ColossalAI/colossalai/kernel/triton/token_attention_kernel.py

334 lines
14 KiB
Python

# Adapted from ModelTC https://github.com/ModelTC/lightllm
import math
import torch
try:
import triton
import triton.language as tl
HAS_TRITON = True
except ImportError:
HAS_TRITON = False
print("please install triton from https://github.com/openai/triton")
if HAS_TRITON:
@triton.jit
def _token_attn_1_kernel(Q, K, sm_scale, kv_cache_loc, kv_cache_start_loc, kv_cache_seqlen, max_kv_cache_len,
attn_out, kv_cache_loc_b_stride, kv_cache_loc_s_stride, q_batch_stride, q_head_stride,
q_head_dim_stride, k_batch_stride, k_head_stride, k_head_dim_stride, attn_head_stride,
attn_batch_stride, HEAD_DIM: tl.constexpr, BLOCK_N: tl.constexpr):
current_batch = tl.program_id(0)
current_head = tl.program_id(1)
start_n = tl.program_id(2)
offs_d = tl.arange(0, HEAD_DIM)
current_batch_seq_len = tl.load(kv_cache_seqlen + current_batch)
current_batch_in_all_start_index = tl.load(kv_cache_start_loc + current_batch)
current_batch_start_index = max_kv_cache_len - current_batch_seq_len
current_batch_end_index = max_kv_cache_len
off_q = current_batch * q_batch_stride + current_head * q_head_stride + offs_d * q_head_dim_stride
offs_n = start_n * BLOCK_N + tl.arange(0, BLOCK_N)
block_stard_index = start_n * BLOCK_N
block_mask = tl.where(block_stard_index < current_batch_seq_len, 1, 0)
for start_mark in range(0, block_mask, 1):
q = tl.load(Q + off_q + start_mark)
offs_n_new = current_batch_start_index + offs_n
k_loc = tl.load(kv_cache_loc + kv_cache_loc_b_stride * current_batch + kv_cache_loc_s_stride * offs_n_new,
mask=offs_n_new < current_batch_end_index,
other=0)
off_k = k_loc[:, None] * k_batch_stride + current_head * k_head_stride + offs_d[None, :] * k_head_dim_stride
k = tl.load(K + off_k, mask=offs_n_new[:, None] < current_batch_end_index, other=0.0)
att_value = tl.sum(q[None, :] * k, 1)
att_value *= sm_scale
off_o = current_head * attn_head_stride + (current_batch_in_all_start_index + offs_n) * attn_batch_stride
tl.store(attn_out + off_o, att_value, mask=offs_n_new < current_batch_end_index)
return
@triton.jit
def _token_attn_1_alibi_kernel(Q, K, sm_scale, alibi, kv_cache_loc, kv_cache_start_loc, kv_cache_seqlen,
max_kv_cache_len, attn_out, kv_cache_loc_b_stride, kv_cache_loc_s_stride,
q_batch_stride, q_head_stride, q_head_dim_stride, k_batch_stride, k_head_stride,
k_head_dim_stride, attn_head_stride, attn_batch_stride, HEAD_DIM: tl.constexpr,
BLOCK_N: tl.constexpr):
current_batch = tl.program_id(0)
current_head = tl.program_id(1)
start_n = tl.program_id(2)
offs_d = tl.arange(0, HEAD_DIM)
current_batch_seq_len = tl.load(kv_cache_seqlen + current_batch)
current_batch_in_all_start_index = tl.load(kv_cache_start_loc + current_batch)
current_batch_start_index = max_kv_cache_len - current_batch_seq_len
current_batch_end_index = max_kv_cache_len
off_q = current_batch * q_batch_stride + current_head * q_head_stride + offs_d * q_head_dim_stride
offs_n = start_n * BLOCK_N + tl.arange(0, BLOCK_N)
block_stard_index = start_n * BLOCK_N
block_mask = tl.where(block_stard_index < current_batch_seq_len, 1, 0)
for start_mark in range(0, block_mask, 1):
alibi_m = tl.load(alibi + current_head)
q = tl.load(Q + off_q + start_mark)
offs_n_new = current_batch_start_index + offs_n
k_loc = tl.load(kv_cache_loc + kv_cache_loc_b_stride * current_batch + kv_cache_loc_s_stride * offs_n_new,
mask=offs_n_new < current_batch_end_index,
other=0)
off_k = k_loc[:, None] * k_batch_stride + current_head * k_head_stride + offs_d[None, :] * k_head_dim_stride
k = tl.load(K + off_k, mask=offs_n_new[:, None] < current_batch_end_index, other=0.0)
att_value = tl.sum(q[None, :] * k, 1)
att_value *= sm_scale
att_value -= alibi_m * (current_batch_seq_len - 1 - offs_n)
off_o = current_head * attn_head_stride + (current_batch_in_all_start_index + offs_n) * attn_batch_stride
tl.store(attn_out + off_o, att_value, mask=offs_n_new < current_batch_end_index)
return
@torch.no_grad()
def token_attn_fwd_1(q,
k,
attn_out,
kv_cache_loc,
kv_cache_start_loc,
kv_cache_seqlen,
max_kv_cache_len,
alibi=None):
BLOCK = 32
# shape constraints
q_head_dim, k_head_dim = q.shape[-1], k.shape[-1]
assert q_head_dim == k_head_dim
assert k_head_dim in {16, 32, 64, 128}
sm_scale = 1.0 / (k_head_dim**0.5)
batch, head_num = kv_cache_loc.shape[0], q.shape[1]
grid = (batch, head_num, triton.cdiv(max_kv_cache_len, BLOCK))
num_warps = 4 if k_head_dim <= 64 else 8
num_warps = 2
if alibi is not None:
_token_attn_1_alibi_kernel[grid](
q,
k,
sm_scale,
alibi,
kv_cache_loc,
kv_cache_start_loc,
kv_cache_seqlen,
max_kv_cache_len,
attn_out,
kv_cache_loc.stride(0),
kv_cache_loc.stride(1),
q.stride(0),
q.stride(1),
q.stride(2),
k.stride(0),
k.stride(1),
k.stride(2),
attn_out.stride(0),
attn_out.stride(1),
HEAD_DIM=k_head_dim,
BLOCK_N=BLOCK,
num_warps=num_warps,
num_stages=1,
)
else:
_token_attn_1_kernel[grid](
q,
k,
sm_scale,
kv_cache_loc,
kv_cache_start_loc,
kv_cache_seqlen,
max_kv_cache_len,
attn_out,
kv_cache_loc.stride(0),
kv_cache_loc.stride(1),
q.stride(0),
q.stride(1),
q.stride(2),
k.stride(0),
k.stride(1),
k.stride(2),
attn_out.stride(0),
attn_out.stride(1),
HEAD_DIM=k_head_dim,
BLOCK_N=BLOCK,
num_warps=num_warps,
num_stages=1,
)
return
@triton.jit
def _token_attn_softmax_fwd(softmax_logics, kv_cache_start_loc, kv_cache_seqlen, softmax_prob_out,
logics_head_dim_stride, logics_batch_stride, prob_head_dim_stride, prob_batch_stride,
BLOCK_SIZE: tl.constexpr):
current_batch = tl.program_id(0)
current_head = tl.program_id(1)
col_offsets = tl.arange(0, BLOCK_SIZE)
current_batch_seq_len = tl.load(kv_cache_seqlen + current_batch)
current_batch_in_all_start_index = tl.load(kv_cache_start_loc + current_batch)
row = tl.load(softmax_logics + current_head * logics_head_dim_stride +
(current_batch_in_all_start_index + col_offsets) * logics_batch_stride,
mask=col_offsets < current_batch_seq_len,
other=-float('inf')).to(tl.float32)
row_minus_max = row - tl.max(row, axis=0)
numerator = tl.exp(row_minus_max)
denominator = tl.sum(numerator, axis=0)
softmax_output = numerator / denominator
tl.store(softmax_prob_out + current_head * prob_head_dim_stride +
(current_batch_in_all_start_index + col_offsets) * prob_batch_stride,
softmax_output,
mask=col_offsets < current_batch_seq_len)
return
@torch.no_grad()
def token_attn_softmax_fwd(softmax_logics, kv_cache_start_loc, kv_cache_seqlen, softmax_prob_out, max_kv_cache_len):
BLOCK_SIZE = triton.next_power_of_2(max_kv_cache_len)
batch, head_num = kv_cache_start_loc.shape[0], softmax_logics.shape[0]
num_warps = 4
if BLOCK_SIZE >= 2048:
num_warps = 8
if BLOCK_SIZE >= 4096:
num_warps = 16
_token_attn_softmax_fwd[(batch, head_num)](
softmax_logics,
kv_cache_start_loc,
kv_cache_seqlen,
softmax_prob_out,
softmax_logics.stride(0),
softmax_logics.stride(1),
softmax_prob_out.stride(0),
softmax_prob_out.stride(1),
num_warps=num_warps,
BLOCK_SIZE=BLOCK_SIZE,
)
return
@triton.jit
def _token_attn_2_kernel(Prob, V, attn_out, kv_cache_loc, kv_cache_start_loc, kv_cache_seqlen, max_kv_cache_len,
kv_cache_loc_b_stride, kv_cache_loc_s_stride, prob_head_dim_stride, prob_batch_stride,
v_batch_stride, v_head_stride, v_head_dim_stride, attn_out_batch_stride,
attn_out_head_stride, attn_out_head_dim_stride, HEAD_DIM: tl.constexpr,
BLOCK_N: tl.constexpr):
current_batch = tl.program_id(0)
current_head = tl.program_id(1)
offs_n = tl.arange(0, BLOCK_N)
offs_d = tl.arange(0, HEAD_DIM)
current_batch_seq_len = tl.load(kv_cache_seqlen + current_batch)
current_batch_start_index = max_kv_cache_len - current_batch_seq_len
current_batch_end_index = current_batch_seq_len
current_batch_in_all_start_index = tl.load(kv_cache_start_loc + current_batch)
v_loc_off = current_batch * kv_cache_loc_b_stride + (current_batch_start_index + offs_n) * kv_cache_loc_s_stride
p_offs = current_head * prob_head_dim_stride + (current_batch_in_all_start_index + offs_n) * prob_batch_stride
v_offs = current_head * v_head_stride + offs_d[None, :] * v_head_dim_stride
acc = tl.zeros([HEAD_DIM], dtype=tl.float32)
for start_n in range(0, current_batch_seq_len, BLOCK_N):
start_n = tl.multiple_of(start_n, BLOCK_N)
p_value = tl.load(Prob + p_offs + start_n * kv_cache_loc_s_stride,
mask=(start_n + offs_n) < current_batch_seq_len,
other=0.0)
v_loc = tl.load(kv_cache_loc + v_loc_off + start_n * kv_cache_loc_s_stride,
mask=(start_n + offs_n) < current_batch_seq_len,
other=0.0)
v_value = tl.load(V + v_offs + v_loc[:, None] * v_batch_stride,
mask=(start_n + offs_n[:, None]) < current_batch_seq_len,
other=0.0)
acc += tl.sum(p_value[:, None] * v_value, 0)
acc = acc.to(tl.float16)
off_o = current_batch * attn_out_batch_stride + current_head * attn_out_head_stride + offs_d * attn_out_head_dim_stride
out_ptrs = attn_out + off_o
tl.store(out_ptrs, acc)
return
@torch.no_grad()
def token_attn_fwd_2(prob, v, attn_out, kv_cache_loc, kv_cache_start_loc, kv_cache_seqlen, max_kv_cache_len):
if triton.__version__ >= "2.1.0":
BLOCK = 128
else:
BLOCK = 64
batch, head = kv_cache_loc.shape[0], v.shape[1]
grid = (batch, head)
num_warps = 4
dim = v.shape[-1]
_token_attn_2_kernel[grid](
prob,
v,
attn_out,
kv_cache_loc,
kv_cache_start_loc,
kv_cache_seqlen,
max_kv_cache_len,
kv_cache_loc.stride(0),
kv_cache_loc.stride(1),
prob.stride(0),
prob.stride(1),
v.stride(0),
v.stride(1),
v.stride(2),
attn_out.stride(0),
attn_out.stride(1),
attn_out.stride(2),
HEAD_DIM=dim,
BLOCK_N=BLOCK,
num_warps=num_warps,
num_stages=1,
)
return
@torch.no_grad()
def token_attention_fwd(q,
k,
v,
attn_out,
kv_cache_loc,
kv_cache_start_loc,
kv_cache_seq_len,
max_len_in_batch,
alibi=None):
head_num = k.shape[1]
batch_size = kv_cache_seq_len.shape[0]
calcu_shape1 = (batch_size, head_num, k.shape[2])
total_token_num = k.shape[0]
att_m_tensor = torch.empty((head_num, total_token_num), dtype=q.dtype, device="cuda")
token_attn_fwd_1(q.view(calcu_shape1),
k,
att_m_tensor,
kv_cache_loc,
kv_cache_start_loc,
kv_cache_seq_len,
max_len_in_batch,
alibi=alibi)
prob = torch.empty_like(att_m_tensor)
token_attn_softmax_fwd(att_m_tensor, kv_cache_start_loc, kv_cache_seq_len, prob, max_len_in_batch)
att_m_tensor = None
token_attn_fwd_2(prob, v, attn_out.view(calcu_shape1), kv_cache_loc, kv_cache_start_loc, kv_cache_seq_len,
max_len_in_batch)
prob = None
return