masked_multihead_attention

paddle.incubate.nn.functional. masked_multihead_attention ( x, cache_kv=None, bias=None, src_mask=None, cum_offsets=None, sequence_lengths=None, rotary_tensor=None, beam_cache_offset=None, qkv_out_scale=None, out_shift=None, out_smooth=None, seq_len=1, rotary_emb_dims=0, use_neox_rotary_style=False, compute_dtype='default', out_scale=- 1, quant_round_type=1, quant_max_bound=127.0, quant_min_bound=- 127.0 ) [source]

Masked Multi-head attention for text summarization. This is a fusion operator to compute masked multi-head attention in transformer model architecture. This operator only supports running on GPU.

Parameters

  • x (Tensor) – The input tensor could be 2-D tensor. Its shape is [batch_size, 3 * num_head * head_dim].

  • cache_kvs (list(Tensor)|tuple(Tensor)) – The cache structure tensors for the generation model. Its shape is [2, batch_size, num_head, max_seq_len, head_dim].

  • bias (Tensor, optional) – The bias tensor. Its shape is [3, num_head, head_dim].

  • src_mask (Tensor, optional) – The src_mask tensor. Its shape is [batch_size, 1, 1, sequence_length].

  • sequence_lengths (Tensor, optional) – The sequence_lengths tensor, used to index input. Its shape is [batch_size, 1].

  • rotary_tensor (Tensor, optional) – The rotary_tensor tensor. The dtype must be float. Its shape is [batch_size, 1, 1, sequence_length, head_dim].

  • beam_cache_offset (Tensor, optional) – The beam_cache_offset tensor. Its shape is [batch_size, beam_size, max_seq_len + max_dec_len].

  • qkv_out_scale (Tensor, optional) – The qkv_out_scale tensor, used in quant. Its shape is [3, num_head, head_dim].

  • out_shift (Tensor, optional) – The out_shift tensor, used in quant.

  • out_smooth (Tensor, optional) – The out_smooth tensor, used in quant.

  • seq_len (int, optional) – The seq_len, used to get input length. Default 1.

  • rotary_emb_dims (int, optional) – The rotary_emb_dims. Default 1.

  • use_neox_rotary_style (bool, optional) – A flag indicating whether neox_rotary_style is needed or not. Default False.

  • compute_dtype (string) – A compute dtype, used to represent the input data type.

  • out_scale (float, optional) – The out_scale, used in quant.

  • quant_round_type (int, optional) – The quant_round_type, used in quant. Default 1.

  • quant_max_bound (float, optional) – The quant_max_bound, used in quant. Default 127.0.

  • quant_min_bound (float, optional) – The quant_min_bound, used in quant. Default -127.0.

Returns

If “beam_cache_offset_out” is not none, return the tuple (output, cache_kvs_out, beam_cache_offset_out), which output is the output of masked_multihead_attention layers, cache_kvs_out is inplace with input cache_kvs. If “beam_cache_offset_out” is none, return the tuple (output, cache_kvs_out).

Return type

Tensor|tuple

Examples

>>> 
>>> import paddle
>>> import paddle.incubate.nn.functional as F
>>> paddle.device.set_device('gpu')

>>> # input: [batch_size, 3 * num_head * dim_head]
>>> x = paddle.rand(shape=(2, 3 * 32 * 128), dtype="float32")

>>> # src_mask: [batch_size, 1, 1, sequence_length]
>>> src_mask = paddle.rand(shape=(2, 1, 1, 10), dtype="float32")

>>> # cache_kv: [2, batch_size, num_head, max_seq_len, dim_head]
>>> cache_kv = paddle.rand(shape=(2, 2, 32, 64, 128), dtype="float32")

>>> output = F.masked_multihead_attention(
...     x, src_mask=src_mask, cache_kv=cache_kv)