Files
xc-llm-ascend/tests/ut/attention/test_attention_mask.py
ApsarasX 643e6f5486 [Bugfix] Fix accuracy problem caused by mask pollution (#1678)
### What this PR does / why we need it?
If a small batch of short requests is sent first, forming a chunk with a
length <128, it will corrupt the `attn_mask_cache`, causing subsequent
requests that do not form a chunk to have accuracy issues.

The root cause of this problem is the use of in-place multiplication.
Modifying it to use out-of-place multiplication will resolve the
accuracy problem.


### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
Yes.

- vLLM version: v0.9.2
- vLLM main:
ad6c2e1a0b

---------

Signed-off-by: ApsarasX <apsarax@outlook.com>
2025-07-10 14:06:49 +08:00

157 lines
7.5 KiB
Python

#
# Copyright (c) 2025 Huawei Technologies Co., Ltd. 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.
import torch
from tests.ut.base import TestBase
from vllm_ascend.attention.attention_mask import AttentionMaskBuilder
class TestAttentionMaskBuilder(TestBase):
def test_init_attention_mask_builder(self):
# generate attention_mask_builder with float16
attention_mask_builder = AttentionMaskBuilder(max_seq_len=1024,
dtype=torch.float16)
self.assertEqual(attention_mask_builder._seq_len_cached, 1024)
self.assertEqual(attention_mask_builder.attn_mask_cache.dtype,
torch.float16)
self.assertEqual(attention_mask_builder.splitfuse_mask_value, -10000)
self.assertEqual(attention_mask_builder.attn_mask_cache.shape,
(1024, 1024))
self.assertEqual(attention_mask_builder.attn_mask_cache[0][-1],
torch.tensor(float("-inf"), dtype=torch.float16))
# generate attention_mask_builder with int8
attention_mask_builder = AttentionMaskBuilder(max_seq_len=512,
dtype=torch.int8)
self.assertEqual(attention_mask_builder._seq_len_cached, 512)
self.assertEqual(attention_mask_builder.attn_mask_cache.dtype,
torch.int8)
self.assertEqual(attention_mask_builder.splitfuse_mask_value, -10000)
self.assertEqual(attention_mask_builder.attn_mask_cache.shape,
(512, 512))
self.assertEqual(attention_mask_builder.attn_mask_cache[0][-1],
torch.tensor(1, dtype=torch.int8))
def test_get_attn_mask(self):
# if the len is less than max_seq_len, the attn_mask_cache will not be updated
attention_mask_builder = AttentionMaskBuilder(max_seq_len=1024,
dtype=torch.float16)
attn_mask = attention_mask_builder.get_attn_mask(
max_seq_len=512, dtype=torch.float16, device=torch.device("cpu"))
self.assertEqual(attn_mask.shape, (512, 512))
self.assertEqual(attn_mask[0][-1],
torch.tensor(float("-inf"), dtype=torch.float16))
self.assertEqual(attention_mask_builder._seq_len_cached, 1024)
self.assertEqual(attention_mask_builder.attn_mask_cache.shape,
(1024, 1024))
self.assertEqual(attention_mask_builder.attn_mask_cache[0][-1],
torch.tensor(float("-inf"), dtype=torch.float16))
# if the len is greater than max_seq_len, the attn_mask_cache will be updated
attn_mask = attention_mask_builder.get_attn_mask(
max_seq_len=2048, dtype=torch.float16, device=torch.device("cpu"))
self.assertEqual(attn_mask.shape, (2048, 2048))
self.assertEqual(attn_mask[0][-1],
torch.tensor(float("-inf"), dtype=torch.float16))
self.assertEqual(attention_mask_builder._seq_len_cached, 2048)
self.assertEqual(attention_mask_builder.attn_mask_cache.shape,
(2048, 2048))
self.assertEqual(attention_mask_builder.attn_mask_cache[0][-1],
torch.tensor(float("-inf"), dtype=torch.float16))
def test_get_splitfuse_attn_mask(self):
attention_mask_builder = AttentionMaskBuilder(max_seq_len=1024,
dtype=torch.float16)
attn_mask = attention_mask_builder.get_splitfuse_attn_mask(
seq_lens=[512],
query_lens=[512],
position=torch.tensor([0]),
dtype=torch.float16,
device=torch.device("cpu"),
)
self.assertEqual(attn_mask.shape, (1, 512))
self.assertEqual(attention_mask_builder._seq_len_cached, 1024)
attn_mask = attention_mask_builder.get_splitfuse_attn_mask(
seq_lens=[2048],
query_lens=[1024],
position=torch.tensor([0]),
dtype=torch.float16,
device=torch.device("cpu"),
)
self.assertEqual(attn_mask.shape, (1024, 2048))
attention_mask_builder = AttentionMaskBuilder(max_seq_len=1024,
dtype=torch.int8)
attn_mask = attention_mask_builder.get_splitfuse_attn_mask(
seq_lens=[512],
query_lens=[512],
position=torch.tensor([0]),
dtype=torch.int8,
device=torch.device("cpu"),
)
self.assertEqual(attn_mask.shape, (1, 512))
def test_use_multiple_masks(self):
max_seq_lens = [128, 512, 1024]
dtypes = [torch.float16, torch.bfloat16, torch.int8]
for max_seq_len, dtype in zip(max_seq_lens, dtypes):
with self.subTest(max_seq_len=max_seq_len, dtype=dtype):
self._test_use_multiple_masks(max_seq_len, dtype)
def _test_use_multiple_masks(self, max_seq_len, dtype):
expected_mask_value = torch.finfo(
torch.float32).min if dtype == torch.float16 else 1
if dtype == torch.float16:
expected_splitfuse_mask_value = expected_mask_value
elif dtype == torch.bfloat16:
expected_splitfuse_mask_value = -10000
else:
assert dtype == torch.int8, "Unsupported dtype for attention mask"
expected_splitfuse_mask_value = -16
attention_mask_builder = AttentionMaskBuilder(max_seq_len=max_seq_len,
dtype=dtype)
splitfuse_attn_mask = attention_mask_builder.get_splitfuse_attn_mask(
seq_lens=[max_seq_len],
query_lens=[max_seq_len],
position=torch.tensor([0]),
dtype=dtype,
device=torch.device("cpu"),
)
self.assertEqual(splitfuse_attn_mask.shape, (1, max_seq_len))
self.assertEqual(
splitfuse_attn_mask[0][-1],
torch.tensor(expected_splitfuse_mask_value, dtype=dtype))
self.assertEqual(attention_mask_builder._seq_len_cached, max_seq_len)
self.assertEqual(attention_mask_builder.attn_mask_cache.shape,
(max_seq_len, max_seq_len))
self.assertEqual(attention_mask_builder.attn_mask_cache[0][-1],
torch.tensor(expected_mask_value, dtype=dtype))
attn_mask = attention_mask_builder.get_attn_mask(
max_seq_len=max_seq_len, dtype=dtype, device=torch.device("cpu"))
self.assertEqual(attn_mask.shape, (max_seq_len, max_seq_len))
self.assertEqual(attn_mask[0][-1],
torch.tensor(expected_mask_value, dtype=dtype))
self.assertEqual(attention_mask_builder._seq_len_cached, max_seq_len)
self.assertEqual(attention_mask_builder.attn_mask_cache.shape,
(max_seq_len, max_seq_len))
self.assertEqual(attention_mask_builder.attn_mask_cache[0][-1],
torch.tensor(expected_mask_value, dtype=dtype))