diff --git a/fastchat/train/llama_xformers_attn_monkey_patch.py b/fastchat/train/llama_xformers_attn_monkey_patch.py new file mode 100644 index 000000000..f8351e41c --- /dev/null +++ b/fastchat/train/llama_xformers_attn_monkey_patch.py @@ -0,0 +1,129 @@ +""" +Directly copied the code from https://raw.githubusercontent.com/oobabooga/text-generation-webui/main/modules/llama_attn_hijack.py and made some adjustments +""" + +import logging +import math +from typing import Optional, Tuple + +import torch +import transformers.models.llama.modeling_llama +from torch import nn + +try: + import xformers.ops +except ImportError: + logging.error("xformers not found! Please install it before trying to use it.") + + +def replace_llama_attn_with_xformers_attn(): + transformers.models.llama.modeling_llama.LlamaAttention.forward = xformers_forward + + +def xformers_forward( + self, + hidden_states: torch.Tensor, + attention_mask: Optional[torch.Tensor] = None, + position_ids: Optional[torch.LongTensor] = None, + past_key_value: Optional[Tuple[torch.Tensor]] = None, + output_attentions: bool = False, + use_cache: bool = False, +) -> Tuple[torch.Tensor, Optional[torch.Tensor], Optional[Tuple[torch.Tensor]]]: + # pylint: disable=duplicate-code + bsz, q_len, _ = hidden_states.size() + + query_states = ( + self.q_proj(hidden_states) + .view(bsz, q_len, self.num_heads, self.head_dim) + .transpose(1, 2) + ) + key_states = ( + self.k_proj(hidden_states) + .view(bsz, q_len, self.num_heads, self.head_dim) + .transpose(1, 2) + ) + value_states = ( + self.v_proj(hidden_states) + .view(bsz, q_len, self.num_heads, self.head_dim) + .transpose(1, 2) + ) + + kv_seq_len = key_states.shape[-2] + if past_key_value is not None: + kv_seq_len += past_key_value[0].shape[-2] + cos, sin = self.rotary_emb(value_states, seq_len=kv_seq_len) + ( + query_states, + key_states, + ) = transformers.models.llama.modeling_llama.apply_rotary_pos_emb( + query_states, key_states, cos, sin, position_ids + ) + # [bsz, nh, t, hd] + + if past_key_value is not None: + # reuse k, v, self_attention + key_states = torch.cat([past_key_value[0], key_states], dim=2) + value_states = torch.cat([past_key_value[1], value_states], dim=2) + + past_key_value = (key_states, value_states) if use_cache else None + + # We only apply xformers optimizations if we don't need to output the whole attention matrix + if not output_attentions: + query_states = query_states.transpose(1, 2) + key_states = key_states.transpose(1, 2) + value_states = value_states.transpose(1, 2) + + # This is a nasty hack. We know attention_mask in transformers is either LowerTriangular or all Zeros. + # We therefore check if one element in the upper triangular portion is zero. If it is, then the mask is all zeros. + if attention_mask is None or attention_mask[0, 0, 0, 1] == 0: + # input and output should be of form (bsz, q_len, num_heads, head_dim) + attn_output = xformers.ops.memory_efficient_attention( + query_states, key_states, value_states, attn_bias=None + ) + else: + # input and output should be of form (bsz, q_len, num_heads, head_dim) + attn_output = xformers.ops.memory_efficient_attention( + query_states, + key_states, + value_states, + attn_bias=xformers.ops.LowerTriangularMask(), + ) + attn_weights = None + else: + attn_weights = torch.matmul( + query_states, key_states.transpose(2, 3) + ) / math.sqrt(self.head_dim) + + if attn_weights.size() != (bsz, self.num_heads, q_len, kv_seq_len): + raise ValueError( + f"Attention weights should be of size {(bsz * self.num_heads, q_len, kv_seq_len)}, but is" + f" {attn_weights.size()}" + ) + + if attention_mask is not None: + if attention_mask.size() != (bsz, 1, q_len, kv_seq_len): + raise ValueError( + f"Attention mask should be of size {(bsz, 1, q_len, kv_seq_len)}, but is {attention_mask.size()}" + ) + attn_weights = attn_weights + attention_mask + attn_weights = torch.max( + attn_weights, torch.tensor(torch.finfo(attn_weights.dtype).min) + ) + + # upcast attention to fp32 + attn_weights = nn.functional.softmax( + attn_weights, dim=-1, dtype=torch.float32 + ).to(query_states.dtype) + attn_output = torch.matmul(attn_weights, value_states) + + if attn_output.size() != (bsz, self.num_heads, q_len, self.head_dim): + raise ValueError( + f"`attn_output` should be of size {(bsz, self.num_heads, q_len, self.head_dim)}, but is" + f" {attn_output.size()}" + ) + + attn_output = attn_output.transpose(1, 2) + + attn_output = attn_output.reshape(bsz, q_len, self.hidden_size) + attn_output = self.o_proj(attn_output) + return attn_output, attn_weights, past_key_value diff --git a/fastchat/train/train_xformers.py b/fastchat/train/train_xformers.py new file mode 100644 index 000000000..0eb2badd5 --- /dev/null +++ b/fastchat/train/train_xformers.py @@ -0,0 +1,13 @@ +# Make it more memory efficient by monkey patching the LLaMA model with xformers attention. + +# Need to call this before importing transformers. +from fastchat.train.llama_xformers_attn_monkey_patch import ( + replace_llama_attn_with_xformers_attn, +) + +replace_llama_attn_with_xformers_attn() + +from fastchat.train.train import train + +if __name__ == "__main__": + train()