q * scale).to(b_q.dtype)
b_dq = tl.zeros([BTL, BK], dtype=tl.float32)
p_k = tl.make_block_ptr(k + i_bh * s_qk_h, (T, DK),
(s_qk_t, s_qk_d), (0, i_k * BK), (BTS, BK), (1, 0))
p_v = tl.make_block_ptr(v + i_bh * s_vo_h, (DV, T),
(s_vo_d, s_vo_t), (i_v * BV, 0), (BV, BTS), (0, 1))
p_dz = dz + i_bh * T + i_c * BTL + tl.arange(0, BTL)
b_dz = tl.load(p_dz, mask=(i_c * BTL + tl.arange(0, BTL)) < T)
for _ in range(0, i_c * BTL, BTS):
# [BTS, BK]
b_k = tl.load(p_k, boundary_check=(0, 1))
# [BV, BTS]
b_v = tl.load(p_v, boundary_check=(0, 1))
# [BTL, BTS]
b_ds = tl.dot(b_do, b_v, allow_tf32=False)
if i_v == 0:
b_ds += b_dz[:, None]
else:
b_ds = b_ds
b_s = tl.dot(b_q, tl.trans(b_k), allow_tf32=False)
# [BQ, BD]
b_dq += tl.dot((b_ds * (1 + b_s)).to(b_v.dtype), b_k, allow_tf32=False)
p_k = tl.advance(p_k, (BTS, 0))
p_v = tl.advance(p_v, (0, BTS))
b_dq *= scale
o_q = tl.arange(0, BTL)
o_k = tl.arange(0, BTS)
p_k = tl.make_block_ptr(k + i_bh * s_qk_h, (T, DK),
(s_qk_t, s_qk_d), (i_c * BTL, i_k * BK), (BTS, BK), (1, 0))
p_v = tl.make_block_ptr(v + i_bh * s_vo_h, (DV, T),
(s_vo_d, s_vo_t), (i_v * BV, i_c * BTL), (BV, BTS), (0, 1))
# Q block and K block have overlap. masks required
for _ in range(i_c * BTL, (i_c + 1) * BTL, BTS):
# [BTS, BK]
b_k = tl.load(p_k, boundary_check=(0, 1))
# [BV, BTS]
b_v = tl.load(p_v, boundary_check=(0, 1))
# [BTL, BTS]
m_s = o_q[:, None] >= o_k[None, :]
b_ds = tl.dot(b_do, b_v, allow_tf32=False)
if i_v == 0:
b_ds += b_dz[:, None]
else:
b_ds = b_ds
b_ds = tl.where(m_s, b_ds, 0) * scale
b_s = tl.dot(b_q, tl.trans(b_k), allow_tf32=False)
b_s = tl.where(m_s, b_s, 0)
# [BTL, BK]
b_dq += tl.dot((b_ds + b_ds * b_s).to(b_k.dtype),
b_k, allow_tf32=False)
p_k = tl.advance(p_k, (BTS, 0))
p_v = tl.advance(p_v, (0, BTS))
o_k += BTS
p_dq = tl.make_block_ptr(dq + (i_bh + B * H * i_v) * s_qk_h, (T, DK),
(s_qk_t, s_qk_d), (i_c*BTL, i_k*BK), (BTL, BK), (1, 0))
tl.store(p_dq, b_dq.to(p_dq.dtype.element_ty), boundary_check=(0, 1))
return
@triton.jit
def _parallel_based_bwd_dkv(
i_bh, i_c, i_k, i_v, i_h,
q, k, v, do, dz, dk, dv, s_qk_h, s_qk_t, s_qk_d, s_vo_h,
s_vo_t, s_vo_d, B, H, T, scale,
BTL: tl.constexpr, BTS: tl.constexpr, BK: tl.constexpr, BV: tl.constexpr,
DK: tl.constexpr, DV: tl.constexpr,
):
# compute dk dv
p_k = tl.make_block_ptr(k + i_bh * s_qk_h, (T, DK), (s_qk_t, s_qk_d),
(i_c * BTL, i_k * BK), (BTL, BK), (1, 0))
p_v = tl.make_block_ptr(v + i_bh * s_vo_h, (T, DV), (s_vo_t, s_vo_d),
(i_c * BTL, i_v * BV), (BTL, BV), (1, 0))
b_k, b_v = tl.load(p_k, boundary_check=(0, 1)), tl.load(
p_v, boundary_check=(0, 1))
b_dk, b_dv = tl.zeros([BTL, BK], dtype=tl.float32), tl.zeros(
[BTL, BV], dtype=tl.float32)
for i in range((tl.cdiv(T, BTS) * BTS)-BTS, (i_c + 1) * BTL - BTS, -BTS):
p_q = tl.make_block_ptr(
q + i_bh * s_qk_h, (DK, T), (s_qk_d, s_qk_t), (i_k * BK, i), (BK, BTS), (0, 1))
p_do = tl.make_block_ptr(
do + i_bh * s_vo_h, (DV, T), (s_vo_d, s_vo_t), (i_v * BV, i), (BV, BTS), (0, 1))
p_dz = dz + i_bh * T + i + tl.arange(0, BTS)
b_q = tl.load(p_q, boundary_check=(0, 1)) # [BK, BTS]
b_do = tl.load(p_do, boundary_check=(0, 1)).to(b_q.dtype) # [BV, BTS]
b_dz = tl.load(p_dz, mask=(i + tl.arange(0, BTS)) < T)
b_s = tl.dot(b_k.to(b_q.dtype), b_q, allow_tf32=False) * \
scale # [BTL, BTS]
b_s2 = 1 + b_s + 0.5 * b_s * b_s
b_dv += tl.dot(b_s2.to(b_q.dtype), tl.trans(b_do), allow_tf32=False)
b_ds = tl.dot(b_v, b_do, allow_tf32=False) * scale
if i_v == 0:
b_ds += b_dz[None, :] * scale
else:
b_ds = b_ds
b_dk += tl.dot((b_ds + b_ds * b_s).to(b_q.dtype),
tl.trans(b_q), allow_tf32=False)
tl.debug_barrier()
o_q, o_k = tl.arange(0, BTS), tl.arange(0, BTL)
for i in range(i_c*BTL, (i_c+1)*BTL, BTS):
p_q = tl.make_block_ptr(
q + i_bh * s_qk_h, (DK, T), (s_qk_d, s_qk_t), (i_k * BK, i), (BK, BTS), (0, 1))
p_do = tl.make_block_ptr(
do + i_bh * s_vo_h, (DV, T), (s_vo_d, s_vo_t), (i_v * BV, i), (BV, BTS), (0, 1))
p_dz = dz + i_bh * T + i + tl.arange(0, BTS)
b_q = tl.load(p_q, boundary_check=(0, 1)) # [BD, BQ]
b_do = tl.load(p_do, boundary_check=(0, 1)).to(b_q.dtype)
b_dz = tl.load(p_dz, mask=(i + tl.arange(0, BTS)) < T)
# [BK, BQ]
m_s = o_k[:, None] <= o_q[None, :]
b_s = tl.dot(b_k, b_q, allow_tf32=False) * scale
b_s2 = 1 + b_s + 0.5 * b_s * b_s
b_s = tl.where(m_s, b_s, 0)
b_s2 = tl.where(m_s, b_s2, 0)
b_ds = tl.dot(b_v, b_do, allow_tf32=False)
if i_v == 0:
b_ds += b_dz[None, :]
else:
b_ds = b_ds
b_ds = tl.where(m_s, b_ds, 0) * scale
# [BK, BD]
b_dv += tl.dot(b_s2.to(b_q.dtype), tl.trans(b_do), allow_tf32=False)
b_dk += tl.dot((b_ds + b_ds * b_s).to(b_q.dtype),
tl.trans(b_q), allow_tf32=False)
o_q += BTS
p_dk = tl.make_block_ptr(dk + (i_bh + B * H * i_v) * s_qk_h,
(T, DK), (s_qk_t, s_qk_d), (i_c*BTL, i_k*BK), (BTL, BK), (1, 0))
p_dv = tl.make_block_ptr(dv + (i_bh + B * H * i_k) * s_vo_h,
(T, DV), (s_vo_t, s_vo_d), (i_c*BTL, i_v*BV), (BTL, BV), (1, 0))
tl.store(p_dk, b_dk.to(p_dk.dtype.element_ty), boundary_check=(0, 1))
tl.store(p_dv, b_dv.to(p_dv.dtype.element_ty), boundary_check=(0, 1))
return
@triton.jit
def parallel_based_bwd_kernel(
q, k, v, do, dz, dq, dk, dv, s_qk_h, s_qk_t, s_qk_d, s_vo_h,
s_vo_t, s_vo_d, B, H, T, scale,
BTL: tl.constexpr, BTS: tl.constexpr, BK: tl.constexpr, BV: tl.constexpr,
DK: tl.constexpr, DV: tl.constexpr,
):
i_kv, i_c, i_bh = tl.program_id(0), tl.program_id(1), tl.program_id(2)
NV = tl.cdiv(DV, BV)
i_k = i_kv // (NV)
i_v = i_kv % (NV)
i_h = i_bh % H
_parallel_based_bwd_dq(
i_bh, i_c, i_k, i_v, i_h,
q, k, v, do, dz, dq, s_qk_h, s_qk_t, s_qk_d, s_vo_h,
s_vo_t, s_vo_d, B, H, T, scale, BTL=BTL, BTS=BTS, BK=BK, BV=BV, DK=DK, DV=DV
)
tl.debug_barrier()
_parallel_based_bwd_dkv(
i_bh, i_c, i_k, i_v, i_h,
q, k, v, do, dz, dk, dv, s_qk_h, s_qk_t, s_qk_d, s_vo_h,
s_vo_t, s_vo_d, B, H, T, scale, BTL, BTS, BK, BV, DK, DV
)
class ParallelBasedFunction(torch.autograd.Function):
@staticmethod
@contiguous
@custom_fwd
def forward(ctx, q, k, v, scale):
BTL, BTS = 128, 32
assert BTL % BTS == 0
# assert q.shape[-1] % 16 == 0
BK = min(128, triton.next_power_of_2(k.shape[-1]))
BV = min(128, triton.next_power_of_2(v.shape[-1]))
BK, BV = max(BK, 16), max(BV, 16)
batch_size, n_heads, seq_len, d_head_qk = q.shape
d_head_v = v.shape[-1]
num_stages = 2
num_warps = 4
NK = triton.cdiv(d_head_qk, BK)
NV = triton.cdiv(d_head_v, BV)
grid = (NK * NV, triton.cdiv(seq_len, BTL), batch_size * n_heads)
assert NK == 1, "will encounter some synchronization issue if not."
o = torch.empty(NK, batch_size, n_heads, seq_len,
d_head_v, device=q.device)
z = torch.empty(NK, batch_size, n_heads, seq_len,
device=q.device)
parallel_based_fwd_kernel[grid](
q, k, v, o, z,
q.stride(1), q.stride(2), q.stride(3),
v.stride(1), v.stride(2), v.stride(3),
batch_size, n_heads, seq_len, scale,
BTL=BTL, BTS=BTS, BK=BK, BV=BV, DK=d_head_qk, DV=d_head_v,
num_warps=num_warps,
num_stages=num_stages
)
ctx.save_for_backward(q, k, v)
ctx.scale = scale
return o.sum(0).to(q.dtype), z.sum(0).to(q.dtype)
@staticmethod
@custom_bwd
@contiguous
def backward(ctx, do, dz):
q, k, v = ctx.saved_tensors
scale = ctx.scale
BTL, BTS = 64, 32
assert BTL % BTS == 0
BK = min(128, triton.next_power_of_2(k.shape[-1]))
BV = min(128, triton.next_power_of_2(v.shape[-1]))
BK, BV = max(BK, 16), max(BV, 16)
batch_size, n_heads, seq_len, d_head_qk = q.shape
d_head_v = v.shape[-1]
num_stages = 2
num_warps = 4
NK = triton.cdiv(d_head_qk, BK)
NV = triton.cdiv(d_head_v, BV)
grid = (NK * NV, triton.cdiv(seq_len, BTL), batch_size * n_heads)
assert NK == 1, "will encounter some synchronization issue if not"
dq = torch.empty(NV, batch_size, n_heads, seq_len,
d_head_qk, dtype=q.dtype, device=q.device)
dk = torch.empty(NV, batch_size, n_heads, seq_len,
d_head_qk, dtype=q.dtype, device=q.device)
dv = torch.empty(NK, batch_size, n_heads, seq_len,
d_head_v, dtype=q.dtype, device=q.device)
parallel_based_bwd_kernel[grid](
q, k, v, do, dz, dq, dk, dv,
q.stride(1), q.stride(2), q.stride(3),
v.stride(1), v.stride(2), v.stride(3),
batch_size, n_heads, seq_len, scale,
BTL=BTL, BTS=BTS, BK=BK, BV=BV, DK=d_head_qk, DV=d_head_v,
num_warps=num_warps,
num_stages=num_stages
)
return dq.sum(0).to(q.dtype), dk.sum(0).to(k.dtype), dv.sum(0).to(v.dtype), None
triton_parallel_based = ParallelBasedFunction.apply
def parallel_based(q, k, v, use_scale=True, use_normalize=True, return_both=False):
assert q.shape[-1] <= 128, "only support feature dim up to 128"
if use_scale:
scale = q.shape[-1] ** -0.5
else:
scale = 1
o, z = triton_parallel_based(q, k, v, scale)
if return_both:
return o, z
if use_normalize:
o = o / (z[..., None] + 1e-6)
else:
o = o
return o.to(q.dtype)