115 lines
4.8 KiB
Python
115 lines
4.8 KiB
Python
#
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# Copyright 2016 The BigDL Authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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# Some parts of this file is adapted from
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# https://github.com/huggingface/transformers/blob/main/src/transformers/models/mixtral/modeling_mixtral.py
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# coding=utf-8
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# Copyright 2023 Mistral AI and the HuggingFace Inc. team. All rights reserved.
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#
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# This code is based on EleutherAI's GPT-NeoX library and the GPT-NeoX
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# and OPT implementations in this library. It has been modified from its
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# original forms to accommodate minor architectural differences compared
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# to GPT-NeoX and OPT used by the Meta AI team that trained the model.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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""" PyTorch Phixtral model."""
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import torch
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import torch.nn.functional as F
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def phixtral_moeblock_forward(self, hidden_states: torch.Tensor):
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batch_size, sequence_length, hidden_dim = hidden_states.shape
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hidden_states = hidden_states.view(-1, hidden_dim)
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bs = hidden_states.shape[0]
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# router_logits: (batch * sequence_length, n_experts)
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router_logits = self.gate(hidden_states)
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num_local_experts = len(self.mlp)
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routing_weights = F.softmax(router_logits, dim=1, dtype=torch.float)
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top_k = self.num_experts_per_tok
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routing_weights, selected_experts = torch.topk(routing_weights, top_k, dim=-1)
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routing_weights /= routing_weights.sum(dim=-1, keepdim=True)
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# we cast back to the input dtype
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routing_weights = routing_weights.to(hidden_states.dtype)
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if bs > 1:
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final_hidden_states = torch.zeros(
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(batch_size * sequence_length, hidden_dim),
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dtype=hidden_states.dtype,
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device=hidden_states.device
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)
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# One hot encode the selected experts to create an expert mask
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# this will be used to easily index which expert is going to be sollicitated
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expert_mask = torch.nn.functional.one_hot(selected_experts,
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num_classes=num_local_experts).permute(2, 1, 0)
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# Loop over all available experts in the model and perform the computation on each expert
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for expert_idx in range(num_local_experts):
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expert_layer = self.mlp[expert_idx]
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idx, top_x = torch.where(expert_mask[expert_idx])
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if top_x.shape[0] == 0:
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continue
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# in torch it is faster to index using lists than torch tensors
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top_x_list = top_x.tolist()
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idx_list = idx.tolist()
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# Index the correct hidden states and compute the expert hidden state for
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# the current expert. We need to make sure to multiply the output hidden
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# states by `routing_weights` on the corresponding tokens (top-1 and top-2)
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current_state = hidden_states[None, top_x_list].reshape(-1, hidden_dim)
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current_hidden_states = expert_layer(current_state)
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# However `index_add_` only support torch tensors for indexing so we'll use
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# the `top_x` tensor here.
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final_hidden_states.index_add_(0, top_x, current_hidden_states.to(hidden_states.dtype))
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else:
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selected_experts = selected_experts[0].cpu().tolist()
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for idx in range(top_k):
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exp_id = selected_experts[idx]
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expert_layer = self.mlp[exp_id]
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weight = routing_weights[:, idx]
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if idx == 0:
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final_hidden_states = expert_layer(hidden_states)
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else:
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final_hidden_states = final_hidden_states + expert_layer(hidden_states)
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final_hidden_states = final_hidden_states.reshape(batch_size, sequence_length, hidden_dim)
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return final_hidden_states
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def phixtral_mlp_forward(
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self,
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x: torch.Tensor,
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) -> torch.Tensor:
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hidden_states = self.fc1(x)
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hidden_states = self.act(hidden_states)
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hidden_states = self.fc2(hidden_states)
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return hidden_states
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