Unverified Commit d9a20fd2 authored by Qiaolin Yu's avatar Qiaolin Yu Committed by GitHub
Browse files

Use trtllm_mla decode kernel for draft extend in speculative decoding (#11664)

parent b113c72e
......@@ -10,6 +10,7 @@ from typing import TYPE_CHECKING, Optional, Union
import torch
import triton
import triton.language as tl
from sglang.srt.layers.attention.flashinfer_mla_backend import (
FlashInferMLAAttnBackend,
......@@ -48,6 +49,151 @@ DEFAULT_WORKSPACE_SIZE_MB = 128 # Memory workspace size in MB
# compute the LCM with other padding constraints.
TRTLLM_BLOCK_CONSTRAINT = 128
@triton.jit
def pad_draft_extend_query_kernel(
q_ptr, # Input query tensor [total_seq_len, num_heads, head_dim]
padded_q_ptr, # Output padded query tensor [batch_size, max_seq_len, num_heads, head_dim]
seq_lens_q_ptr, # Sequence lengths for each sequence [batch_size]
cumsum_ptr, # Cumulative sum of accept lengths [batch_size + 1]
batch_size,
max_seq_len,
num_heads,
head_dim,
BLOCK_SIZE: tl.constexpr,
):
"""Triton kernel for padding draft extended query tensor with parallelized head and dim processing."""
# Use 3D program IDs: (batch_seq, head_block, dim_block)
batch_seq_pid = tl.program_id(0)
head_pid = tl.program_id(1)
dim_pid = tl.program_id(2)
batch_id = batch_seq_pid // max_seq_len
seq_pos = batch_seq_pid % max_seq_len
if batch_id >= batch_size:
return
# Load accept length for this batch
seq_len = tl.load(seq_lens_q_ptr + batch_id)
if seq_pos >= seq_len:
return
# Load cumulative sum to get start position in input tensor
input_start = tl.load(cumsum_ptr + batch_id)
input_pos = input_start + seq_pos
# Calculate head and dim block ranges
head_start = head_pid * BLOCK_SIZE
head_end = tl.minimum(head_start + BLOCK_SIZE, num_heads)
head_mask = tl.arange(0, BLOCK_SIZE) < (head_end - head_start)
dim_start = dim_pid * BLOCK_SIZE
dim_end = tl.minimum(dim_start + BLOCK_SIZE, head_dim)
dim_mask = tl.arange(0, BLOCK_SIZE) < (dim_end - dim_start)
# Calculate input offset
input_offset = (
input_pos * num_heads * head_dim
+ (head_start + tl.arange(0, BLOCK_SIZE))[:, None] * head_dim
+ (dim_start + tl.arange(0, BLOCK_SIZE))[None, :]
)
# Load data
data = tl.load(
q_ptr + input_offset,
mask=head_mask[:, None] & dim_mask[None, :],
other=0.0,
)
# Calculate output offset
output_offset = (
batch_id * max_seq_len * num_heads * head_dim
+ seq_pos * num_heads * head_dim
+ (head_start + tl.arange(0, BLOCK_SIZE))[:, None] * head_dim
+ (dim_start + tl.arange(0, BLOCK_SIZE))[None, :]
)
# Store data
tl.store(
padded_q_ptr + output_offset,
data,
mask=head_mask[:, None] & dim_mask[None, :],
)
@triton.jit
def unpad_draft_extend_output_kernel(
raw_out_ptr, # Input raw output tensor (batch_size, token_per_batch, tp_q_head_num, v_head_dim)
output_ptr, # Output tensor (-1, tp_q_head_num, v_head_dim)
accept_length_ptr, # Accept lengths for each sequence [batch_size]
cumsum_ptr, # Cumulative sum of accept lengths [batch_size + 1]
batch_size,
token_per_batch,
tp_q_head_num,
v_head_dim,
BLOCK_SIZE: tl.constexpr,
):
"""Triton kernel for unpadding draft extended output tensor with parallelized head and dim processing."""
batch_seq_pid = tl.program_id(0)
head_pid = tl.program_id(1)
dim_pid = tl.program_id(2)
batch_id = batch_seq_pid // token_per_batch
seq_pos = batch_seq_pid % token_per_batch
if batch_id >= batch_size:
return
# Load accept length for this batch
accept_len = tl.load(accept_length_ptr + batch_id)
if seq_pos >= accept_len:
return
# Load cumulative sum to get start position in output tensor
output_start = tl.load(cumsum_ptr + batch_id)
output_pos = output_start + seq_pos
# Calculate head and dim block ranges
head_start = head_pid * BLOCK_SIZE
head_end = tl.minimum(head_start + BLOCK_SIZE, tp_q_head_num)
head_mask = tl.arange(0, BLOCK_SIZE) < (head_end - head_start)
dim_start = dim_pid * BLOCK_SIZE
dim_end = tl.minimum(dim_start + BLOCK_SIZE, v_head_dim)
dim_mask = tl.arange(0, BLOCK_SIZE) < (dim_end - dim_start)
# Calculate input offset: (batch_id, seq_pos, head_id, dim_id)
input_offset = (
batch_id * token_per_batch * tp_q_head_num * v_head_dim
+ seq_pos * tp_q_head_num * v_head_dim
+ (head_start + tl.arange(0, BLOCK_SIZE))[:, None] * v_head_dim
+ (dim_start + tl.arange(0, BLOCK_SIZE))[None, :]
)
# Load data
data = tl.load(
raw_out_ptr + input_offset,
mask=head_mask[:, None] & dim_mask[None, :],
other=0.0,
)
output_offset = (
output_pos * tp_q_head_num * v_head_dim
+ (head_start + tl.arange(0, BLOCK_SIZE))[:, None] * v_head_dim
+ (dim_start + tl.arange(0, BLOCK_SIZE))[None, :]
)
# Store data
tl.store(
output_ptr + output_offset,
data,
mask=head_mask[:, None] & dim_mask[None, :],
)
global_zero_init_workspace_buffer = None
......@@ -65,7 +211,11 @@ class TRTLLMMLADecodeMetadata:
"""Metadata for TRTLLM MLA decode operations."""
block_kv_indices: Optional[torch.Tensor] = None
max_seq_len: Optional[int] = None
max_seq_len_k: Optional[int] = None
max_seq_len_q: Optional[int] = None
sum_seq_lens_q: Optional[int] = None
cu_seqlens_q: Optional[torch.Tensor] = None
seq_lens_q: Optional[torch.Tensor] = None
class TRTLLMMLABackend(FlashInferMLAAttnBackend):
......@@ -120,6 +270,8 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
# CUDA graph state
self.decode_cuda_graph_metadata = {}
self.decode_cuda_graph_kv_indices = None
self.padded_q_buffer = None
self.unpad_output_buffer = None
self.forward_prefill_metadata: Optional[TRTLLMMLAPrefillMetadata] = None
self.forward_decode_metadata: Union[TRTLLMMLADecodeMetadata, None] = None
......@@ -203,6 +355,21 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
self.decode_cuda_graph_kv_indices = torch.full(
(max_bs, max_blocks_per_seq), -1, dtype=torch.int32, device=self.device
)
num_tokens_per_bs = max_num_tokens // max_bs
# Buffer for padded query: (max_bs, max_draft_tokens, num_q_heads, v_head_dim)
self.padded_q_buffer = torch.zeros(
(max_bs, num_tokens_per_bs, self.num_q_heads, self.kv_cache_dim),
dtype=self.data_type,
device=self.device,
)
# Buffer for unpadded output: (max_num_tokens, num_q_heads, v_head_dim)
self.unpad_output_buffer = torch.zeros(
(max_num_tokens, self.num_q_heads, 512),
dtype=self.data_type,
device=self.device,
)
super().init_cuda_graph_state(max_bs, max_num_tokens, kv_indices_buf)
......@@ -219,7 +386,11 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
"""Initialize metadata for CUDA graph capture."""
# Delegate to parent for non-decode modes.
if not forward_mode.is_decode_or_idle() and not forward_mode.is_target_verify():
if (
not forward_mode.is_decode_or_idle()
and not forward_mode.is_target_verify()
and not forward_mode.is_draft_extend()
):
return super().init_forward_metadata_capture_cuda_graph(
bs,
num_tokens,
......@@ -259,6 +430,20 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
block_kv_indices,
max_seq_len_val,
)
if forward_mode.is_draft_extend():
num_tokens_per_bs = num_tokens // bs
metadata.max_seq_len_q = num_tokens_per_bs + 1
metadata.sum_seq_lens_q = num_tokens_per_bs * bs
metadata.cu_seqlens_q = torch.arange(
0,
bs * num_tokens_per_bs + 1,
num_tokens_per_bs,
dtype=torch.int32,
device=seq_lens.device,
)
metadata.seq_lens_q = torch.full(
(bs,), num_tokens_per_bs, dtype=torch.int32, device=seq_lens.device
)
self.decode_cuda_graph_metadata[bs] = metadata
self.forward_decode_metadata = metadata
......@@ -275,7 +460,11 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
):
"""Replay CUDA graph with new inputs."""
# Delegate to parent for non-decode modes.
if not forward_mode.is_decode_or_idle() and not forward_mode.is_target_verify():
if (
not forward_mode.is_decode_or_idle()
and not forward_mode.is_target_verify()
and not forward_mode.is_draft_extend()
):
return super().init_forward_metadata_replay_cuda_graph(
bs,
req_pool_indices,
......@@ -293,6 +482,19 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
metadata = self.decode_cuda_graph_metadata[bs]
if forward_mode.is_draft_extend():
accept_length = spec_info.accept_length[:bs]
if spec_info.accept_length_cpu:
metadata.max_seq_len_q = max(spec_info.accept_length_cpu[:bs])
metadata.sum_seq_lens_q = sum(spec_info.accept_length_cpu[:bs])
else:
metadata.max_seq_len_q = 1
metadata.sum_seq_lens_q = bs
metadata.cu_seqlens_q[1:].copy_(
torch.cumsum(accept_length, dim=0, dtype=torch.int32)
)
metadata.seq_lens_q.copy_(accept_length)
# Update block indices for new sequences.
create_flashmla_kv_indices_triton[(bs,)](
self.req_to_token,
......@@ -344,6 +546,7 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
elif (
forward_batch.forward_mode.is_decode_or_idle()
or forward_batch.forward_mode.is_target_verify()
or forward_batch.forward_mode.is_draft_extend()
):
bs = forward_batch.batch_size
......@@ -372,6 +575,23 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
self.forward_decode_metadata = TRTLLMMLADecodeMetadata(
block_kv_indices, max_seq_len_val
)
if forward_batch.forward_mode.is_draft_extend():
max_seq = forward_batch.seq_lens_cpu.max().item()
sum_seq_lens_q = sum(forward_batch.extend_seq_lens_cpu)
max_seq_len_q = max(forward_batch.extend_seq_lens_cpu)
cu_seqlens_q = torch.nn.functional.pad(
torch.cumsum(
forward_batch.extend_seq_lens, dim=0, dtype=torch.int32
),
(1, 0),
)
self.forward_decode_metadata.max_seq_len_q = max_seq_len_q
self.forward_decode_metadata.sum_seq_lens_q = sum_seq_lens_q
self.forward_decode_metadata.cu_seqlens_q = cu_seqlens_q
self.forward_decode_metadata.seq_lens_q = forward_batch.extend_seq_lens
forward_batch.decode_trtllm_mla_metadata = self.forward_decode_metadata
else:
return super().init_forward_metadata(forward_batch)
......@@ -457,6 +677,86 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
return q_out, k_nope_out, k_rope_out
def pad_draft_extend_query(
self,
q: torch.Tensor,
padded_q: torch.Tensor,
seq_lens_q: torch.Tensor,
cu_seqlens_q: torch.Tensor,
) -> torch.Tensor:
"""Pad draft extended query using Triton kernel."""
batch_size = cu_seqlens_q.shape[0] - 1
max_seq_len_q = padded_q.shape[1]
num_heads = padded_q.shape[2]
head_dim = padded_q.shape[3]
# Launch Triton kernel with 3D grid for parallelized head and dim processing
BLOCK_SIZE = 64
num_head_blocks = triton.cdiv(num_heads, BLOCK_SIZE)
num_dim_blocks = triton.cdiv(head_dim, BLOCK_SIZE)
grid = (batch_size * max_seq_len_q, num_head_blocks, num_dim_blocks)
pad_draft_extend_query_kernel[grid](
q_ptr=q,
padded_q_ptr=padded_q,
seq_lens_q_ptr=seq_lens_q,
cumsum_ptr=cu_seqlens_q,
batch_size=batch_size,
max_seq_len=max_seq_len_q,
num_heads=num_heads,
head_dim=head_dim,
BLOCK_SIZE=BLOCK_SIZE,
)
return padded_q
def unpad_draft_extend_output(
self,
raw_out: torch.Tensor,
cu_seqlens_q: torch.Tensor,
seq_lens_q: torch.Tensor,
sum_seq_lens_q: int,
) -> torch.Tensor:
"""Unpad draft extended output using Triton kernel."""
# raw_out: (batch_size, token_per_batch, layer.tp_q_head_num, layer.v_head_dim)
batch_size = seq_lens_q.shape[0]
token_per_batch = raw_out.shape[1] # max_seq_len
tp_q_head_num = raw_out.shape[2] # num_heads
v_head_dim = raw_out.shape[3] # head_dim
total_tokens = sum_seq_lens_q
# Check if we're in CUDA graph mode (buffers are pre-allocated)
if self.unpad_output_buffer is not None:
# Use pre-allocated buffer for CUDA graph compatibility
output = self.unpad_output_buffer[:total_tokens, :, :].to(
dtype=raw_out.dtype
)
else:
# Dynamic allocation for non-CUDA graph mode
output = torch.empty(
(total_tokens, tp_q_head_num, v_head_dim),
dtype=raw_out.dtype,
device=raw_out.device,
)
# Launch Triton kernel with 3D grid for parallelized head and dim processing
BLOCK_SIZE = 64
num_head_blocks = triton.cdiv(tp_q_head_num, BLOCK_SIZE)
num_dim_blocks = triton.cdiv(v_head_dim, BLOCK_SIZE)
grid = (batch_size * token_per_batch, num_head_blocks, num_dim_blocks)
unpad_draft_extend_output_kernel[grid](
raw_out_ptr=raw_out,
output_ptr=output,
accept_length_ptr=seq_lens_q,
cumsum_ptr=cu_seqlens_q,
batch_size=batch_size,
token_per_batch=token_per_batch,
tp_q_head_num=tp_q_head_num,
v_head_dim=v_head_dim,
BLOCK_SIZE=BLOCK_SIZE,
)
return output[:total_tokens, :, :]
def forward_decode(
self,
q: torch.Tensor, # q_nope
......@@ -550,7 +850,7 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
qk_rope_head_dim=self.qk_rope_head_dim,
block_tables=metadata.block_kv_indices,
seq_lens=forward_batch.seq_lens.to(torch.int32),
max_seq_len=metadata.max_seq_len,
max_seq_len=metadata.max_seq_len_k,
bmm1_scale=bmm1_scale,
)
......@@ -571,11 +871,6 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
cos_sin_cache: Optional[torch.Tensor] = None,
is_neox: Optional[bool] = False,
) -> torch.Tensor:
if forward_batch.forward_mode.is_draft_extend():
return super().forward_extend(
q, k, v, layer, forward_batch, save_kv_cache, q_rope, k_rope
)
# TODO refactor to avoid code duplication
merge_query = q_rope is not None
if (
......@@ -627,7 +922,10 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
v = v.view(-1, layer.tp_k_head_num, layer.v_head_dim)
if forward_batch.forward_mode.is_target_verify():
if (
forward_batch.forward_mode.is_target_verify()
or forward_batch.forward_mode.is_draft_extend()
):
metadata = (
getattr(forward_batch, "decode_trtllm_mla_metadata", None)
or self.forward_decode_metadata
......@@ -635,7 +933,6 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
# Ensure query has shape [bs, num_draft_tokens, num_q_heads, head_dim]
bs = forward_batch.batch_size
q = q.view(bs, -1, layer.tp_q_head_num, layer.head_dim)
k_cache = forward_batch.token_to_kv_pool.get_key_buffer(layer.layer_id)
kv_cache = k_cache.view(-1, self.page_size, self.kv_cache_dim).unsqueeze(1)
......@@ -646,17 +943,42 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
if getattr(layer, "k_scale_float", None) is not None
else 1.0
)
q = q.to(self.data_type)
bmm1_scale = q_scale * k_scale * layer.scaling
seq_lens = (
forward_batch.seq_lens.to(torch.int32)
+ forward_batch.spec_info.draft_token_num
)
max_seq_len = metadata.max_seq_len + forward_batch.spec_info.draft_token_num
if forward_batch.forward_mode.is_target_verify():
seq_lens = (
forward_batch.seq_lens.to(torch.int32)
+ forward_batch.spec_info.draft_token_num
)
max_seq_len = (
metadata.max_seq_len_k + forward_batch.spec_info.draft_token_num
)
else:
seq_lens = forward_batch.seq_lens.to(torch.int32)
max_seq_len = metadata.max_seq_len_k
# Check if we're in CUDA graph mode (buffers are pre-allocated)
if self.padded_q_buffer is not None:
# Use pre-allocated buffer for CUDA graph compatibility
padded_q = self.padded_q_buffer[
:bs, : metadata.max_seq_len_q, :, :
].to(dtype=q.dtype)
else:
# Dynamic allocation for non-CUDA graph mode
padded_q = torch.zeros(
bs,
metadata.max_seq_len_q,
layer.tp_q_head_num,
layer.head_dim,
dtype=q.dtype,
device=q.device,
)
q = self.pad_draft_extend_query(
q, padded_q, metadata.seq_lens_q, metadata.cu_seqlens_q
)
# TODO may use `mla_rope_quantize_fp8` fusion
q = q.to(self.data_type)
q = q.view(bs, -1, layer.tp_q_head_num, layer.head_dim)
assert kv_cache.dtype == self.data_type
raw_out = flashinfer.decode.trtllm_batch_decode_with_kv_cache_mla(
......@@ -673,6 +995,14 @@ class TRTLLMMLABackend(FlashInferMLAAttnBackend):
)
# Reshape output directly without slicing
if forward_batch.forward_mode.is_draft_extend():
raw_out = self.unpad_draft_extend_output(
raw_out,
metadata.cu_seqlens_q,
metadata.seq_lens_q,
metadata.sum_seq_lens_q,
)
output = raw_out.view(-1, layer.tp_q_head_num * layer.v_head_dim)
return output
......
......@@ -1263,6 +1263,178 @@ class TestTRTLLMMLA(CustomTestCase):
f"Max diff: {(out_trtllm - out_reference).abs().max().item()}",
)
def test_draft_extend_padding_unpadding_kernels(self):
"""Test TRTLLM MLA Triton kernels: pad_draft_extend_query_kernel and unpad_draft_extend_output_kernel."""
# Import the kernels
from sglang.srt.layers.attention.trtllm_mla_backend import (
pad_draft_extend_query_kernel,
unpad_draft_extend_output_kernel,
)
def _create_test_data(
self, batch_size, max_seq_len, num_heads, head_dim, dtype=torch.float32
):
"""Create test data for kernel testing."""
device = torch.device("cuda")
# Create sequence lengths (varying lengths for each batch)
seq_lens = torch.randint(
1, max_seq_len + 1, (batch_size,), device=device, dtype=torch.int32
)
# Create cumulative sequence lengths
cum_seq_lens = torch.zeros(batch_size + 1, device=device, dtype=torch.int32)
cum_seq_lens[1:] = torch.cumsum(seq_lens, dim=0)
# Create input query tensor (flattened format)
total_tokens = cum_seq_lens[-1].item()
q_input = torch.randn(
total_tokens, num_heads, head_dim, device=device, dtype=dtype
)
# Create padded query tensor (batch format)
padded_q = torch.zeros(
batch_size, max_seq_len, num_heads, head_dim, device=device, dtype=dtype
)
return q_input, padded_q, seq_lens, cum_seq_lens
def _create_test_output_data(
self,
batch_size,
token_per_batch,
tp_q_head_num,
v_head_dim,
dtype=torch.float32,
):
"""Create test data for unpad kernel testing."""
device = torch.device("cuda")
# Create accept lengths (varying lengths for each batch)
accept_lengths = torch.randint(
1, token_per_batch + 1, (batch_size,), device=device, dtype=torch.int32
)
# Create cumulative accept lengths
cum_accept_lengths = torch.zeros(
batch_size + 1, device=device, dtype=torch.int32
)
cum_accept_lengths[1:] = torch.cumsum(accept_lengths, dim=0)
# Create raw output tensor (batch format)
raw_out = torch.randn(
batch_size,
token_per_batch,
tp_q_head_num,
v_head_dim,
device=device,
dtype=dtype,
)
# Create output tensor (flattened format)
total_tokens = cum_accept_lengths[-1].item()
output = torch.empty(
total_tokens, tp_q_head_num, v_head_dim, device=device, dtype=dtype
)
return raw_out, output, accept_lengths, cum_accept_lengths
# Test 1: pad_draft_extend_query_kernel basic functionality
with self.subTest(test="pad_kernel_basic"):
batch_size = 4
max_seq_len = 8
num_heads = 16
head_dim = 64
q_input, padded_q, seq_lens, cum_seq_lens = _create_test_data(
self, batch_size, max_seq_len, num_heads, head_dim
)
# Launch kernel
BLOCK_SIZE = 64
grid = (batch_size * max_seq_len,)
pad_draft_extend_query_kernel[grid](
q_ptr=q_input,
padded_q_ptr=padded_q,
seq_lens_q_ptr=seq_lens,
cumsum_ptr=cum_seq_lens,
batch_size=batch_size,
max_seq_len=max_seq_len,
num_heads=num_heads,
head_dim=head_dim,
BLOCK_SIZE=BLOCK_SIZE,
)
# Verify the padding worked correctly
for i in range(batch_size):
seq_len = seq_lens[i].item()
# Check that valid positions are copied correctly
for pos in range(seq_len):
input_start = cum_seq_lens[i].item()
input_pos = input_start + pos
# Compare input and output for valid positions
input_data = q_input[input_pos]
output_data = padded_q[i, pos]
torch.testing.assert_close(
input_data, output_data, rtol=1e-5, atol=1e-6
)
# Check that invalid positions are zero
for pos in range(seq_len, max_seq_len):
output_data = padded_q[i, pos]
self.assertTrue(
torch.allclose(output_data, torch.zeros_like(output_data)),
f"Position {pos} in batch {i} should be zero",
)
# Test 2: unpad_draft_extend_output_kernel basic functionality
with self.subTest(test="unpad_kernel_basic"):
batch_size = 4
token_per_batch = 8
tp_q_head_num = 16
v_head_dim = 64
raw_out, output, accept_lengths, cum_accept_lengths = (
_create_test_output_data(
self, batch_size, token_per_batch, tp_q_head_num, v_head_dim
)
)
# Launch kernel
BLOCK_SIZE = 64
grid = (batch_size * token_per_batch,)
unpad_draft_extend_output_kernel[grid](
raw_out_ptr=raw_out,
output_ptr=output,
accept_length_ptr=accept_lengths,
cumsum_ptr=cum_accept_lengths,
batch_size=batch_size,
token_per_batch=token_per_batch,
tp_q_head_num=tp_q_head_num,
v_head_dim=v_head_dim,
BLOCK_SIZE=BLOCK_SIZE,
)
# Verify the unpadding worked correctly
for i in range(batch_size):
accept_len = accept_lengths[i].item()
output_start = cum_accept_lengths[i].item()
# Check that valid positions are copied correctly
for pos in range(accept_len):
input_data = raw_out[i, pos]
output_data = output[output_start + pos]
torch.testing.assert_close(
input_data, output_data, rtol=1e-5, atol=1e-6
)
if __name__ == "__main__":
unittest.main()
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