luanbei commited on
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1ffd7b5
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verified ·
1 Parent(s): 2a2abbb

Delete backbone

Browse files
backbone/bert_layers.py DELETED
@@ -1,912 +0,0 @@
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- # Copyright 2022 MosaicML Examples authors
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- # SPDX-License-Identifier: Apache-2.0
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-
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- # Copyright 2018 The Google AI Language Team Authors and The HuggingFace Inc. team.
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- # Copyright (c) 2018-2021, NVIDIA CORPORATION. All rights reserved.
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- # Copyright (c) 2022, Tri Dao.
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-
8
- import copy
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- import logging
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- import math
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- import warnings
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- from typing import List, Optional, Tuple, Union
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-
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- import torch
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- import torch.nn as nn
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- from einops import rearrange
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- from torch.nn.modules.utils import consume_prefix_in_state_dict_if_present
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- from transformers.activations import ACT2FN
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- from transformers.modeling_outputs import (MaskedLMOutput,
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- SequenceClassifierOutput)
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- from transformers.models.bert.modeling_bert import BertPreTrainedModel
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- from transformers.modeling_utils import PreTrainedModel
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-
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- from .bert_padding import (index_first_axis,
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- index_put_first_axis, pad_input,
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- unpad_input, unpad_input_only)
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-
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- try:
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- from .flash_attn_triton import flash_attn_qkvpacked_func
30
- except ImportError as e:
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- flash_attn_qkvpacked_func = None
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-
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- logger = logging.getLogger(__name__)
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-
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-
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- class BertEmbeddings(nn.Module):
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-
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- def __init__(self, config):
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- super().__init__()
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- self.word_embeddings = nn.Embedding(config.vocab_size,
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- config.hidden_size,
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- padding_idx=config.pad_token_id)
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- # ALiBi doesn't use position embeddings
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- self.token_type_embeddings = nn.Embedding(config.type_vocab_size,
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- config.hidden_size)
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-
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- # self.LayerNorm is not snake-cased to stick with TensorFlow model
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- # variable name and be able to load any TensorFlow checkpoint file
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- self.LayerNorm = nn.LayerNorm(config.hidden_size,
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- eps=config.layer_norm_eps)
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- self.dropout = nn.Dropout(config.hidden_dropout_prob)
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- self.register_buffer('token_type_ids',
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- torch.zeros(config.max_position_embeddings,
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- dtype=torch.long),
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- persistent=False)
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-
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- def forward(
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- self,
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- input_ids: Optional[torch.LongTensor] = None,
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- token_type_ids: Optional[torch.LongTensor] = None,
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- position_ids: Optional[torch.LongTensor] = None,
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- inputs_embeds: Optional[torch.FloatTensor] = None,
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- past_key_values_length: int = 0,
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- ) -> torch.Tensor:
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- if (input_ids is not None) == (inputs_embeds is not None):
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- raise ValueError('Must specify either input_ids or input_embeds!')
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- if input_ids is not None:
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- input_shape = input_ids.size()
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- else:
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- assert inputs_embeds is not None # just for type checking
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- input_shape = inputs_embeds.size()[:-1]
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-
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- seq_length = input_shape[1]
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-
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- if position_ids is None:
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- # great! ALiBi
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- pass
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-
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- # Setting the token_type_ids to the registered buffer in constructor
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- # where it is all zeros, which usually occurs when it's auto-generated;
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- # registered buffer helps users when tracing the model without passing
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- # token_type_ids, solves issue #5664
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- if token_type_ids is None:
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- if hasattr(self, 'token_type_ids'):
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- assert isinstance(self.token_type_ids, torch.LongTensor)
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- buffered_token_type_ids = self.token_type_ids[:, :seq_length]
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- buffered_token_type_ids_expanded = buffered_token_type_ids.expand(
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- input_shape[0], seq_length)
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- token_type_ids = buffered_token_type_ids_expanded # type: ignore
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- else:
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- token_type_ids = torch.zeros(input_shape, # type: ignore
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- dtype=torch.long,
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- device=self.word_embeddings.device) # type: ignore # yapf: disable
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-
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- if inputs_embeds is None:
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- inputs_embeds = self.word_embeddings(input_ids)
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- token_type_embeddings = self.token_type_embeddings(token_type_ids)
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-
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- embeddings = inputs_embeds + token_type_embeddings
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- # no position embeddings! ALiBi
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- embeddings = self.LayerNorm(embeddings)
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- embeddings = self.dropout(embeddings)
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- return embeddings
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-
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-
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- class BertUnpadSelfAttention(nn.Module):
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-
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- def __init__(self, config):
109
- super().__init__()
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- if config.hidden_size % config.num_attention_heads != 0 and not hasattr(
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- config, 'embedding_size'):
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- raise ValueError(
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- f'The hidden size ({config.hidden_size}) is not a multiple of the number of attention '
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- f'heads ({config.num_attention_heads})')
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-
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- self.num_attention_heads = config.num_attention_heads
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- self.attention_head_size = int(config.hidden_size /
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- config.num_attention_heads)
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- self.all_head_size = self.num_attention_heads * self.attention_head_size
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- self.dropout = nn.Dropout(config.attention_probs_dropout_prob)
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- self.p_dropout = config.attention_probs_dropout_prob
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- self.Wqkv = nn.Linear(self.all_head_size, 3 * config.hidden_size)
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-
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- # Warn if defaulting to pytorch because of import issues
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- if flash_attn_qkvpacked_func is None:
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- warnings.warn(
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- 'Unable to import Triton; defaulting MosaicBERT attention implementation to pytorch (this will reduce throughput when using this model).'
128
- )
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-
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- def forward(self, hidden_states: torch.Tensor, cu_seqlens: torch.Tensor,
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- max_seqlen_in_batch: int, indices: torch.Tensor,
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- attn_mask: torch.Tensor, bias: torch.Tensor) -> torch.Tensor:
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- """Perform self-attention.
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-
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- If dropout is zero, then we can use the Triton kernel, so we do that. However, if not, we send through a standard PyTorch
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- implementation of self-attention.
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-
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- The arguments are unpadded, and our implementations of attention require padded arguments,
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- so we first call `pad_input`. Once we compute attention, we re-unpad our outputs for the other layers.
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- The pad/unpad operations add overhead, but not sending pad tokens through ffs saves compute.
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- It is possible to write an unpadded implementation of attention (in Triton and PyTorch), which we will eventually do.
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-
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- Args:
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- hidden_states: (total_nnz, dim)
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- cu_seqlens: (batch + 1,)
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- max_seqlen_in_batch: int
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- indices: (total_nnz,)
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- attn_mask: (batch, max_seqlen_in_batch)
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- bias: (batch, heads, max_seqlen_in_batch, max_seqlen_in_batch)
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-
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- Returns:
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- attention: (total_nnz, dim)
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- """
154
- qkv = self.Wqkv(hidden_states)
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- qkv = pad_input(qkv, indices, cu_seqlens.shape[0] - 1,
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- max_seqlen_in_batch) # batch, max_seqlen_in_batch, thd
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- qkv = rearrange(qkv,
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- 'b s (t h d) -> b s t h d',
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- t=3,
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- h=self.num_attention_heads)
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- if self.p_dropout or flash_attn_qkvpacked_func is None:
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- # if we have nonzero attention dropout (e.g. during fine-tuning) or no Triton, compute attention in PyTorch
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- q = qkv[:, :, 0, :, :].permute(0, 2, 1, 3) # b h s d
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- k = qkv[:, :, 1, :, :].permute(0, 2, 3, 1) # b h d s
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- v = qkv[:, :, 2, :, :].permute(0, 2, 1, 3) # b h s d
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- attention_scores = torch.matmul(q, k) / math.sqrt(
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- self.attention_head_size)
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- attention_scores = attention_scores + bias
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- attention_probs = nn.functional.softmax(attention_scores, dim=-1)
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- attention_probs = self.dropout(attention_probs)
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- attention = torch.matmul(attention_probs, v).permute(0, 2, 1,
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- 3) # b s h d
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- else:
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- # Triton implementation only supports 0 attention dropout
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- convert_dtype = qkv.dtype not in [torch.float16, torch.bfloat16]
176
- if convert_dtype:
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- # Triton implementation only supports fp16 and bf16
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- orig_dtype = qkv.dtype
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- qkv = qkv.to(torch.float16)
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- bias_dtype = bias.dtype
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- bias = bias.to(torch.float16)
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- attention = flash_attn_qkvpacked_func(qkv, bias)
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- attention = attention.to(orig_dtype)
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- bias = bias.to(bias_dtype)
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- else:
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- attention = flash_attn_qkvpacked_func(qkv, bias)
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-
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- # attn_mask is 1 for attend and 0 for don't
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- attention = unpad_input_only(attention, torch.squeeze(attn_mask) == 1)
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- return rearrange(attention, 'nnz h d -> nnz (h d)')
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-
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-
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- # Copy of transformer's library BertSelfOutput that will not be caught by surgery methods looking for HF BERT modules.
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- class BertSelfOutput(nn.Module):
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-
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- def __init__(self, config):
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- super().__init__()
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- self.dense = nn.Linear(config.hidden_size, config.hidden_size)
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- self.LayerNorm = nn.LayerNorm(config.hidden_size,
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- eps=config.layer_norm_eps)
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- self.dropout = nn.Dropout(config.hidden_dropout_prob)
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-
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- def forward(self, hidden_states: torch.Tensor,
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- input_tensor: torch.Tensor) -> torch.Tensor:
205
- hidden_states = self.dense(hidden_states)
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- hidden_states = self.dropout(hidden_states)
207
- hidden_states = self.LayerNorm(hidden_states + input_tensor)
208
- return hidden_states
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-
210
-
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- class BertUnpadAttention(nn.Module):
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- """Chains attention, Dropout, and LayerNorm for Mosaic BERT."""
213
-
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- def __init__(self, config):
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- super().__init__()
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- self.self = BertUnpadSelfAttention(config)
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- self.output = BertSelfOutput(config)
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-
219
- def forward(
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- self,
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- input_tensor: torch.Tensor,
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- cu_seqlens: torch.Tensor,
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- max_s: int,
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- subset_idx: Optional[torch.Tensor] = None,
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- indices: Optional[torch.Tensor] = None,
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- attn_mask: Optional[torch.Tensor] = None,
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- bias: Optional[torch.Tensor] = None,
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- ) -> torch.Tensor:
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- """Forward pass for scaled self-attention without padding.
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-
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- Arguments:
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- input_tensor: (total_nnz, dim)
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- cu_seqlens: (batch + 1,)
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- max_s: int
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- subset_idx: () set of indices whose values we care about at the end of the layer
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- (e.g., the masked tokens, if this is the final layer).
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- indices: None or (total_nnz,)
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- attn_mask: None or (batch, max_seqlen_in_batch)
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- bias: None or (batch, heads, max_seqlen_in_batch, max_seqlen_in_batch)
240
- """
241
- self_output = self.self(input_tensor, cu_seqlens, max_s, indices,
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- attn_mask, bias)
243
- if subset_idx is not None:
244
- return self.output(index_first_axis(self_output, subset_idx),
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- index_first_axis(input_tensor, subset_idx))
246
- else:
247
- return self.output(self_output, input_tensor)
248
-
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-
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- class BertGatedLinearUnitMLP(nn.Module):
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- """Applies the FFN at the end of each Mosaic BERT layer.
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-
253
- Compared to the default BERT architecture, this block replaces :class:`~transformers.model.bert.modeling_bert.BertIntermediate`
254
- and :class:`~transformers.model.bert.modeling_bert.SelfOutput` with a single module that has similar functionality, but
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- introduces Gated Linear Units.
256
-
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- Note: Mosaic BERT adds parameters in order to implement Gated Linear Units. To keep parameter count consistent with that of a
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- standard Hugging Face BERT, scale down `config.intermediate_size` by 2/3. For example, a Mosaic BERT constructed with
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- `config.intermediate_size=2048` will have the same parameter footprint as its Hugging Face BERT counterpart constructed
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- with the `config.intermediate_size=3072`.
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- However, in most cases it will not be necessary to adjust `config.intermediate_size` since, despite the increased
262
- parameter size, Mosaic BERT typically offers a net higher throughput than a Hugging Face BERT built from the same `config`.
263
- """
264
-
265
- def __init__(self, config):
266
- super().__init__()
267
- self.config = config
268
- self.gated_layers = nn.Linear(config.hidden_size,
269
- config.intermediate_size * 2,
270
- bias=False)
271
- self.act = nn.GELU(approximate='none')
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- self.wo = nn.Linear(config.intermediate_size, config.hidden_size)
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- self.dropout = nn.Dropout(config.hidden_dropout_prob)
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- self.layernorm = nn.LayerNorm(config.hidden_size,
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- eps=config.layer_norm_eps)
276
-
277
- def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
278
- """Compute new hidden states from current hidden states.
279
-
280
- Args:
281
- hidden_states (torch.Tensor): The (unpadded) hidden states from
282
- the attention layer [nnz, dim].
283
- """
284
- residual_connection = hidden_states
285
- # compute the activation
286
- hidden_states = self.gated_layers(hidden_states)
287
- gated = hidden_states[:, :self.config.intermediate_size]
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- non_gated = hidden_states[:, self.config.intermediate_size:]
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- hidden_states = self.act(gated) * non_gated
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- hidden_states = self.dropout(hidden_states)
291
- # multiply by the second matrix
292
- hidden_states = self.wo(hidden_states)
293
- # add the residual connection and post-LN
294
- hidden_states = self.layernorm(hidden_states + residual_connection)
295
- return hidden_states
296
-
297
-
298
- class BertLayer(nn.Module):
299
- """Composes the Mosaic BERT attention and FFN blocks into a single layer."""
300
-
301
- def __init__(self, config):
302
- super(BertLayer, self).__init__()
303
- self.attention = BertUnpadAttention(config)
304
- self.mlp = BertGatedLinearUnitMLP(config)
305
-
306
- def forward(
307
- self,
308
- hidden_states: torch.Tensor,
309
- cu_seqlens: torch.Tensor,
310
- seqlen: int,
311
- subset_idx: Optional[torch.Tensor] = None,
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- indices: Optional[torch.Tensor] = None,
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- attn_mask: Optional[torch.Tensor] = None,
314
- bias: Optional[torch.Tensor] = None,
315
- ) -> torch.Tensor:
316
- """Forward pass for a BERT layer, including both attention and MLP.
317
-
318
- Args:
319
- hidden_states: (total_nnz, dim)
320
- cu_seqlens: (batch + 1,)
321
- seqlen: int
322
- subset_idx: () set of indices whose values we care about at the end of the layer
323
- (e.g., the masked tokens, if this is the final layer).
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- indices: None or (total_nnz,)
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- attn_mask: None or (batch, max_seqlen_in_batch)
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- bias: None or (batch, heads, max_seqlen_in_batch, max_seqlen_in_batch)
327
- """
328
- attention_output = self.attention(hidden_states, cu_seqlens, seqlen,
329
- subset_idx, indices, attn_mask, bias)
330
- layer_output = self.mlp(attention_output)
331
- return layer_output
332
-
333
-
334
- class BertEncoder(nn.Module):
335
- """A stack of BERT layers providing the backbone of Mosaic BERT.
336
-
337
- This module is modeled after the Hugging Face BERT's :class:`~transformers.model.bert.modeling_bert.BertEncoder`,
338
- but with substantial modifications to implement unpadding and ALiBi.
339
-
340
- Compared to the analogous Hugging Face BERT module, this module handles unpadding to reduce unnecessary computation
341
- at padded tokens, and pre-computes attention biases to implement ALiBi.
342
- """
343
-
344
- def __init__(self, config):
345
- super().__init__()
346
- layer = BertLayer(config)
347
- self.layer = nn.ModuleList(
348
- [copy.deepcopy(layer) for _ in range(config.num_hidden_layers)])
349
-
350
- self.num_attention_heads = config.num_attention_heads
351
-
352
- # The alibi mask will be dynamically expanded if it is too small for
353
- # the input the model receives. But it generally helps to initialize it
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- # to a reasonably large size to help pre-allocate CUDA memory.
355
- # The default `alibi_starting_size` is 512.
356
- self._current_alibi_size = int(config.alibi_starting_size)
357
- self.alibi = torch.zeros(
358
- (1, self.num_attention_heads, self._current_alibi_size,
359
- self._current_alibi_size))
360
- self.rebuild_alibi_tensor(size=config.alibi_starting_size)
361
-
362
- def rebuild_alibi_tensor(self,
363
- size: int,
364
- device: Optional[Union[torch.device, str]] = None):
365
- # Alibi
366
- # Following https://github.com/ofirpress/attention_with_linear_biases/issues/5 (Implementation 1)
367
- # In the causal case, you can exploit the fact that softmax is invariant to a uniform translation
368
- # of the logits, which makes the math work out *after* applying causal masking. If no causal masking
369
- # will be applied, it is necessary to construct the diagonal mask.
370
- n_heads = self.num_attention_heads
371
-
372
- def _get_alibi_head_slopes(n_heads: int) -> List[float]:
373
-
374
- def get_slopes_power_of_2(n_heads: int) -> List[float]:
375
- start = (2**(-2**-(math.log2(n_heads) - 3)))
376
- ratio = start
377
- return [start * ratio**i for i in range(n_heads)]
378
-
379
- # In the paper, they only train models that have 2^a heads for some a. This function
380
- # has some good properties that only occur when the input is a power of 2. To
381
- # maintain that even when the number of heads is not a power of 2, we use a
382
- # workaround.
383
- if math.log2(n_heads).is_integer():
384
- return get_slopes_power_of_2(n_heads)
385
-
386
- closest_power_of_2 = 2**math.floor(math.log2(n_heads))
387
- slopes_a = get_slopes_power_of_2(closest_power_of_2)
388
- slopes_b = _get_alibi_head_slopes(2 * closest_power_of_2)
389
- slopes_b = slopes_b[0::2][:n_heads - closest_power_of_2]
390
- return slopes_a + slopes_b
391
-
392
- context_position = torch.arange(size, device=device)[:, None]
393
- memory_position = torch.arange(size, device=device)[None, :]
394
- relative_position = torch.abs(memory_position - context_position)
395
- # [n_heads, max_token_length, max_token_length]
396
- relative_position = relative_position.unsqueeze(0).expand(
397
- n_heads, -1, -1)
398
- slopes = torch.Tensor(_get_alibi_head_slopes(n_heads)).to(device)
399
- alibi = slopes.unsqueeze(1).unsqueeze(1) * -relative_position
400
- # [1, n_heads, max_token_length, max_token_length]
401
- alibi = alibi.unsqueeze(0)
402
- assert alibi.shape == torch.Size([1, n_heads, size, size])
403
-
404
- self._current_alibi_size = size
405
- self.alibi = alibi
406
-
407
- def forward(
408
- self,
409
- hidden_states: torch.Tensor,
410
- attention_mask: torch.Tensor,
411
- output_all_encoded_layers: Optional[bool] = True,
412
- subset_mask: Optional[torch.Tensor] = None,
413
- ) -> List[torch.Tensor]:
414
-
415
- extended_attention_mask = attention_mask.unsqueeze(1).unsqueeze(2)
416
- extended_attention_mask = extended_attention_mask.to(
417
- dtype=torch.float32) # fp16 compatibility
418
- extended_attention_mask = (1.0 - extended_attention_mask) * -10000.0
419
-
420
- attention_mask_bool = attention_mask.bool()
421
- batch, seqlen = hidden_states.shape[:2]
422
- # Unpad inputs and mask. It will remove tokens that are padded.
423
- # Assume ntokens is total number of tokens (padded and non-padded)
424
- # and ntokens_unpad is total number of non-padded tokens.
425
- # Then unpadding performs the following compression of the inputs:
426
- # hidden_states[ntokens,hidden] -> hidden_states[ntokens_unpad,hidden]
427
- hidden_states, indices, cu_seqlens, _ = unpad_input(
428
- hidden_states, attention_mask_bool)
429
-
430
- # Add alibi matrix to extended_attention_mask
431
- if self._current_alibi_size < seqlen:
432
- # Rebuild the alibi tensor when needed
433
- warnings.warn(
434
- f'Increasing alibi size from {self._current_alibi_size} to {seqlen}'
435
- )
436
- self.rebuild_alibi_tensor(size=seqlen, device=hidden_states.device)
437
- elif self.alibi.device != hidden_states.device:
438
- # Device catch-up
439
- self.alibi = self.alibi.to(hidden_states.device)
440
- alibi_bias = self.alibi[:, :, :seqlen, :seqlen]
441
- attn_bias = extended_attention_mask[:, :, :seqlen, :seqlen]
442
- alibi_attn_mask = attn_bias + alibi_bias
443
-
444
- all_encoder_layers = []
445
- if subset_mask is None:
446
- for layer_module in self.layer:
447
- hidden_states = layer_module(hidden_states,
448
- cu_seqlens,
449
- seqlen,
450
- None,
451
- indices,
452
- attn_mask=attention_mask,
453
- bias=alibi_attn_mask)
454
- if output_all_encoded_layers:
455
- all_encoder_layers.append(hidden_states)
456
- # Pad inputs and mask. It will insert back zero-padded tokens.
457
- # Assume ntokens is total number of tokens (padded and non-padded)
458
- # and ntokens_unpad is total number of non-padded tokens.
459
- # Then padding performs the following de-compression:
460
- # hidden_states[ntokens_unpad,hidden] -> hidden_states[ntokens,hidden]
461
- hidden_states = pad_input(hidden_states, indices, batch, seqlen)
462
- else:
463
- for i in range(len(self.layer) - 1):
464
- layer_module = self.layer[i]
465
- hidden_states = layer_module(hidden_states,
466
- cu_seqlens,
467
- seqlen,
468
- None,
469
- indices,
470
- attn_mask=attention_mask,
471
- bias=alibi_attn_mask)
472
- if output_all_encoded_layers:
473
- all_encoder_layers.append(hidden_states)
474
- subset_idx = torch.nonzero(subset_mask[attention_mask_bool],
475
- as_tuple=False).flatten()
476
- hidden_states = self.layer[-1](hidden_states,
477
- cu_seqlens,
478
- seqlen,
479
- subset_idx=subset_idx,
480
- indices=indices,
481
- attn_mask=attention_mask,
482
- bias=alibi_attn_mask)
483
-
484
- if not output_all_encoded_layers:
485
- all_encoder_layers.append(hidden_states)
486
- return all_encoder_layers
487
-
488
-
489
- class BertPooler(nn.Module):
490
-
491
- def __init__(self, config):
492
- super(BertPooler, self).__init__()
493
- self.dense = nn.Linear(config.hidden_size, config.hidden_size)
494
- self.activation = nn.Tanh()
495
-
496
- def forward(self,
497
- hidden_states: torch.Tensor,
498
- pool: Optional[bool] = True) -> torch.Tensor:
499
- # We "pool" the model by simply taking the hidden state corresponding
500
- # to the first token.
501
- first_token_tensor = hidden_states[:, 0] if pool else hidden_states
502
- pooled_output = self.dense(first_token_tensor)
503
- pooled_output = self.activation(pooled_output)
504
- return pooled_output
505
-
506
-
507
- class BertPredictionHeadTransform(nn.Module):
508
-
509
- def __init__(self, config):
510
- super().__init__()
511
- self.dense = nn.Linear(config.hidden_size, config.hidden_size)
512
- if isinstance(config.hidden_act, str):
513
- self.transform_act_fn = ACT2FN[config.hidden_act]
514
- else:
515
- self.transform_act_fn = config.hidden_act
516
- self.LayerNorm = torch.nn.LayerNorm(config.hidden_size, eps=1e-12)
517
-
518
- def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
519
- hidden_states = self.dense(hidden_states)
520
- hidden_states = self.transform_act_fn(hidden_states)
521
- hidden_states = self.LayerNorm(hidden_states)
522
- return hidden_states
523
-
524
-
525
- class BertModel(BertPreTrainedModel):
526
- """Overall BERT model.
527
-
528
- Args:
529
- config: a BertConfig class instance with the configuration to build a new model
530
-
531
- Inputs:
532
- `input_ids`: a torch.LongTensor of shape [batch_size, sequence_length]
533
- with the word token indices in the vocabulary(see the tokens preprocessing logic in the scripts
534
- `extract_features.py`, `run_classifier.py` and `run_squad.py`)
535
- `token_type_ids`: an optional torch.LongTensor of shape [batch_size, sequence_length] with the token
536
- types indices selected in [0, 1]. Type 0 corresponds to a `sentence A` and type 1 corresponds to
537
- a `sentence B` token (see BERT paper for more details).
538
- `attention_mask`: an optional torch.LongTensor of shape [batch_size, sequence_length] with indices
539
- selected in [0, 1]. It's a mask to be used if the input sequence length is smaller than the max
540
- input sequence length in the current batch. It's the mask that we typically use for attention when
541
- a batch has varying length sentences.
542
- `output_all_encoded_layers`: boolean which controls the content of the `encoded_layers` output as described below. Default: `True`.
543
-
544
- Outputs: Tuple of (encoded_layers, pooled_output)
545
- `encoded_layers`: controlled by `output_all_encoded_layers` argument:
546
- - `output_all_encoded_layers=True`: outputs a list of the full sequences of encoded-hidden-states at the end
547
- of each attention block (i.e. 12 full sequences for BERT-base, 24 for BERT-large), each
548
- encoded-hidden-state is a torch.FloatTensor of size [batch_size, sequence_length, hidden_size],
549
- - `output_all_encoded_layers=False`: outputs only the full sequence of hidden-states corresponding
550
- to the last attention block of shape [batch_size, sequence_length, hidden_size],
551
- `pooled_output`: a torch.FloatTensor of size [batch_size, hidden_size] which is the output of a
552
- classifier pretrained on top of the hidden state associated to the first character of the
553
- input (`CLS`) to train on the Next-Sentence task (see BERT's paper).
554
-
555
- Example usage:
556
- ```python
557
- # Already been converted into WordPiece token ids
558
- input_ids = torch.LongTensor([[31, 51, 99], [15, 5, 0]])
559
- input_mask = torch.LongTensor([[1, 1, 1], [1, 1, 0]])
560
- token_type_ids = torch.LongTensor([[0, 0, 1], [0, 1, 0]])
561
- config = modeling.BertConfig(vocab_size_or_config_json_file=32000, hidden_size=768,
562
- num_hidden_layers=12, num_attention_heads=12, intermediate_size=3072)
563
- model = BertModel(config=config)
564
- all_encoder_layers, pooled_output = model(input_ids, token_type_ids, input_mask)
565
- ```
566
- """
567
-
568
- def __init__(self, config, add_pooling_layer=True):
569
- super(BertModel, self).__init__(config)
570
- self.embeddings = BertEmbeddings(config)
571
- self.encoder = BertEncoder(config)
572
- self.pooler = BertPooler(config) if add_pooling_layer else None
573
- self.post_init()
574
-
575
- def get_input_embeddings(self):
576
- return self.embeddings.word_embeddings
577
-
578
- def set_input_embeddings(self, value):
579
- self.embeddings.word_embeddings = value
580
-
581
- def forward(
582
- self,
583
- input_ids: torch.Tensor,
584
- token_type_ids: Optional[torch.Tensor] = None,
585
- attention_mask: Optional[torch.Tensor] = None,
586
- position_ids: Optional[torch.Tensor] = None,
587
- output_all_encoded_layers: Optional[bool] = False,
588
- masked_tokens_mask: Optional[torch.Tensor] = None,
589
- **kwargs
590
- ) -> Tuple[Union[List[torch.Tensor], torch.Tensor], Optional[torch.Tensor]]:
591
- if attention_mask is None:
592
- attention_mask = torch.ones_like(input_ids)
593
- if token_type_ids is None:
594
- token_type_ids = torch.zeros_like(input_ids)
595
-
596
- embedding_output = self.embeddings(input_ids, token_type_ids,
597
- position_ids)
598
-
599
- subset_mask = []
600
- first_col_mask = []
601
-
602
- if masked_tokens_mask is None:
603
- subset_mask = None
604
- else:
605
- first_col_mask = torch.zeros_like(masked_tokens_mask)
606
- first_col_mask[:, 0] = True
607
- subset_mask = masked_tokens_mask | first_col_mask
608
-
609
- encoder_outputs = self.encoder(
610
- embedding_output,
611
- attention_mask,
612
- output_all_encoded_layers=output_all_encoded_layers,
613
- subset_mask=subset_mask)
614
-
615
- if masked_tokens_mask is None:
616
- sequence_output = encoder_outputs[-1]
617
- pooled_output = self.pooler(
618
- sequence_output) if self.pooler is not None else None
619
- else:
620
- # TD [2022-03-01]: the indexing here is very tricky.
621
- attention_mask_bool = attention_mask.bool()
622
- subset_idx = subset_mask[attention_mask_bool] # type: ignore
623
- sequence_output = encoder_outputs[-1][
624
- masked_tokens_mask[attention_mask_bool][subset_idx]]
625
- if self.pooler is not None:
626
- pool_input = encoder_outputs[-1][
627
- first_col_mask[attention_mask_bool][subset_idx]]
628
- pooled_output = self.pooler(pool_input, pool=False)
629
- else:
630
- pooled_output = None
631
-
632
- if not output_all_encoded_layers:
633
- encoder_outputs = sequence_output
634
-
635
- if self.pooler is not None:
636
- return encoder_outputs, pooled_output
637
-
638
- return encoder_outputs, None
639
-
640
-
641
- ###################
642
- # Bert Heads
643
- ###################
644
- class BertLMPredictionHead(nn.Module):
645
-
646
- def __init__(self, config, bert_model_embedding_weights):
647
- super().__init__()
648
- self.transform = BertPredictionHeadTransform(config)
649
- # The output weights are the same as the input embeddings, but there is
650
- # an output-only bias for each token.
651
- self.decoder = nn.Linear(bert_model_embedding_weights.size(1),
652
- bert_model_embedding_weights.size(0))
653
- self.decoder.weight = bert_model_embedding_weights
654
-
655
- def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
656
- hidden_states = self.transform(hidden_states)
657
- hidden_states = self.decoder(hidden_states)
658
- return hidden_states
659
-
660
-
661
- class BertOnlyMLMHead(nn.Module):
662
-
663
- def __init__(self, config, bert_model_embedding_weights):
664
- super().__init__()
665
- self.predictions = BertLMPredictionHead(config,
666
- bert_model_embedding_weights)
667
-
668
- def forward(self, sequence_output: torch.Tensor) -> torch.Tensor:
669
- prediction_scores = self.predictions(sequence_output)
670
- return prediction_scores
671
-
672
-
673
- class BertOnlyNSPHead(nn.Module):
674
-
675
- def __init__(self, config):
676
- super().__init__()
677
- self.seq_relationship = nn.Linear(config.hidden_size, 2)
678
-
679
- def forward(self, pooled_output: torch.Tensor) -> torch.Tensor:
680
- seq_relationship_score = self.seq_relationship(pooled_output)
681
- return seq_relationship_score
682
-
683
-
684
-
685
- class BertForMaskedLM(BertPreTrainedModel):
686
-
687
- def __init__(self, config):
688
- super().__init__(config)
689
-
690
- if config.is_decoder:
691
- warnings.warn(
692
- 'If you want to use `BertForMaskedLM` make sure `config.is_decoder=False` for '
693
- 'bi-directional self-attention.')
694
-
695
- self.bert = BertModel(config, add_pooling_layer=False)
696
- self.cls = BertOnlyMLMHead(config,
697
- self.bert.embeddings.word_embeddings.weight)
698
-
699
- # Initialize weights and apply final processing
700
- self.post_init()
701
-
702
- def get_output_embeddings(self):
703
- return self.cls.predictions.decoder
704
-
705
- def set_output_embeddings(self, new_embeddings):
706
- self.cls.predictions.decoder = new_embeddings
707
-
708
- def forward(
709
- self,
710
- input_ids: Optional[torch.Tensor] = None,
711
- attention_mask: Optional[torch.Tensor] = None,
712
- token_type_ids: Optional[torch.Tensor] = None,
713
- position_ids: Optional[torch.Tensor] = None,
714
- head_mask: Optional[torch.Tensor] = None,
715
- inputs_embeds: Optional[torch.Tensor] = None,
716
- encoder_hidden_states: Optional[torch.Tensor] = None,
717
- encoder_attention_mask: Optional[torch.Tensor] = None,
718
- labels: Optional[torch.Tensor] = None,
719
- output_attentions: Optional[bool] = None,
720
- output_hidden_states: Optional[bool] = None,
721
- return_dict: Optional[bool] = None,
722
- ) -> Union[Tuple[torch.Tensor], MaskedLMOutput]:
723
- # labels should be a `torch.LongTensor` of shape
724
- # `(batch_size, sequence_length)`. These are used for computing the
725
- # masked language modeling loss.
726
- #
727
- # Indices should be in `[-100, 0, ..., config.vocab_size]` (see
728
- # `input_ids` docstring) Tokens with indices set to `-100` are ignored
729
- # (masked), the loss is only computed for the tokens with labels in `[0,
730
- # ..., config.vocab_size]`
731
- #
732
- # Prediction scores are only computed for masked tokens and the (bs,
733
- # seqlen) dimensions are flattened
734
- if (input_ids is not None) == (inputs_embeds is not None):
735
- raise ValueError('Must specify either input_ids or input_embeds!')
736
-
737
- if labels is None:
738
- masked_tokens_mask = None
739
- else:
740
- masked_tokens_mask = labels > 0
741
-
742
- return_dict = return_dict if return_dict is not None else self.config.use_return_dict
743
-
744
- outputs = self.bert(
745
- input_ids,
746
- attention_mask=attention_mask,
747
- token_type_ids=token_type_ids,
748
- position_ids=position_ids,
749
- head_mask=head_mask,
750
- inputs_embeds=inputs_embeds,
751
- encoder_hidden_states=encoder_hidden_states,
752
- encoder_attention_mask=encoder_attention_mask,
753
- output_attentions=output_attentions,
754
- output_hidden_states=output_hidden_states,
755
- return_dict=return_dict,
756
- masked_tokens_mask=masked_tokens_mask,
757
- )
758
-
759
- sequence_output = outputs[0]
760
- prediction_scores = self.cls(sequence_output)
761
-
762
- loss = None
763
- if labels is not None:
764
- # Compute loss
765
- loss_fct = nn.CrossEntropyLoss()
766
- masked_token_idx = torch.nonzero(labels.flatten() > 0,
767
- as_tuple=False).flatten()
768
- loss = loss_fct(prediction_scores,
769
- labels.flatten()[masked_token_idx])
770
-
771
- assert input_ids is not None, 'Coding error; please open an issue'
772
- batch, seqlen = input_ids.shape[:2]
773
- prediction_scores = rearrange(index_put_first_axis(
774
- prediction_scores, masked_token_idx, batch * seqlen),
775
- '(b s) d -> b s d',
776
- b=batch)
777
-
778
- if not return_dict:
779
- output = (prediction_scores,) + outputs[2:]
780
- return ((loss,) + output) if loss is not None else output
781
-
782
- return MaskedLMOutput(
783
- loss=loss,
784
- logits=prediction_scores,
785
- hidden_states=outputs[0],
786
- attentions=None,
787
- )
788
-
789
- def prepare_inputs_for_generation(self, input_ids: torch.Tensor,
790
- attention_mask: torch.Tensor,
791
- **model_kwargs):
792
- input_shape = input_ids.shape
793
- effective_batch_size = input_shape[0]
794
-
795
- # add a dummy token
796
- if self.config.pad_token_id is None:
797
- raise ValueError('The PAD token should be defined for generation')
798
-
799
- attention_mask = torch.cat([
800
- attention_mask,
801
- attention_mask.new_zeros((attention_mask.shape[0], 1))
802
- ],
803
- dim=-1)
804
- dummy_token = torch.full((effective_batch_size, 1),
805
- self.config.pad_token_id,
806
- dtype=torch.long,
807
- device=input_ids.device)
808
- input_ids = torch.cat([input_ids, dummy_token], dim=1)
809
-
810
- return {'input_ids': input_ids, 'attention_mask': attention_mask}
811
-
812
-
813
-
814
- class BertForSequenceClassification(BertPreTrainedModel):
815
- """Bert Model transformer with a sequence classification/regression head.
816
-
817
- This head is just a linear layer on top of the pooled output. Used for,
818
- e.g., GLUE tasks.
819
- """
820
-
821
- def __init__(self, config):
822
- super().__init__(config)
823
- self.num_labels = config.num_labels
824
- self.config = config
825
-
826
- self.bert = BertModel(config)
827
- classifier_dropout = (config.classifier_dropout
828
- if config.classifier_dropout is not None else
829
- config.hidden_dropout_prob)
830
- self.dropout = nn.Dropout(classifier_dropout)
831
- self.classifier = nn.Linear(config.hidden_size, config.num_labels)
832
-
833
- # Initialize weights and apply final processing
834
- self.post_init()
835
-
836
-
837
- def forward(
838
- self,
839
- input_ids: Optional[torch.Tensor] = None,
840
- attention_mask: Optional[torch.Tensor] = None,
841
- token_type_ids: Optional[torch.Tensor] = None,
842
- position_ids: Optional[torch.Tensor] = None,
843
- head_mask: Optional[torch.Tensor] = None,
844
- inputs_embeds: Optional[torch.Tensor] = None,
845
- labels: Optional[torch.Tensor] = None,
846
- output_attentions: Optional[bool] = None,
847
- output_hidden_states: Optional[bool] = None,
848
- return_dict: Optional[bool] = None,
849
- ) -> Union[Tuple[torch.Tensor], SequenceClassifierOutput]:
850
- # labels (`torch.LongTensor` of shape `(batch_size,)`, *optional*):
851
- # Labels for computing the sequence classification/regression loss.
852
- # Indices should be in `[0, ..., config.num_labels - 1]`.
853
- # If `config.num_labels == 1` a regression loss is computed
854
- # (mean-square loss). If `config.num_labels > 1` a classification loss
855
- # is computed (cross-entropy).
856
-
857
- return_dict = return_dict if return_dict is not None else self.config.use_return_dict
858
-
859
- outputs = self.bert(
860
- input_ids,
861
- attention_mask=attention_mask,
862
- token_type_ids=token_type_ids,
863
- position_ids=position_ids,
864
- head_mask=head_mask,
865
- inputs_embeds=inputs_embeds,
866
- output_attentions=output_attentions,
867
- output_hidden_states=output_hidden_states,
868
- return_dict=return_dict,
869
- )
870
-
871
- pooled_output = outputs[1]
872
-
873
- pooled_output = self.dropout(pooled_output)
874
- logits = self.classifier(pooled_output)
875
-
876
- loss = None
877
- if labels is not None:
878
- # Compute loss
879
- if self.config.problem_type is None:
880
- if self.num_labels == 1:
881
- self.config.problem_type = 'regression'
882
- elif self.num_labels > 1 and (labels.dtype == torch.long or
883
- labels.dtype == torch.int):
884
- self.config.problem_type = 'single_label_classification'
885
- else:
886
- self.config.problem_type = 'multi_label_classification'
887
-
888
- if self.config.problem_type == 'regression':
889
- loss_fct = nn.MSELoss()
890
- if self.num_labels == 1:
891
- loss = loss_fct(logits.squeeze(), labels.squeeze())
892
- else:
893
- loss = loss_fct(logits, labels)
894
- elif self.config.problem_type == 'single_label_classification':
895
- loss_fct = nn.CrossEntropyLoss()
896
- loss = loss_fct(logits.view(-1, self.num_labels),
897
- labels.view(-1))
898
- elif self.config.problem_type == 'multi_label_classification':
899
- loss_fct = nn.BCEWithLogitsLoss()
900
- loss = loss_fct(logits, labels)
901
-
902
- if not return_dict:
903
- output = (logits,) + outputs[2:]
904
- return ((loss,) + output) if loss is not None else output
905
-
906
- return SequenceClassifierOutput(
907
- loss=loss,
908
- logits=logits,
909
- hidden_states=outputs[0],
910
- attentions=None,
911
- )
912
-
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
backbone/bert_padding.py DELETED
@@ -1,154 +0,0 @@
1
- # Copyright 2022 MosaicML Examples authors
2
- # SPDX-License-Identifier: Apache-2.0
3
-
4
- # Adapted from https://github.com/HazyResearch/flash-attention/blob/main/flash_attn/bert_padding.py
5
- # Which was adapted from https://github.com/mlcommons/training_results_v1.1/blob/main/NVIDIA/benchmarks/bert/implementations/pytorch/padding.py
6
-
7
-
8
- from typing import Tuple, cast
9
-
10
- import torch
11
- import torch.nn.functional as F
12
- from einops import rearrange, repeat
13
-
14
-
15
- class IndexFirstAxis(torch.autograd.Function):
16
-
17
- @staticmethod
18
- def forward(ctx, input: torch.Tensor,
19
- indices: torch.Tensor) -> torch.Tensor:
20
- """Get just the values of `input` which are at `indices`.
21
-
22
- Arguments:
23
- ctx: the autograd context object
24
- input: (b, ...) 2+ dimensional tensor
25
- indices: (num_idx) 1D tensor
26
- """
27
- ctx.save_for_backward(indices)
28
- assert input.ndim >= 2
29
- ctx.first_axis_dim, other_shape = input.shape[0], input.shape[
30
- 1:] # type: ignore
31
- second_dim = other_shape.numel(
32
- ) # product of sizes of all but first dimension
33
- # TD [2022-03-04] For some reason torch.gather is a bit faster than indexing.
34
- return torch.gather(
35
- rearrange(input, 'b ... -> b (...)'), # (b, ...) -> (b, second_dim)
36
- 0,
37
- repeat(indices, 'z -> z d',
38
- d=second_dim) # (indices,) -> (indices, second_dim)
39
- ).reshape(-1, *other_shape) # (num_idx, ...)
40
-
41
- @staticmethod
42
- def backward(ctx, grad_output: torch.Tensor) -> Tuple[torch.Tensor, None]:
43
- indices, = ctx.saved_tensors
44
- assert grad_output.ndim >= 2
45
- other_shape = grad_output.shape[1:]
46
- grad_output = rearrange(grad_output, 'b ... -> b (...)')
47
- grad_input = torch.zeros([ctx.first_axis_dim, grad_output.shape[1]],
48
- device=grad_output.device,
49
- dtype=grad_output.dtype)
50
- # TD [2022-03-04] For some reason torch.scatter is a bit faster than indexing.
51
- # grad_input[indices] = grad_output
52
- grad_input.scatter_(0,
53
- repeat(indices, 'z -> z d', d=grad_output.shape[1]),
54
- grad_output)
55
- return grad_input.reshape(ctx.first_axis_dim, *other_shape), None
56
-
57
-
58
- index_first_axis = IndexFirstAxis.apply
59
-
60
-
61
- class IndexPutFirstAxis(torch.autograd.Function):
62
-
63
- @staticmethod
64
- def forward(ctx, values: torch.Tensor, indices: torch.Tensor,
65
- first_axis_dim) -> torch.Tensor:
66
- ctx.save_for_backward(indices)
67
- assert indices.ndim == 1
68
- assert values.ndim >= 2
69
- output = torch.zeros(first_axis_dim,
70
- *values.shape[1:],
71
- device=values.device,
72
- dtype=values.dtype)
73
- output[indices] = values
74
- return output
75
-
76
- @staticmethod
77
- def backward(ctx,
78
- grad_output: torch.Tensor) -> Tuple[torch.Tensor, None, None]:
79
- indices, = ctx.saved_tensors
80
- grad_values = grad_output[indices]
81
- return grad_values, None, None
82
-
83
-
84
- index_put_first_axis = IndexPutFirstAxis.apply
85
-
86
-
87
- def unpad_input(
88
- hidden_states: torch.Tensor,
89
- attention_mask: torch.Tensor,
90
- ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor, int]:
91
- """Remove padding from input sequences.
92
-
93
- Arguments:
94
- hidden_states: (batch, seqlen, ...)
95
- attention_mask: (batch, seqlen), bool / int, 1 means valid and 0 means not valid.
96
-
97
- Returns:
98
- hidden_states: (total_nnz, ...), where total_nnz = number of tokens in selected in attention_mask.
99
- indices: (total_nnz)
100
- cu_seqlens: (batch + 1), the cumulative sequence lengths, used to index into hidden_states.
101
- max_seqlen_in_batch: int ()
102
- """
103
- seqlens_in_batch = attention_mask.sum(dim=-1, dtype=torch.int32)
104
- indices = torch.nonzero(attention_mask.flatten(), as_tuple=False).flatten()
105
- max_seqlen_in_batch = int(seqlens_in_batch.max().item())
106
- cu_seqlens = F.pad(torch.cumsum(seqlens_in_batch, dim=0, dtype=torch.int32),
107
- (1, 0))
108
- # TD [2022-03-04] We don't want to index with a bool mask, because Pytorch will expand the
109
- # bool mask, then call nonzero to get the indices, then index with those. The indices is @dim
110
- # times larger than it needs to be, wasting memory. It's faster and more memory-efficient to
111
- # index with integer indices. Moreover, torch's index is a bit slower than it needs to be,
112
- # so we write custom forward and backward to make it a bit faster.
113
- hidden_states = cast(
114
- torch.Tensor,
115
- index_first_axis(rearrange(hidden_states, 'b s ... -> (b s) ...'),
116
- indices))
117
- return hidden_states, indices, cu_seqlens, max_seqlen_in_batch
118
-
119
-
120
- def unpad_input_only(
121
- hidden_states: torch.Tensor,
122
- attention_mask: torch.Tensor,
123
- ) -> torch.Tensor:
124
- """Like unpad_input, but only return the unpadded first tensor.
125
-
126
- Save a small amount of overhead.
127
-
128
- Arguments:
129
- hidden_states: (batch, seqlen, ...)
130
- attention_mask: (batch, seqlen), bool / int, 1 means valid and 0 means not valid.
131
-
132
- Returns:
133
- hidden_states: (total_nnz, ...), where total_nnz = number of tokens in selected in attention_mask.
134
- """
135
- indices = torch.nonzero(attention_mask.flatten(), as_tuple=False).flatten()
136
- return index_first_axis(rearrange(hidden_states, 'b s ... -> (b s) ...'),
137
- indices)
138
-
139
-
140
- def pad_input(hidden_states: torch.Tensor, indices: torch.Tensor, batch: int,
141
- seqlen: int) -> torch.Tensor:
142
- """Add padding to sequences.
143
-
144
- Arguments:
145
- hidden_states: (total_nnz, ...), where total_nnz = number of tokens in selected in attention_mask.
146
- indices: (total_nnz)
147
- batch: int batch_size
148
- seqlen: int max sequence length
149
-
150
- Returns:
151
- hidden_states: (batch, seqlen, ...)
152
- """
153
- output = index_put_first_axis(hidden_states, indices, batch * seqlen)
154
- return rearrange(output, '(b s) ... -> b s ...', b=batch)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
backbone/config.json DELETED
@@ -1,76 +0,0 @@
1
- {
2
- "_name_or_path": "/data/lb/dnabert2/DNABERT_2-main/finetune/output/dnabert2/v1",
3
- "alibi_starting_size": 512,
4
- "architectures": [
5
- "BertForSequenceClassification"
6
- ],
7
- "attention_probs_dropout_prob": 0.0,
8
- "auto_map": {
9
- "AutoConfig": "configuration_bert.BertConfig",
10
- "AutoModel": "bert_layers.BertModel",
11
- "AutoModelForMaskedLM": "bert_layers.BertForMaskedLM",
12
- "AutoModelForSequenceClassification": "bert_layers.BertForSequenceClassification"
13
- },
14
- "classifier_dropout": null,
15
- "gradient_checkpointing": false,
16
- "hidden_act": "gelu",
17
- "hidden_dropout_prob": 0.1,
18
- "hidden_size": 768,
19
- "id2label": {
20
- "0": "LABEL_0",
21
- "1": "LABEL_1",
22
- "2": "LABEL_2",
23
- "3": "LABEL_3",
24
- "4": "LABEL_4",
25
- "5": "LABEL_5",
26
- "6": "LABEL_6",
27
- "7": "LABEL_7",
28
- "8": "LABEL_8",
29
- "9": "LABEL_9",
30
- "10": "LABEL_10",
31
- "11": "LABEL_11",
32
- "12": "LABEL_12",
33
- "13": "LABEL_13",
34
- "14": "LABEL_14",
35
- "15": "LABEL_15",
36
- "16": "LABEL_16",
37
- "17": "LABEL_17",
38
- "18": "LABEL_18",
39
- "19": "LABEL_19"
40
- },
41
- "initializer_range": 0.02,
42
- "intermediate_size": 3072,
43
- "label2id": {
44
- "LABEL_0": 0,
45
- "LABEL_1": 1,
46
- "LABEL_10": 10,
47
- "LABEL_11": 11,
48
- "LABEL_12": 12,
49
- "LABEL_13": 13,
50
- "LABEL_14": 14,
51
- "LABEL_15": 15,
52
- "LABEL_16": 16,
53
- "LABEL_17": 17,
54
- "LABEL_18": 18,
55
- "LABEL_19": 19,
56
- "LABEL_2": 2,
57
- "LABEL_3": 3,
58
- "LABEL_4": 4,
59
- "LABEL_5": 5,
60
- "LABEL_6": 6,
61
- "LABEL_7": 7,
62
- "LABEL_8": 8,
63
- "LABEL_9": 9
64
- },
65
- "layer_norm_eps": 1e-12,
66
- "max_position_embeddings": 512,
67
- "num_attention_heads": 12,
68
- "num_hidden_layers": 12,
69
- "position_embedding_type": "absolute",
70
- "problem_type": "single_label_classification",
71
- "torch_dtype": "float32",
72
- "transformers_version": "4.29.2",
73
- "type_vocab_size": 2,
74
- "use_cache": true,
75
- "vocab_size": 4096
76
- }
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
backbone/configuration_bert.py DELETED
@@ -1,26 +0,0 @@
1
- # Copyright 2022 MosaicML Examples authors
2
- # SPDX-License-Identifier: Apache-2.0
3
-
4
- from transformers.configuration_utils import PretrainedConfig
5
-
6
-
7
- class BertConfig(PretrainedConfig):
8
-
9
- def __init__(
10
- self,
11
- alibi_starting_size: int = 512,
12
- attention_probs_dropout_prob: float = 0.0,
13
- **kwargs,
14
- ):
15
- """Configuration class for MosaicBert.
16
-
17
- Args:
18
- alibi_starting_size (int): Use `alibi_starting_size` to determine how large of an alibi tensor to
19
- create when initializing the model. You should be able to ignore this parameter in most cases.
20
- Defaults to 512.
21
- attention_probs_dropout_prob (float): By default, turn off attention dropout in Mosaic BERT
22
- (otherwise, Flash Attention will be off by default). Defaults to 0.0.
23
- """
24
- super().__init__(
25
- attention_probs_dropout_prob=attention_probs_dropout_prob, **kwargs)
26
- self.alibi_starting_size = alibi_starting_size
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
backbone/flash_attn_triton.py DELETED
@@ -1,1112 +0,0 @@
1
- # Copyright 2022 MosaicML Examples authors
2
- # SPDX-License-Identifier: Apache-2.0
3
-
4
- """Triton implementation of Flash Attention.
5
-
6
- # Copyright (c) 2022, Tri Dao.
7
- #
8
- # Licensed under the Apache License, Version 2.0 (the "License");
9
- # you may not use this file except in compliance with the License.
10
- # You may obtain a copy of the License at
11
- #
12
- # http://www.apache.org/licenses/LICENSE-2.0
13
- #
14
- # Unless required by applicable law or agreed to in writing, software
15
- # distributed under the License is distributed on an "AS IS" BASIS,
16
- # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17
- # See the License for the specific language governing permissions and
18
- # limitations under the License.
19
-
20
- *Experimental* implementation of FlashAttention in Triton.
21
- We use the FlashAttention implementation from Phil Tillet a starting point.
22
- https://github.com/openai/triton/blob/master/python/tutorials/06-fused-attention.py
23
-
24
- Changes:
25
- - Implement both causal and non-causal attention.
26
- - Implement both self-attention and cross-attention.
27
- - Support arbitrary seqlens (not just multiples of 128), for both forward and backward.
28
- - Support all head dimensions up to 128 (not just 16, 32, 64, 128), for both forward and backward.
29
- - Support attention bias.
30
- - Speed up the forward pass a bit, and only store the LSE instead of m and l.
31
- - Make the backward for d=128 much faster by reducing register spilling.
32
- - Optionally parallelize the backward pass across seqlen_k, to deal with the case of
33
- small batch size * nheads.
34
-
35
- Caution:
36
- - If you plan to use headdim other than 64 and 128, you should test for race conditions
37
- (due to the Triton compiler), as done in tests/test_flash_attn.py
38
- "test_flash_attn_triton_race_condition". I've tested and fixed many race conditions
39
- for different head dimensions (40, 48, 64, 128, 80, 88, 96), but I'm still not 100% confident
40
- that there are none left for other head dimensions.
41
- Differences between this Triton version and the CUDA version:
42
- - Triton version doesn't support dropout.
43
- - Triton forward is generally faster than CUDA forward.
44
- - Triton backward is faster than CUDA backward when batch * nheads is small, and when headdim=64.
45
- It is slightly slower when headdim=128 and batch * nheads is large.
46
- - Triton version doesn't yet support different sequence lengths in a batch (i.e., RaggedTensor/NestedTensor).
47
- """
48
-
49
- import math
50
-
51
- import torch
52
- import triton # type: ignore (reportMissingImports)
53
- import triton.language as tl # type: ignore (reportMissingImports)
54
- from einops import repeat
55
-
56
-
57
- @triton.autotune(
58
- configs=[
59
- triton.Config({
60
- 'BLOCK_M': 128,
61
- 'BLOCK_N': 128
62
- },
63
- num_warps=8,
64
- num_stages=1),
65
- # This config has a race condition when EVEN_M == False, disabling it for now.
66
- # triton.Config({"BLOCK_M": 64, "BLOCK_N": 64}, num_warps=4, num_stages=1),
67
- ],
68
- key=[
69
- 'CACHE_KEY_SEQLEN_Q', 'CACHE_KEY_SEQLEN_K', 'BIAS_TYPE', 'IS_CAUSAL',
70
- 'BLOCK_HEADDIM'
71
- ])
72
- @triton.heuristics({
73
- 'EVEN_M': lambda args: args['seqlen_q'] % args['BLOCK_M'] == 0,
74
- 'EVEN_N': lambda args: args['seqlen_k'] % args['BLOCK_N'] == 0,
75
- 'EVEN_HEADDIM': lambda args: args['headdim'] == args['BLOCK_HEADDIM'],
76
- })
77
- @triton.jit
78
- def _fwd_kernel(
79
- Q,
80
- K,
81
- V,
82
- Bias,
83
- Out,
84
- Lse,
85
- TMP, # NOTE: TMP is a scratchpad buffer to workaround a compiler bug
86
- softmax_scale,
87
- stride_qb,
88
- stride_qh,
89
- stride_qm,
90
- stride_kb,
91
- stride_kh,
92
- stride_kn,
93
- stride_vb,
94
- stride_vh,
95
- stride_vn,
96
- stride_bb,
97
- stride_bh,
98
- stride_bm,
99
- stride_ob,
100
- stride_oh,
101
- stride_om,
102
- nheads,
103
- seqlen_q,
104
- seqlen_k,
105
- seqlen_q_rounded,
106
- headdim,
107
- CACHE_KEY_SEQLEN_Q,
108
- CACHE_KEY_SEQLEN_K,
109
- BIAS_TYPE: tl.constexpr,
110
- IS_CAUSAL: tl.constexpr,
111
- BLOCK_HEADDIM: tl.constexpr,
112
- EVEN_M: tl.constexpr,
113
- EVEN_N: tl.constexpr,
114
- EVEN_HEADDIM: tl.constexpr,
115
- BLOCK_M: tl.constexpr,
116
- BLOCK_N: tl.constexpr,
117
- ):
118
- start_m = tl.program_id(0)
119
- off_hb = tl.program_id(1)
120
- off_b = off_hb // nheads
121
- off_h = off_hb % nheads
122
- # off_b = tl.program_id(1)
123
- # off_h = tl.program_id(2)
124
- # off_hb = off_b * nheads + off_h
125
- # initialize offsets
126
- offs_m = start_m * BLOCK_M + tl.arange(0, BLOCK_M)
127
- offs_n = tl.arange(0, BLOCK_N)
128
- offs_d = tl.arange(0, BLOCK_HEADDIM)
129
- # Initialize pointers to Q, K, V
130
- # Adding parenthesis around indexing might use int32 math instead of int64 math?
131
- # https://github.com/openai/triton/issues/741
132
- # I'm seeing a tiny bit of difference (5-7us)
133
- q_ptrs = Q + off_b * stride_qb + off_h * stride_qh + (
134
- offs_m[:, None] * stride_qm + offs_d[None, :])
135
- k_ptrs = K + off_b * stride_kb + off_h * stride_kh + (
136
- offs_n[:, None] * stride_kn + offs_d[None, :])
137
- v_ptrs = V + off_b * stride_vb + off_h * stride_vh + (
138
- offs_n[:, None] * stride_vn + offs_d[None, :])
139
- if BIAS_TYPE == 'vector':
140
- b_ptrs = Bias + off_b * stride_bb + off_h * stride_bh + offs_n
141
- elif BIAS_TYPE == 'matrix':
142
- b_ptrs = Bias + off_b * stride_bb + off_h * stride_bh + (
143
- offs_m[:, None] * stride_bm + offs_n[None, :])
144
- else:
145
- raise ValueError("BIAS_TYPE must be one of {'vector', 'matrix'}")
146
- # initialize pointer to m and l
147
- t_ptrs = TMP + off_hb * seqlen_q_rounded + offs_m
148
- lse_i = tl.zeros([BLOCK_M], dtype=tl.float32) - float('inf')
149
- m_i = tl.zeros([BLOCK_M], dtype=tl.float32) - float('inf')
150
- acc_o = tl.zeros([BLOCK_M, BLOCK_HEADDIM], dtype=tl.float32)
151
- # load q: it will stay in SRAM throughout
152
- # [2022-10-30] TD: Triton bug - in the case of EVEN_M=True and EVEN_N=False, if we just call
153
- # tl.load(q_ptrs), we get the wrong output!
154
- if EVEN_M & EVEN_N:
155
- if EVEN_HEADDIM:
156
- q = tl.load(q_ptrs)
157
- else:
158
- q = tl.load(q_ptrs, mask=offs_d[None, :] < headdim, other=0.0)
159
- else:
160
- if EVEN_HEADDIM:
161
- q = tl.load(q_ptrs, mask=offs_m[:, None] < seqlen_q, other=0.0)
162
- else:
163
- q = tl.load(q_ptrs,
164
- mask=(offs_m[:, None] < seqlen_q) &
165
- (offs_d[None, :] < headdim),
166
- other=0.0)
167
- # loop over k, v and update accumulator
168
- end_n = seqlen_k if not IS_CAUSAL else tl.minimum(
169
- (start_m + 1) * BLOCK_M, seqlen_k)
170
- for start_n in range(0, end_n, BLOCK_N):
171
- start_n = tl.multiple_of(start_n, BLOCK_N)
172
- # -- compute qk ----
173
- if EVEN_N & EVEN_M: # If we just do "if EVEN_N", there seems to be some race condition
174
- if EVEN_HEADDIM:
175
- k = tl.load(k_ptrs + start_n * stride_kn)
176
- else:
177
- k = tl.load(k_ptrs + start_n * stride_kn,
178
- mask=offs_d[None, :] < headdim,
179
- other=0.0)
180
- else:
181
- if EVEN_HEADDIM:
182
- k = tl.load(k_ptrs + start_n * stride_kn,
183
- mask=(start_n + offs_n)[:, None] < seqlen_k,
184
- other=0.0)
185
- else:
186
- k = tl.load(k_ptrs + start_n * stride_kn,
187
- mask=((start_n + offs_n)[:, None] < seqlen_k) &
188
- (offs_d[None, :] < headdim),
189
- other=0.0)
190
- qk = tl.zeros([BLOCK_M, BLOCK_N], dtype=tl.float32)
191
- qk += tl.dot(q, k, trans_b=True)
192
- # Trying to combine the two masks seem to make the result wrong
193
- if not EVEN_N: # Need to mask out otherwise the softmax is wrong
194
- qk += tl.where((start_n + offs_n)[None, :] < seqlen_k, 0,
195
- float('-inf'))
196
- if IS_CAUSAL:
197
- qk += tl.where(offs_m[:, None] >= (start_n + offs_n)[None, :], 0,
198
- float('-inf'))
199
- if BIAS_TYPE != 'none':
200
- if BIAS_TYPE == 'vector':
201
- if EVEN_N:
202
- bias = tl.load(b_ptrs + start_n).to(tl.float32)
203
- else:
204
- bias = tl.load(b_ptrs + start_n,
205
- mask=(start_n + offs_n) < seqlen_k,
206
- other=0.0).to(tl.float32)
207
- bias = bias[None, :]
208
- elif BIAS_TYPE == 'matrix':
209
- if EVEN_M & EVEN_N:
210
- bias = tl.load(b_ptrs + start_n).to(tl.float32)
211
- else:
212
- bias = tl.load(b_ptrs + start_n,
213
- mask=(offs_m[:, None] < seqlen_q) &
214
- ((start_n + offs_n)[None, :] < seqlen_k),
215
- other=0.0).to(tl.float32)
216
- else:
217
- raise ValueError(
218
- "BIAS_TYPE must be one of {'vector', 'matrix'}")
219
- # Slightly faster to multiply the softmax_scale in the tl.exp below since the compiler
220
- # can then fuse the mult and add into an fma instruction. But if we have bias we need to
221
- # to multiply with softmax_scale here.
222
- qk = qk * softmax_scale + bias
223
- m_ij = tl.maximum(tl.max(qk, 1), lse_i)
224
- p = tl.exp(qk - m_ij[:, None])
225
- else:
226
- m_ij = tl.maximum(tl.max(qk, 1) * softmax_scale, lse_i)
227
- p = tl.exp(qk * softmax_scale - m_ij[:, None])
228
- l_ij = tl.sum(p, 1)
229
-
230
- # scale acc_o
231
- acc_o_scale = tl.exp(m_i - m_ij)
232
-
233
- # # -- update output accumulator --
234
- # BUG: have to store and immediately load
235
- tl.store(t_ptrs, acc_o_scale)
236
- acc_o_scale = tl.load(t_ptrs)
237
- acc_o = acc_o * acc_o_scale[:, None]
238
- # update acc_o
239
- if EVEN_N & EVEN_M: # If we just do "if EVEN_N", there seems to be some race condition
240
- if EVEN_HEADDIM:
241
- v = tl.load(v_ptrs + start_n * stride_vn)
242
- else:
243
- v = tl.load(v_ptrs + start_n * stride_vn,
244
- mask=offs_d[None, :] < headdim,
245
- other=0.0)
246
- else:
247
- if EVEN_HEADDIM:
248
- v = tl.load(v_ptrs + start_n * stride_vn,
249
- mask=(start_n + offs_n)[:, None] < seqlen_k,
250
- other=0.0)
251
- else:
252
- v = tl.load(v_ptrs + start_n * stride_vn,
253
- mask=((start_n + offs_n)[:, None] < seqlen_k) &
254
- (offs_d[None, :] < headdim),
255
- other=0.0)
256
- p = p.to(v.dtype)
257
- acc_o += tl.dot(p, v)
258
-
259
- # -- update statistics
260
- m_i = m_ij
261
- l_i_new = tl.exp(lse_i - m_ij) + l_ij
262
- lse_i = m_ij + tl.log(l_i_new)
263
-
264
- o_scale = tl.exp(m_i - lse_i)
265
- # BUG: have to store and immediately load
266
- tl.store(t_ptrs, o_scale)
267
- o_scale = tl.load(t_ptrs)
268
- acc_o = acc_o * o_scale[:, None]
269
- # rematerialize offsets to save registers
270
- start_m = tl.program_id(0)
271
- offs_m = start_m * BLOCK_M + tl.arange(0, BLOCK_M)
272
- # write back l and m
273
- lse_ptrs = Lse + off_hb * seqlen_q_rounded + offs_m
274
- tl.store(lse_ptrs, lse_i)
275
- # initialize pointers to output
276
- offs_n = tl.arange(0, BLOCK_HEADDIM)
277
- out_ptrs = Out + off_b * stride_ob + off_h * stride_oh + (
278
- offs_m[:, None] * stride_om + offs_n[None, :])
279
- if EVEN_M:
280
- if EVEN_HEADDIM:
281
- tl.store(out_ptrs, acc_o)
282
- else:
283
- tl.store(out_ptrs, acc_o, mask=offs_d[None, :] < headdim)
284
- else:
285
- if EVEN_HEADDIM:
286
- tl.store(out_ptrs, acc_o, mask=offs_m[:, None] < seqlen_q)
287
- else:
288
- tl.store(out_ptrs,
289
- acc_o,
290
- mask=(offs_m[:, None] < seqlen_q) &
291
- (offs_d[None, :] < headdim))
292
-
293
-
294
- @triton.jit
295
- def _bwd_preprocess_do_o_dot(
296
- Out,
297
- DO,
298
- Delta,
299
- stride_ob,
300
- stride_oh,
301
- stride_om,
302
- stride_dob,
303
- stride_doh,
304
- stride_dom,
305
- nheads,
306
- seqlen_q,
307
- seqlen_q_rounded,
308
- headdim,
309
- BLOCK_M: tl.constexpr,
310
- BLOCK_HEADDIM: tl.constexpr,
311
- ):
312
- start_m = tl.program_id(0)
313
- off_hb = tl.program_id(1)
314
- off_b = off_hb // nheads
315
- off_h = off_hb % nheads
316
- # initialize offsets
317
- offs_m = start_m * BLOCK_M + tl.arange(0, BLOCK_M)
318
- offs_d = tl.arange(0, BLOCK_HEADDIM)
319
- # load
320
- o = tl.load(Out + off_b * stride_ob + off_h * stride_oh +
321
- offs_m[:, None] * stride_om + offs_d[None, :],
322
- mask=(offs_m[:, None] < seqlen_q) & (offs_d[None, :] < headdim),
323
- other=0.0).to(tl.float32)
324
- do = tl.load(DO + off_b * stride_dob + off_h * stride_doh +
325
- offs_m[:, None] * stride_dom + offs_d[None, :],
326
- mask=(offs_m[:, None] < seqlen_q) &
327
- (offs_d[None, :] < headdim),
328
- other=0.0).to(tl.float32)
329
- delta = tl.sum(o * do, axis=1)
330
- # write-back
331
- tl.store(Delta + off_hb * seqlen_q_rounded + offs_m, delta)
332
-
333
-
334
- @triton.jit
335
- def _bwd_kernel_one_col_block(
336
- start_n,
337
- Q,
338
- K,
339
- V,
340
- Bias,
341
- DO,
342
- DQ,
343
- DK,
344
- DV,
345
- LSE,
346
- D,
347
- softmax_scale,
348
- stride_qm,
349
- stride_kn,
350
- stride_vn,
351
- stride_bm,
352
- stride_dom,
353
- stride_dqm,
354
- stride_dkn,
355
- stride_dvn,
356
- seqlen_q,
357
- seqlen_k,
358
- headdim,
359
- ATOMIC_ADD: tl.constexpr,
360
- BIAS_TYPE: tl.constexpr,
361
- IS_CAUSAL: tl.constexpr,
362
- BLOCK_HEADDIM: tl.constexpr,
363
- EVEN_M: tl.constexpr,
364
- EVEN_N: tl.constexpr,
365
- EVEN_HEADDIM: tl.constexpr,
366
- BLOCK_M: tl.constexpr,
367
- BLOCK_N: tl.constexpr,
368
- ):
369
- # We need to make sure begin_m is a multiple of BLOCK_M (not BLOCK_N)
370
- begin_m = 0 if not IS_CAUSAL else ((start_n * BLOCK_N) // BLOCK_M) * BLOCK_M
371
- # initialize row/col offsets
372
- offs_qm = begin_m + tl.arange(0, BLOCK_M)
373
- offs_n = start_n * BLOCK_N + tl.arange(0, BLOCK_N)
374
- offs_m = tl.arange(0, BLOCK_M)
375
- offs_d = tl.arange(0, BLOCK_HEADDIM)
376
- # initialize pointers to value-like data
377
- q_ptrs = Q + (offs_qm[:, None] * stride_qm + offs_d[None, :])
378
- k_ptrs = K + (offs_n[:, None] * stride_kn + offs_d[None, :])
379
- v_ptrs = V + (offs_n[:, None] * stride_vn + offs_d[None, :])
380
- do_ptrs = DO + (offs_qm[:, None] * stride_dom + offs_d[None, :])
381
- dq_ptrs = DQ + (offs_qm[:, None] * stride_dqm + offs_d[None, :])
382
- if BIAS_TYPE == 'vector':
383
- b_ptrs = Bias + offs_n
384
- elif BIAS_TYPE == 'matrix':
385
- b_ptrs = Bias + (offs_qm[:, None] * stride_bm + offs_n[None, :])
386
- else:
387
- raise ValueError("BIAS_TYPE must be one of {'vector', 'matrix'}")
388
- # initialize dv and dk
389
- dv = tl.zeros([BLOCK_N, BLOCK_HEADDIM], dtype=tl.float32)
390
- dk = tl.zeros([BLOCK_N, BLOCK_HEADDIM], dtype=tl.float32)
391
- # k and v stay in SRAM throughout
392
- # [2022-10-30] TD: Same bug as the fwd. In the case of EVEN_N=True and EVEN_M=False,
393
- # if we just call tl.load(k_ptrs), we get the wrong output!
394
- if EVEN_N & EVEN_M:
395
- if EVEN_HEADDIM:
396
- k = tl.load(k_ptrs)
397
- v = tl.load(v_ptrs)
398
- else:
399
- k = tl.load(k_ptrs, mask=offs_d[None, :] < headdim, other=0.0)
400
- v = tl.load(v_ptrs, mask=offs_d[None, :] < headdim, other=0.0)
401
- else:
402
- if EVEN_HEADDIM:
403
- k = tl.load(k_ptrs, mask=offs_n[:, None] < seqlen_k, other=0.0)
404
- v = tl.load(v_ptrs, mask=offs_n[:, None] < seqlen_k, other=0.0)
405
- else:
406
- k = tl.load(k_ptrs,
407
- mask=(offs_n[:, None] < seqlen_k) &
408
- (offs_d[None, :] < headdim),
409
- other=0.0)
410
- v = tl.load(v_ptrs,
411
- mask=(offs_n[:, None] < seqlen_k) &
412
- (offs_d[None, :] < headdim),
413
- other=0.0)
414
- # loop over rows
415
- num_block_m = tl.cdiv(seqlen_q, BLOCK_M)
416
- for start_m in range(begin_m, num_block_m * BLOCK_M, BLOCK_M):
417
- start_m = tl.multiple_of(start_m, BLOCK_M)
418
- offs_m_curr = start_m + offs_m
419
- # load q, k, v, do on-chip
420
- # Same bug as below. Otherwise gives wrong result for headdim=40, seqlen=(128, 117)
421
- if EVEN_M & EVEN_HEADDIM:
422
- q = tl.load(q_ptrs)
423
- else:
424
- if EVEN_HEADDIM:
425
- q = tl.load(q_ptrs,
426
- mask=offs_m_curr[:, None] < seqlen_q,
427
- other=0.0)
428
- else:
429
- q = tl.load(q_ptrs,
430
- mask=(offs_m_curr[:, None] < seqlen_q) &
431
- (offs_d[None, :] < headdim),
432
- other=0.0)
433
- # recompute p = softmax(qk, dim=-1).T
434
- qk = tl.dot(q, k, trans_b=True)
435
- # Trying to combine the two masks seem to make the result wrong
436
- if not EVEN_N: # Need to mask out otherwise the softmax is wrong
437
- qk = tl.where(offs_n[None, :] < seqlen_k, qk, float('-inf'))
438
- if IS_CAUSAL:
439
- qk = tl.where(offs_m_curr[:, None] >= (offs_n[None, :]), qk,
440
- float('-inf'))
441
- if BIAS_TYPE != 'none':
442
- if BIAS_TYPE == 'vector':
443
- if EVEN_N:
444
- bias = tl.load(b_ptrs).to(tl.float32)
445
- else:
446
- bias = tl.load(b_ptrs, mask=offs_n < seqlen_k,
447
- other=0.0).to(tl.float32)
448
- bias = bias[None, :]
449
- elif BIAS_TYPE == 'matrix':
450
- if EVEN_M & EVEN_N:
451
- bias = tl.load(b_ptrs).to(tl.float32)
452
- else:
453
- bias = tl.load(b_ptrs,
454
- mask=(offs_m_curr[:, None] < seqlen_q) &
455
- (offs_n[None, :] < seqlen_k),
456
- other=0.0).to(tl.float32)
457
- else:
458
- raise ValueError(
459
- "BIAS_TYPE must be one of {'vector', 'matrix'}")
460
- qk = qk * softmax_scale + bias
461
- # There seems to be a race condition when headdim=48/96, and dq, dk, dv are wrong.
462
- # Also wrong for headdim=64.
463
- if not (EVEN_M & EVEN_HEADDIM):
464
- tl.debug_barrier()
465
- lse_i = tl.load(LSE + offs_m_curr)
466
- if BIAS_TYPE == 'none':
467
- p = tl.exp(qk * softmax_scale - lse_i[:, None])
468
- else:
469
- p = tl.exp(qk - lse_i[:, None])
470
- # compute dv
471
- # [2022-10-30] TD: A Triton bug: if EVEN_M=True and EVEN_HEADDIM=False, if we call
472
- # do = tl.load(do_ptrs, mask=offs_d[None, :] < headdim, other=0.0), we get wrong outputs
473
- # in the case of headdim=48/96, seqlen_q & seqlen_k >= 512. If headdim=40 or seqlen < 512,
474
- # the output is correct.
475
- if EVEN_M & EVEN_HEADDIM:
476
- do = tl.load(do_ptrs)
477
- else:
478
- # [2022-11-01] TD: Triton bug, there's a race condition if we just use m_mask and not d_mask.
479
- do = tl.load(do_ptrs,
480
- mask=(offs_m_curr[:, None] < seqlen_q) &
481
- (offs_d[None, :] < headdim),
482
- other=0.0)
483
- # if EVEN_M:
484
- # if EVEN_HEADDIM:
485
- # do = tl.load(do_ptrs)
486
- # else:
487
- # do = tl.load(do_ptrs, mask=offs_d[None, :] < headdim, other=0.0)
488
- # else:
489
- # if EVEN_HEADDIM:
490
- # do = tl.load(do_ptrs, mask=offs_m_curr[:, None] < seqlen_q, other=0.0)
491
- # else:
492
- # do = tl.load(do_ptrs, mask=(offs_m_curr[:, None] < seqlen_q)
493
- # & (offs_d[None, :] < headdim), other=0.0)
494
- dv += tl.dot(p.to(do.dtype), do, trans_a=True)
495
- # compute dp = dot(v, do)
496
- # There seems to be a race condition when headdim=48/96, and dq, dk are wrong.
497
- # Also wrong for headdim=128, seqlen=(108, 256), and ATOMIC_ADD=True
498
- # Also wrong for headdim=64, seqlen=(1023, 1024), and ATOMIC_ADD=False
499
- if not (EVEN_M & EVEN_HEADDIM):
500
- tl.debug_barrier()
501
- dp = tl.dot(do, v, trans_b=True)
502
- # There's a race condition for headdim=48
503
- if not EVEN_HEADDIM:
504
- tl.debug_barrier()
505
- # compute ds = p * (dp - delta[:, None])
506
- # Putting the subtraction after the dp matmul (instead of before) is slightly faster
507
- Di = tl.load(D + offs_m_curr)
508
- # Converting ds to q.dtype here reduces register pressure and makes it much faster
509
- # for BLOCK_HEADDIM=128
510
- ds = (p * (dp - Di[:, None]) * softmax_scale).to(q.dtype)
511
- # compute dk = dot(ds.T, q)
512
- dk += tl.dot(ds, q, trans_a=True)
513
- # compute dq
514
- if not ATOMIC_ADD:
515
- if EVEN_M & EVEN_HEADDIM: # Race condition if we just do EVEN_M
516
- dq = tl.load(dq_ptrs, eviction_policy='evict_last')
517
- dq += tl.dot(ds, k)
518
- tl.store(dq_ptrs, dq, eviction_policy='evict_last')
519
- else:
520
- if EVEN_HEADDIM:
521
- dq = tl.load(dq_ptrs,
522
- mask=offs_m_curr[:, None] < seqlen_q,
523
- other=0.0,
524
- eviction_policy='evict_last')
525
- dq += tl.dot(ds, k)
526
- tl.store(dq_ptrs,
527
- dq,
528
- mask=offs_m_curr[:, None] < seqlen_q,
529
- eviction_policy='evict_last')
530
- else:
531
- dq = tl.load(dq_ptrs,
532
- mask=(offs_m_curr[:, None] < seqlen_q) &
533
- (offs_d[None, :] < headdim),
534
- other=0.0,
535
- eviction_policy='evict_last')
536
- dq += tl.dot(ds, k)
537
- tl.store(dq_ptrs,
538
- dq,
539
- mask=(offs_m_curr[:, None] < seqlen_q) &
540
- (offs_d[None, :] < headdim),
541
- eviction_policy='evict_last')
542
- else: # If we're parallelizing across the seqlen_k dimension
543
- dq = tl.dot(ds, k)
544
- if EVEN_M & EVEN_HEADDIM: # Race condition if we just do EVEN_M
545
- tl.atomic_add(dq_ptrs, dq)
546
- else:
547
- if EVEN_HEADDIM:
548
- tl.atomic_add(dq_ptrs,
549
- dq,
550
- mask=offs_m_curr[:, None] < seqlen_q)
551
- else:
552
- tl.atomic_add(dq_ptrs,
553
- dq,
554
- mask=(offs_m_curr[:, None] < seqlen_q) &
555
- (offs_d[None, :] < headdim))
556
- # increment pointers
557
- dq_ptrs += BLOCK_M * stride_dqm
558
- q_ptrs += BLOCK_M * stride_qm
559
- do_ptrs += BLOCK_M * stride_dom
560
- if BIAS_TYPE == 'matrix':
561
- b_ptrs += BLOCK_M * stride_bm
562
- # write-back
563
- dv_ptrs = DV + (offs_n[:, None] * stride_dvn + offs_d[None, :])
564
- dk_ptrs = DK + (offs_n[:, None] * stride_dkn + offs_d[None, :])
565
- # [2022-11-01] TD: Same bug. In the case of EVEN_N=True and EVEN_M=False,
566
- # if we just call tl.store(dv_ptrs), there's a race condition
567
- if EVEN_N & EVEN_M:
568
- if EVEN_HEADDIM:
569
- tl.store(dv_ptrs, dv)
570
- tl.store(dk_ptrs, dk)
571
- else:
572
- tl.store(dv_ptrs, dv, mask=offs_d[None, :] < headdim)
573
- tl.store(dk_ptrs, dk, mask=offs_d[None, :] < headdim)
574
- else:
575
- if EVEN_HEADDIM:
576
- tl.store(dv_ptrs, dv, mask=offs_n[:, None] < seqlen_k)
577
- tl.store(dk_ptrs, dk, mask=offs_n[:, None] < seqlen_k)
578
- else:
579
- tl.store(dv_ptrs,
580
- dv,
581
- mask=(offs_n[:, None] < seqlen_k) &
582
- (offs_d[None, :] < headdim))
583
- tl.store(dk_ptrs,
584
- dk,
585
- mask=(offs_n[:, None] < seqlen_k) &
586
- (offs_d[None, :] < headdim))
587
-
588
-
589
- def init_to_zero(name):
590
- return lambda nargs: nargs[name].zero_()
591
-
592
-
593
- @triton.autotune(
594
- configs=[
595
- triton.Config(
596
- {
597
- 'BLOCK_M': 128,
598
- 'BLOCK_N': 128,
599
- 'SEQUENCE_PARALLEL': False
600
- },
601
- num_warps=8,
602
- num_stages=1,
603
- pre_hook=init_to_zero('DQ')),
604
- triton.Config(
605
- {
606
- 'BLOCK_M': 128,
607
- 'BLOCK_N': 128,
608
- 'SEQUENCE_PARALLEL': True
609
- },
610
- num_warps=8,
611
- num_stages=1,
612
- pre_hook=init_to_zero('DQ')),
613
- # Other configs seem to give wrong results when seqlen_q % 128 != 0, disabling them for now
614
- # # Kernel is buggy (give wrong result) if we set BLOCK_m=128, BLOCK_n=64, num_warps=*4*
615
- # triton.Config({"BLOCK_M": 128, "BLOCK_N": 64, "SEQUENCE_PARALLEL": False}, num_warps=8, num_stages=1, pre_hook=init_to_zero('DQ')),
616
- # triton.Config({"BLOCK_M": 128, "BLOCK_N": 64, "SEQUENCE_PARALLEL": True}, num_warps=8, num_stages=1, pre_hook=init_to_zero('DQ')),
617
- # triton.Config({"BLOCK_M": 64, "BLOCK_N": 64, "SEQUENCE_PARALLEL": False}, num_warps=4, num_stages=1, pre_hook=init_to_zero('DQ')),
618
- # triton.Config({"BLOCK_M": 64, "BLOCK_N": 64, "SEQUENCE_PARALLEL": True}, num_warps=4, num_stages=1, pre_hook=init_to_zero('DQ')),
619
- ],
620
- key=[
621
- 'CACHE_KEY_SEQLEN_Q', 'CACHE_KEY_SEQLEN_K', 'BIAS_TYPE', 'IS_CAUSAL',
622
- 'BLOCK_HEADDIM'
623
- ],
624
- )
625
- @triton.heuristics({
626
- 'EVEN_M': lambda args: args['seqlen_q'] % args['BLOCK_M'] == 0,
627
- 'EVEN_N': lambda args: args['seqlen_k'] % args['BLOCK_N'] == 0,
628
- 'EVEN_HEADDIM': lambda args: args['headdim'] == args['BLOCK_HEADDIM'],
629
- })
630
- @triton.jit
631
- def _bwd_kernel(
632
- Q,
633
- K,
634
- V,
635
- Bias,
636
- DO,
637
- DQ,
638
- DK,
639
- DV,
640
- LSE,
641
- D,
642
- softmax_scale,
643
- stride_qb,
644
- stride_qh,
645
- stride_qm,
646
- stride_kb,
647
- stride_kh,
648
- stride_kn,
649
- stride_vb,
650
- stride_vh,
651
- stride_vn,
652
- stride_bb,
653
- stride_bh,
654
- stride_bm,
655
- stride_dob,
656
- stride_doh,
657
- stride_dom,
658
- stride_dqb,
659
- stride_dqh,
660
- stride_dqm,
661
- stride_dkb,
662
- stride_dkh,
663
- stride_dkn,
664
- stride_dvb,
665
- stride_dvh,
666
- stride_dvn,
667
- nheads,
668
- seqlen_q,
669
- seqlen_k,
670
- seqlen_q_rounded,
671
- headdim,
672
- CACHE_KEY_SEQLEN_Q,
673
- CACHE_KEY_SEQLEN_K,
674
- BIAS_TYPE: tl.constexpr,
675
- IS_CAUSAL: tl.constexpr,
676
- BLOCK_HEADDIM: tl.constexpr,
677
- SEQUENCE_PARALLEL: tl.constexpr,
678
- EVEN_M: tl.constexpr,
679
- EVEN_N: tl.constexpr,
680
- EVEN_HEADDIM: tl.constexpr,
681
- BLOCK_M: tl.constexpr,
682
- BLOCK_N: tl.constexpr,
683
- ):
684
- off_hb = tl.program_id(1)
685
- off_b = off_hb // nheads
686
- off_h = off_hb % nheads
687
- # offset pointers for batch/head
688
- Q += off_b * stride_qb + off_h * stride_qh
689
- K += off_b * stride_kb + off_h * stride_kh
690
- V += off_b * stride_vb + off_h * stride_vh
691
- DO += off_b * stride_dob + off_h * stride_doh
692
- DQ += off_b * stride_dqb + off_h * stride_dqh
693
- DK += off_b * stride_dkb + off_h * stride_dkh
694
- DV += off_b * stride_dvb + off_h * stride_dvh
695
- if BIAS_TYPE != 'none':
696
- Bias += off_b * stride_bb + off_h * stride_bh
697
- # pointer to row-wise quantities in value-like data
698
- D += off_hb * seqlen_q_rounded
699
- LSE += off_hb * seqlen_q_rounded
700
- if not SEQUENCE_PARALLEL:
701
- num_block_n = tl.cdiv(seqlen_k, BLOCK_N)
702
- for start_n in range(0, num_block_n):
703
- _bwd_kernel_one_col_block(start_n,
704
- Q,
705
- K,
706
- V,
707
- Bias,
708
- DO,
709
- DQ,
710
- DK,
711
- DV,
712
- LSE,
713
- D,
714
- softmax_scale,
715
- stride_qm,
716
- stride_kn,
717
- stride_vn,
718
- stride_bm,
719
- stride_dom,
720
- stride_dqm,
721
- stride_dkn,
722
- stride_dvn,
723
- seqlen_q,
724
- seqlen_k,
725
- headdim,
726
- ATOMIC_ADD=False,
727
- BIAS_TYPE=BIAS_TYPE,
728
- IS_CAUSAL=IS_CAUSAL,
729
- BLOCK_HEADDIM=BLOCK_HEADDIM,
730
- EVEN_M=EVEN_M,
731
- EVEN_N=EVEN_N,
732
- EVEN_HEADDIM=EVEN_HEADDIM,
733
- BLOCK_M=BLOCK_M,
734
- BLOCK_N=BLOCK_N)
735
- else:
736
- start_n = tl.program_id(0)
737
- _bwd_kernel_one_col_block(start_n,
738
- Q,
739
- K,
740
- V,
741
- Bias,
742
- DO,
743
- DQ,
744
- DK,
745
- DV,
746
- LSE,
747
- D,
748
- softmax_scale,
749
- stride_qm,
750
- stride_kn,
751
- stride_vn,
752
- stride_bm,
753
- stride_dom,
754
- stride_dqm,
755
- stride_dkn,
756
- stride_dvn,
757
- seqlen_q,
758
- seqlen_k,
759
- headdim,
760
- ATOMIC_ADD=True,
761
- BIAS_TYPE=BIAS_TYPE,
762
- IS_CAUSAL=IS_CAUSAL,
763
- BLOCK_HEADDIM=BLOCK_HEADDIM,
764
- EVEN_M=EVEN_M,
765
- EVEN_N=EVEN_N,
766
- EVEN_HEADDIM=EVEN_HEADDIM,
767
- BLOCK_M=BLOCK_M,
768
- BLOCK_N=BLOCK_N)
769
-
770
-
771
- def _flash_attn_forward(q, k, v, bias=None, causal=False, softmax_scale=None):
772
- # shape constraints
773
- batch, seqlen_q, nheads, d = q.shape
774
- _, seqlen_k, _, _ = k.shape
775
- assert k.shape == (batch, seqlen_k, nheads, d)
776
- assert v.shape == (batch, seqlen_k, nheads, d)
777
- assert d <= 128, 'FlashAttention only support head dimensions up to 128'
778
- assert q.dtype == k.dtype == v.dtype, 'All tensors must have the same type'
779
- assert q.dtype in [torch.float16,
780
- torch.bfloat16], 'Only support fp16 and bf16'
781
- assert q.is_cuda and k.is_cuda and v.is_cuda
782
- softmax_scale = softmax_scale or 1.0 / math.sqrt(d)
783
-
784
- has_bias = bias is not None
785
- bias_type = 'none'
786
- if has_bias:
787
- assert bias.dtype in [q.dtype, torch.float]
788
- assert bias.is_cuda
789
- assert bias.dim() == 4
790
- if bias.stride(-1) != 1:
791
- bias = bias.contiguous()
792
- if bias.shape[2:] == (1, seqlen_k):
793
- bias_type = 'vector'
794
- elif bias.shape[2:] == (seqlen_q, seqlen_k):
795
- bias_type = 'matrix'
796
- else:
797
- raise RuntimeError('Last 2 dimensions of bias must be (1, seqlen_k)'
798
- ' or (seqlen_q, seqlen_k)')
799
- if bias.shape[:2] == (1, nheads):
800
- bias = repeat(bias, '1 h ... -> b h ...', b=batch)
801
- elif bias.shape[:2] == (batch, 1):
802
- bias = repeat(bias, 'b 1 ... -> b h ...', h=nheads)
803
- elif bias.shape[:2] == (1, 1):
804
- bias = repeat(bias, '1 h ... -> b h ...', b=batch)
805
- bias = repeat(bias, 'b 1 ... -> b h ...', h=nheads)
806
- assert bias.shape[:2] == (
807
- batch, nheads
808
- ), f'First 2 dimensions of bias must be broadcastible to (batch, nheads) = ({batch, nheads}). Bias has shape: {bias.shape}'
809
- assert bias is not None # for type checking
810
- bias_strides = (bias.stride(0), bias.stride(1),
811
- bias.stride(2)) if has_bias else (0, 0, 0)
812
-
813
- seqlen_q_rounded = math.ceil(seqlen_q / 128) * 128
814
- lse = torch.empty((batch, nheads, seqlen_q_rounded),
815
- device=q.device,
816
- dtype=torch.float32)
817
- tmp = torch.empty((batch, nheads, seqlen_q_rounded),
818
- device=q.device,
819
- dtype=torch.float32)
820
- o = torch.empty_like(q)
821
-
822
- BLOCK_HEADDIM = max(triton.next_power_of_2(d), 16)
823
- # BLOCK = 128
824
- # num_warps = 4 if d <= 64 else 8
825
- grid = lambda META: (triton.cdiv(seqlen_q, META['BLOCK_M']), batch * nheads)
826
- _fwd_kernel[grid]( # type: ignore
827
- q,
828
- k,
829
- v,
830
- bias,
831
- o,
832
- lse,
833
- tmp,
834
- softmax_scale,
835
- q.stride(0),
836
- q.stride(2),
837
- q.stride(1),
838
- k.stride(0),
839
- k.stride(2),
840
- k.stride(1),
841
- v.stride(0),
842
- v.stride(2),
843
- v.stride(1),
844
- *bias_strides,
845
- o.stride(0),
846
- o.stride(2),
847
- o.stride(1),
848
- nheads,
849
- seqlen_q,
850
- seqlen_k,
851
- seqlen_q_rounded,
852
- d,
853
- seqlen_q // 32,
854
- seqlen_k // 32, # key for triton cache (limit number of compilations)
855
- # Can't use kwargs here because triton autotune expects key to be args, not kwargs
856
- # IS_CAUSAL=causal, BLOCK_HEADDIM=d,
857
- bias_type,
858
- causal,
859
- BLOCK_HEADDIM,
860
- # BLOCK_M=BLOCK, BLOCK_N=BLOCK,
861
- # num_warps=num_warps,
862
- # num_stages=1,
863
- )
864
- return o, lse, softmax_scale # softmax_scale could have been updated
865
-
866
-
867
- def _flash_attn_backward(do,
868
- q,
869
- k,
870
- v,
871
- o,
872
- lse,
873
- dq,
874
- dk,
875
- dv,
876
- bias=None,
877
- causal=False,
878
- softmax_scale=None):
879
- # Make sure that the last dimension is contiguous
880
- if do.stride(-1) != 1:
881
- do = do.contiguous()
882
- batch, seqlen_q, nheads, d = q.shape
883
- _, seqlen_k, _, _ = k.shape
884
- # assert d in {16, 32, 64, 128}
885
- assert d <= 128
886
- seqlen_q_rounded = math.ceil(seqlen_q / 128) * 128
887
- assert lse.shape == (batch, nheads, seqlen_q_rounded)
888
- assert q.stride(-1) == k.stride(-1) == v.stride(-1) == o.stride(-1) == 1
889
- assert dq.stride(-1) == dk.stride(-1) == dv.stride(-1) == 1
890
- softmax_scale = softmax_scale or 1.0 / math.sqrt(d)
891
- # dq_accum = torch.zeros_like(q, dtype=torch.float32)
892
- dq_accum = torch.empty_like(q, dtype=torch.float32)
893
- delta = torch.empty_like(lse)
894
- # delta = torch.zeros_like(lse)
895
-
896
- BLOCK_HEADDIM = max(triton.next_power_of_2(d), 16)
897
- grid = lambda META: (triton.cdiv(seqlen_q, META['BLOCK_M']), batch * nheads)
898
- _bwd_preprocess_do_o_dot[grid]( # type: ignore
899
- o,
900
- do,
901
- delta,
902
- o.stride(0),
903
- o.stride(2),
904
- o.stride(1),
905
- do.stride(0),
906
- do.stride(2),
907
- do.stride(1),
908
- nheads,
909
- seqlen_q,
910
- seqlen_q_rounded,
911
- d,
912
- BLOCK_M=128,
913
- BLOCK_HEADDIM=BLOCK_HEADDIM,
914
- )
915
-
916
- has_bias = bias is not None
917
- bias_type = 'none'
918
- if has_bias:
919
- assert bias.dtype in [q.dtype, torch.float]
920
- assert bias.is_cuda
921
- assert bias.dim() == 4
922
- assert bias.stride(-1) == 1
923
- if bias.shape[2:] == (1, seqlen_k):
924
- bias_type = 'vector'
925
- elif bias.shape[2:] == (seqlen_q, seqlen_k):
926
- bias_type = 'matrix'
927
- else:
928
- raise RuntimeError('Last 2 dimensions of bias must be (1, seqlen_k)'
929
- ' or (seqlen_q, seqlen_k)')
930
- if bias.shape[:2] == (1, nheads):
931
- bias = repeat(bias, '1 h ... -> b h ...', b=batch)
932
- elif bias.shape[:2] == (batch, 1):
933
- bias = repeat(bias, 'b 1 ... -> b h ...', h=nheads)
934
- elif bias.shape[:2] == (1, 1):
935
- bias = repeat(bias, '1 h ... -> b h ...', b=batch)
936
- bias = repeat(bias, 'b 1 ... -> b h ...', h=nheads)
937
- assert bias.shape[:2] == (
938
- batch, nheads
939
- ), f'First 2 dimensions of bias must be broadcastible to (batch, nheads) = ({batch, nheads}). Bias has shape: {bias.shape}'
940
- assert bias is not None # type checking
941
- bias_strides = (bias.stride(0), bias.stride(1),
942
- bias.stride(2)) if has_bias else (0, 0, 0)
943
-
944
- # BLOCK_M = 128
945
- # BLOCK_N = 64
946
- # num_warps = 4
947
- grid = lambda META: (triton.cdiv(seqlen_k, META['BLOCK_N'])
948
- if META['SEQUENCE_PARALLEL'] else 1, batch * nheads)
949
- _bwd_kernel[grid]( # type: ignore
950
- q,
951
- k,
952
- v,
953
- bias,
954
- do,
955
- dq_accum,
956
- dk,
957
- dv,
958
- lse,
959
- delta,
960
- softmax_scale,
961
- q.stride(0),
962
- q.stride(2),
963
- q.stride(1),
964
- k.stride(0),
965
- k.stride(2),
966
- k.stride(1),
967
- v.stride(0),
968
- v.stride(2),
969
- v.stride(1),
970
- *bias_strides,
971
- do.stride(0),
972
- do.stride(2),
973
- do.stride(1),
974
- dq_accum.stride(0),
975
- dq_accum.stride(2),
976
- dq_accum.stride(1),
977
- dk.stride(0),
978
- dk.stride(2),
979
- dk.stride(1),
980
- dv.stride(0),
981
- dv.stride(2),
982
- dv.stride(1),
983
- nheads,
984
- seqlen_q,
985
- seqlen_k,
986
- seqlen_q_rounded,
987
- d,
988
- seqlen_q // 32,
989
- seqlen_k // 32, # key for triton cache (limit number of compilations)
990
- # Can't use kwargs here because triton autotune expects key to be args, not kwargs
991
- # IS_CAUSAL=causal, BLOCK_HEADDIM=d,
992
- bias_type,
993
- causal,
994
- BLOCK_HEADDIM,
995
- # SEQUENCE_PARALLEL=False,
996
- # BLOCK_M=BLOCK_M, BLOCK_N=BLOCK_N,
997
- # num_warps=num_warps,
998
- # num_stages=1,
999
- )
1000
- dq.copy_(dq_accum)
1001
-
1002
-
1003
- class _FlashAttnQKVPackedFunc(torch.autograd.Function):
1004
-
1005
- @staticmethod
1006
- def forward(ctx, qkv, bias=None, causal=False, softmax_scale=None):
1007
- """Forward pass for packed FlashAttention.
1008
-
1009
- Args:
1010
- ctx: autograd context
1011
- qkv: (batch, seqlen, 3, nheads, headdim)
1012
- bias: optional, shape broadcastible to (batch, nheads, seqlen, seqlen).
1013
- For example, ALiBi mask for causal would have shape (1, nheads, 1, seqlen).
1014
- ALiBi mask for non-causal would have shape (1, nheads, seqlen, seqlen)
1015
- causal (bool): whether to incorporate causal attention masking
1016
- softmax_scale (float, optional): scale factor for softmax
1017
- """
1018
- # Make sure that the last dimension is contiguous
1019
- if qkv.stride(-1) != 1:
1020
- qkv = qkv.contiguous()
1021
- o, lse, ctx.softmax_scale = _flash_attn_forward(
1022
- qkv[:, :, 0],
1023
- qkv[:, :, 1],
1024
- qkv[:, :, 2],
1025
- bias=bias,
1026
- causal=causal,
1027
- softmax_scale=softmax_scale)
1028
- ctx.save_for_backward(qkv, o, lse, bias)
1029
- ctx.causal = causal
1030
- return o
1031
-
1032
- @staticmethod
1033
- def backward(ctx, do):
1034
- qkv, o, lse, bias = ctx.saved_tensors
1035
- assert not ctx.needs_input_grad[
1036
- 1], 'FlashAttention does not support bias gradient yet'
1037
- # Triton's autotune causes the Tensor._version to change, and so Pytorch autograd
1038
- # does a memcpy. To avoid this we run in inference_mode, which doesn't track the version.
1039
- with torch.inference_mode():
1040
- dqkv = torch.empty_like(qkv)
1041
- _flash_attn_backward(do,
1042
- qkv[:, :, 0],
1043
- qkv[:, :, 1],
1044
- qkv[:, :, 2],
1045
- o,
1046
- lse,
1047
- dqkv[:, :, 0],
1048
- dqkv[:, :, 1],
1049
- dqkv[:, :, 2],
1050
- bias=bias,
1051
- causal=ctx.causal,
1052
- softmax_scale=ctx.softmax_scale)
1053
- return dqkv, None, None, None
1054
-
1055
-
1056
- flash_attn_qkvpacked_func = _FlashAttnQKVPackedFunc.apply
1057
-
1058
-
1059
- class _FlashAttnFunc(torch.autograd.Function):
1060
-
1061
- @staticmethod
1062
- def forward(ctx, q, k, v, bias=None, causal=False, softmax_scale=None):
1063
- """Forward pass for FlashAttention.
1064
-
1065
- Args:
1066
- ctx: autograd context
1067
- q: (batch_size, seqlen_q, nheads, headdim)
1068
- k: (batch_size, seqlen_k, nheads, headdim)
1069
- v: (batch_size, seqlen_k, nheads, headdim)
1070
- bias: optional, shape broadcastible to (batch, nheads, seqlen_q, seqlen_k).
1071
- For example, ALiBi mask for causal would have shape (1, nheads, 1, seqlen_k).
1072
- ALiBi mask for non-causal would have shape (1, nheads, seqlen_q, seqlen_k)
1073
- causal (bool): whether to incorporate causal attention masking
1074
- softmax_scale (float, optional): scale factor for softmax
1075
- """
1076
- # Make sure that the last dimension is contiguous
1077
- q, k, v = [
1078
- x if x.stride(-1) == 1 else x.contiguous() for x in [q, k, v]
1079
- ]
1080
- o, lse, ctx.softmax_scale = _flash_attn_forward(
1081
- q, k, v, bias=bias, causal=causal, softmax_scale=softmax_scale)
1082
- ctx.save_for_backward(q, k, v, o, lse, bias)
1083
- ctx.causal = causal
1084
- return o
1085
-
1086
- @staticmethod
1087
- def backward(ctx, do):
1088
- q, k, v, o, lse, bias = ctx.saved_tensors
1089
- assert not ctx.needs_input_grad[
1090
- 3], 'FlashAttention does not support bias gradient yet'
1091
- # Triton's autotune causes the Tensor._version to change, and so Pytorch autograd
1092
- # does a memcpy. To avoid this we run in inference_mode, which doesn't track the version.
1093
- with torch.inference_mode():
1094
- dq = torch.empty_like(q)
1095
- dk = torch.empty_like(k)
1096
- dv = torch.empty_like(v)
1097
- _flash_attn_backward(do,
1098
- q,
1099
- k,
1100
- v,
1101
- o,
1102
- lse,
1103
- dq,
1104
- dk,
1105
- dv,
1106
- bias=bias,
1107
- causal=ctx.causal,
1108
- softmax_scale=ctx.softmax_scale)
1109
- return dq, dk, dv, None, None, None
1110
-
1111
-
1112
- flash_attn_func = _FlashAttnFunc.apply
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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