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FastDeploy/test/layers/test_attention.py
2025-06-29 23:29:37 +00:00

340 lines
14 KiB
Python

# Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Adapt from
# https://github.com/sgl-project/sglang/blob/main/python/sglang/test/attention/test_flashattn_backend.py
import unittest
import paddle
from fastdeploy.model_executor.layers.attention import (
Attention, PaddleNativeAttnBackend)
from fastdeploy.worker.forward_meta import (ForwardMeta, ForwardMode,
MHATokenToKVPool)
class MockModelRunner:
def __init__(
self,
page_size=1,
num_heads=2,
head_dim=8,
):
self.device = "cuda"
self.dtype = paddle.float16
# Max batch size for the test.
max_batch_size = 160
# Total tokens(prefix + extend + decode) in the test should not exceed this length.
max_context_len = 2048
self.model_config = type(
"ModelConfig",
(),
{
"context_len": max_context_len,
},
)
self.sliding_window_size = None
self.device = self.device
# Create a large enough req_to_token_pool to fit the test usage.
self.req_to_token_pool = type(
"TokenPool",
(),
{
# A typical max_bs * max_context_len for cuda graph decode
"size":
max_batch_size,
# Add req_to_token attribute
"req_to_token":
paddle.zeros([max_batch_size, max_context_len],
dtype=paddle.int32),
},
)
self.page_size = page_size
max_total_num_tokens = max_batch_size * max_context_len
self.token_to_kv_pool = MHATokenToKVPool(
size=max_total_num_tokens,
page_size=page_size,
dtype=self.dtype,
head_num=num_heads,
head_dim=head_dim,
layer_num=1, # only consider layer=1 for unit test
device=self.device)
class TestNativePaddleAttentionBackend(unittest.TestCase):
def setUp(self):
# Test parameters
self.batch_size = 2
self.seq_len = 256
self.num_heads = 2
self.head_dim = 128
self.device = "gpu"
self.dtype = paddle.float16
def _init_model_runner(self, page_size=1):
self.model_runner = MockModelRunner(
page_size=page_size,
num_heads=self.num_heads,
head_dim=self.head_dim,
)
self.backend = PaddleNativeAttnBackend(self.model_runner)
self.ref_backend = PaddleNativeAttnBackend(self.model_runner)
self.model_runner.model_config.num_attention_heads = self.num_heads
def _mock_write_to_req_to_token_pool(self, batch_size, seq_len, page_size):
# if page_size > 1, the token pool stores the index to the page.
# so we need to multiply the index by page_size.
self.req_to_token = (
paddle.arange(0, batch_size, dtype=paddle.int32)[:, None] * seq_len
+ paddle.arange(0, seq_len, dtype=paddle.int32)[None, :] +
page_size)
self.model_runner.req_to_token_pool.req_to_token[:batch_size, :
seq_len] = (
self.req_to_token)
def _create_attention_layer(self):
"""Create attention layer for testing."""
return Attention(
num_heads=self.num_heads,
head_dim=self.head_dim,
num_kv_heads=self.num_heads,
layer_id=0,
)
def _create_qkv_tensors(self, tokens_len):
"""Create q, k, v tensors for testing."""
shape = (tokens_len, self.num_heads, self.head_dim)
return (
paddle.randn(shape, dtype=self.dtype),
paddle.randn(shape, dtype=self.dtype),
paddle.randn(shape, dtype=self.dtype),
)
def _run_reference_forward(self, mode, q, k, v, layer, forward_batch,
expected_shape):
"""Run reference forward pass using native backend."""
if mode == ForwardMode.EXTEND:
output = self.ref_backend.forward_extend(q, k, v, layer,
forward_batch)
else: # ForwardMode.DECODE
output = self.ref_backend.forward_decode(q, k, v, layer,
forward_batch)
return output.view(expected_shape)
def _verify_output(self, output, expected_shape, output_ref=None):
"""Verify output tensor shape, dtype, and values."""
self.assertEqual(
output.shape,
expected_shape,
f"Expected shape {expected_shape}, got {output.shape}",
)
self.assertEqual(output.dtype, self.dtype)
self.assertEqual(
paddle.isnan(output).sum().item(), 0, "Output contains NaN values")
if output_ref is not None:
if not paddle.allclose(output, output_ref, atol=1e-1, rtol=0.0):
# Check where the values differ beyond the given tolerances
diff_mask = ~paddle.isclose(
output, output_ref, atol=1e-1, rtol=0.0)
# Find the first index where the difference occurs
if diff_mask.any():
first_mismatch_idx = diff_mask.nonzero()[0]
print("First mismatch at index:",
tuple(first_mismatch_idx.tolist()))
print("output:",
output[tuple(first_mismatch_idx.tolist())])
print("output_ref:",
output_ref[tuple(first_mismatch_idx.tolist())])
raise AssertionError(
"Attention output is not close to the torch native backend output"
)
def _create_forward_batch(self,
mode,
q_len=None,
prefix_len=0,
page_size=1):
"""Create a forward batch for testing based on mode and lengths."""
self._init_model_runner(page_size=page_size)
# Default to self.seq_len if not specified
q_len = q_len or self.seq_len
if mode == ForwardMode.EXTEND:
total_len = prefix_len + q_len
out_cache_start = prefix_len * self.batch_size
out_cache_end = total_len * self.batch_size
forward_batch = ForwardMeta(
batch_size=self.batch_size,
input_ids=paddle.randint(0, 100, (self.batch_size, q_len)),
out_cache_loc=paddle.arange(out_cache_start, out_cache_end),
seq_lens_sum=self.batch_size * total_len, # need to be real
forward_mode=mode,
req_pool_indices=paddle.arange(self.batch_size),
seq_lens=paddle.to_tensor([total_len] * self.batch_size),
extend_prefix_lens=paddle.to_tensor([prefix_len] *
self.batch_size),
extend_seq_lens=paddle.to_tensor([q_len] * self.batch_size),
seq_lens_cpu=paddle.to_tensor([total_len] * self.batch_size,
place="cpu"),
extend_prefix_lens_cpu=paddle.to_tensor([prefix_len] *
self.batch_size,
place="cpu"),
extend_seq_lens_cpu=paddle.to_tensor([q_len] * self.batch_size,
place="cpu"),
attn_backend=self.backend,
)
else: # ForwardMode.DECODE
decode_len = q_len # Assuming 1 for decode testing
total_len = self.seq_len + decode_len
if mode == ForwardMode.DECODE and page_size > 1:
# Get next page_size multiple of self.seq_len
out_cache_start = (self.batch_size * self.seq_len // page_size
+ 1) * page_size
# out_cache_end is the start of the next block
out_cache_end = out_cache_start + decode_len * page_size
else:
out_cache_start = self.batch_size * self.seq_len
out_cache_end = self.batch_size * total_len
forward_batch = ForwardMeta(
batch_size=self.batch_size,
input_ids=paddle.randint(0, 100,
(self.batch_size, decode_len)),
out_cache_loc=paddle.to_tensor(
[out_cache_start, out_cache_end]),
seq_lens_sum=self.batch_size * total_len,
forward_mode=mode,
req_pool_indices=paddle.arange(self.batch_size),
seq_lens=paddle.to_tensor([total_len] * self.batch_size),
seq_lens_cpu=paddle.to_tensor([total_len] * self.batch_size,
place="cpu"),
attn_backend=self.backend,
)
# Add token pool
forward_batch.req_to_token_pool = self.model_runner.req_to_token_pool
# Write current batch's req_to_token to req_to_token_pool
self._mock_write_to_req_to_token_pool(self.batch_size, total_len,
page_size)
# Add kv pool for this forward batch
forward_batch.token_to_kv_pool = self.model_runner.token_to_kv_pool
return forward_batch
def _setup_kv_cache(self, forward_batch, layer, cache_len):
# Create constant values for the prefix cache for easy debugging
cache_k = paddle.ones(
[self.batch_size * cache_len, self.num_heads, self.head_dim],
dtype=self.dtype,
)
cache_v = (paddle.ones(
[self.batch_size * cache_len, self.num_heads, self.head_dim],
dtype=self.dtype,
) * 2)
# Set the prefix KV cache
forward_batch.token_to_kv_pool.set_kv_buffer(
layer,
paddle.arange(self.batch_size * cache_len),
cache_k,
cache_v,
layer.k_scale,
layer.v_scale,
)
def _run_attention_test(self, mode, q_len, prefix_len=0, page_size=1):
"""
Run an attention test with the specified parameters.
Args:
mode: ForwardMode.EXTEND or ForwardMode.DECODE
q_len: Length of the query sequence. For decode mode, q_len is 1.
prefix_len: Length of the prefix sequence for extend mode
page_size: Page size for the KV cache
"""
layer = self._create_attention_layer()
# Create forward batch and set up
forward_batch = self._create_forward_batch(mode, q_len, prefix_len,
page_size)
# Create QKV tensors for the input
q, k, v = self._create_qkv_tensors(self.batch_size * q_len)
# KV cache for prefixed extend is prefix_len
# KV cache for decode is same as seq_len
# No KV cache for extend without prefix
if mode == ForwardMode.EXTEND:
if prefix_len > 0:
self._setup_kv_cache(forward_batch, layer, prefix_len)
else:
self._setup_kv_cache(forward_batch, layer, self.seq_len)
self.backend.init_attention_metadata(forward_batch)
if mode == ForwardMode.EXTEND:
expected_shape = [
self.batch_size * q_len,
self.num_heads,
self.head_dim,
]
output = self.backend.forward_extend(q, k, v, layer, forward_batch)
else:
expected_shape = [self.batch_size, self.num_heads * self.head_dim]
output = self.backend.forward_decode(q, k, v, layer, forward_batch)
output_ref = self._run_reference_forward(mode, q, k, v, layer,
forward_batch, expected_shape)
self._verify_output(output, expected_shape, output_ref)
return output
def test_forward_extend(self):
"""Test the standard extend operation."""
self._run_attention_test(ForwardMode.EXTEND, q_len=self.seq_len)
def test_forward_decode(self):
"""Test the decode operation with cached tokens."""
self._run_attention_test(ForwardMode.DECODE, q_len=1)
def test_forward_extend_with_prefix(self):
"""Test extending from cached prefix tokens."""
prefix_len = self.seq_len // 2
extend_len = self.seq_len - prefix_len
self._run_attention_test(ForwardMode.EXTEND,
q_len=extend_len,
prefix_len=prefix_len)
def test_forward_extend_with_page_size_greater_than_1(self):
"""Test extending from cached prefix tokens with page size greater than 1."""
self._run_attention_test(ForwardMode.EXTEND,
q_len=self.seq_len,
page_size=64)
def test_forward_decode_with_page_size_greater_than_1(self):
"""Test decode operation with page size greater than 1."""
self._run_attention_test(ForwardMode.DECODE, q_len=1, page_size=64)
if __name__ == "__main__":
unittest.main()