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paddlepaddle--paddle/python/paddle/sparse/nn/functional/transformer.py
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2026-07-13 12:40:42 +08:00

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# Copyright (c) 2022 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.
from __future__ import annotations
from typing import TYPE_CHECKING
__all__ = []
from paddle import _C_ops
from paddle.base.framework import in_dynamic_or_pir_mode
if TYPE_CHECKING:
from paddle import Tensor
def attention(
query: Tensor,
key: Tensor,
value: Tensor,
sparse_mask: Tensor,
key_padding_mask: Tensor | None = None,
attn_mask: Tensor | None = None,
name: str | None = None,
) -> Tensor:
r"""
Note:
This API is only used from ``CUDA 11.8`` .
SparseCsrTensor is used to store the intermediate result of Attention matrix
in Transformer module, which can reduce memory usage and improve performance.
``sparse_mask`` express the sparse layout in CSR format.
The calculation equation is:
.. math::
result = softmax(\frac{ Q * K^T }{\sqrt{d}}) * V
where : ``Q``, ``K``, and ``V`` represent the three input parameters of the attention module.
The shape of the three parameters are: `[batch_size, num_heads, seq_len, head_dim]`, and
``d`` represents ``head_dim`` .
Args:
query (DenseTensor): `query` in the Attention module. 4D Tensor with float32 or float64.
key (DenseTensor): `key` in the Attention module. 4D Tensor with float32 or float64.
value (DenseTensor): `value` in the Attention module. 4D Tensor with float32 or float64.
sparse_mask (SparseCsrTensor): The sparse layout in the Attention module. Its dense shape
is `[batch_size*num_heads, seq_len, seq_len]`. `nnz` of each batch must be the same.
dtype of `crows` and `cols` must be int64, dtype of `values` can be float32 or float64.
key_padding_mask (DenseTensor|None, optional): The key padding mask tensor in the Attention module.
2D tensor with shape: [batch_size, seq_len]. dtype can be float32 or float64. Default: None.
attn_mask (DenseTensor|None, optional): The attention mask tensor in the Attention module.
2D tensor with shape: [seq_len, seq_len]. dtype can be float32 or float64. Default: None.
name (str|None, optional): The default value is None. Normally there is no need for user
to set this property. For more information, please refer to :ref:`api_guide_Name`.
Returns:
4D tensor with shape: [batch_size, num_heads, seq_len, head_dim]. dtype is same with input.
Examples:
.. code-block:: pycon
>>> # doctest: +REQUIRES(env:GPU)
>>> import paddle
>>> paddle.device.set_device('gpu')
>>> batch_size = 16
>>> num_heads = 16
>>> seq_len = 512
>>> head_dim = 32
>>> query = paddle.rand([batch_size, num_heads, seq_len, head_dim])
>>> key = paddle.rand([batch_size, num_heads, seq_len, head_dim])
>>> value = paddle.rand([batch_size, num_heads, seq_len, head_dim])
>>> query.stop_gradient = False
>>> key.stop_gradient = False
>>> value.stop_gradient = False
>>> mask = paddle.nn.functional.dropout(paddle.ones([seq_len, seq_len])).expand([batch_size, num_heads, seq_len, seq_len])
>>> sp_mask = mask.reshape([-1, seq_len, seq_len]).to_sparse_csr()
>>> kp_mask = paddle.randint(0, 2, [batch_size, seq_len]).astype(paddle.float32)
>>> attn_mask = paddle.randint(0, 2, [seq_len, seq_len]).astype(paddle.float32)
>>> output = paddle.sparse.nn.functional.attention(query, key, value, sp_mask, kp_mask, attn_mask)
>>> output.backward()
"""
assert in_dynamic_or_pir_mode(), (
"Currently, Sparse API only support dynamic mode or pir mode."
)
return _C_ops.sparse_fused_attention(
query, key, value, sparse_mask, key_padding_mask, attn_mask
)