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https://github.com/Vision-CAIR/MiniGPT-4.git
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259 lines
12 KiB
Python
259 lines
12 KiB
Python
import copy
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import pickle
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import torch
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import torch.nn as nn
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import torch.nn.functional as F
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class MoELayer(nn.Module):
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def __init__(self, hidden_size, expert, num_experts, route_method, topk=1, use_balance_loss=True, weight_type='raw_prob'):
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# remove hash list
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nn.Module.__init__(self)
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self.num_experts = num_experts
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self.experts = nn.ModuleList([copy.deepcopy(expert) for i in range(num_experts)])
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self.route_method = route_method
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self.topk = topk
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self.use_balance_loss = use_balance_loss
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self.weight_type = weight_type
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if route_method in ["gate-token", "gate-sentence", "gate-sentence-cls"]:
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gate = nn.Linear(hidden_size, num_experts, bias=False).float()
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elif route_method in ["gate-sentence-post"]:
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gate = nn.Linear(hidden_size, 1, bias=False).float()
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# self.gates = nn.ModuleList([copy.deepcopy(gate) for i in range(num_experts)])
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elif route_method in ["gate-sentence-post-cosine"]:
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gate = nn.Parameter(torch.rand(hidden_size)).float()
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else:
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raise KeyError("Routing method not supported.")
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self.gate = gate
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def _balancing_loss(self, prob_gate, num_tokens):
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# From MOEBERT
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# compute the load balancing loss
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# prob_gate，是 [bz, num_expert]，每个样本被分配给每个expert的概率
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# 等价于 VMOE 中 _gshard_auxiliary_loss
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P = prob_gate.mean(0) # torch.Size([num_expert]) 每个expert被分配到样本的平均概率
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temp = num_tokens.float()
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f = temp / temp.sum(0, keepdim=True) # 每个expert被分配的sample比例
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balance_loss = self.num_experts * torch.sum(P * f)
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return balance_loss
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def _importance_auxiliary_loss(self, prob_gate):
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# From VMOE
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# _importance_auxiliary_loss
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axis = tuple(range(prob_gate.ndim - 1)) # All except last.
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importance_per_expert = torch.sum(prob_gate, dim=axis)
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std_importance_per_expert = torch.std(importance_per_expert)
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mean_importance_per_expert = torch.mean(importance_per_expert)
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# Compute coefficient of variation (i.e. std/mean) squared.
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return (std_importance_per_expert / mean_importance_per_expert)**2
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def _forward_gate_token(self, x):
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bsz, seq_len, dim = x.size()
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x = x.view(-1, dim)
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logits_gate = self.gate(x)
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prob_gate = F.softmax(logits_gate, dim=-1)
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gate = torch.argmax(prob_gate, dim=-1)
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order = gate.argsort(0)
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num_tokens = F.one_hot(gate, self.num_experts).gt(0).sum(0)
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gate_load = num_tokens.clone()
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x = x[order] # reorder according to expert number
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x = x.split(num_tokens.tolist(), dim=0) # a list of length self.num_experts
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# compute the load balancing loss
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P = prob_gate.mean(0)
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temp = num_tokens.float()
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f = temp / temp.sum(0, keepdim=True)
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balance_loss = self.num_experts * torch.sum(P * f)
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prob_gate = prob_gate.gather(dim=1, index=gate.unsqueeze(1))
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prob_gate = prob_gate[order]
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prob_gate = prob_gate.split(num_tokens.tolist(), dim=0)
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def forward_expert(input_x, prob_x, expert_idx):
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input_x = self.experts[expert_idx].forward(input_x)
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input_x = input_x * prob_x
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return input_x
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x = [forward_expert(x[i], prob_gate[i], i) for i in range(self.num_experts)]
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x = torch.vstack(x)
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x = x[order.argsort(0)] # restore original order
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x = x.view(bsz, seq_len, dim)
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return x, balance_loss, gate_load
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def _forward_gate_sentence_post(self, x, attention_mask):
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"""
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x: query_attention_output; torch.Size([bz, 32, 768])
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attention_mask: torch.ones([bz, 32])
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bz = 4
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x = torch.randn(bz,32,768)
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attention_mask = torch.ones([bz, 32])
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"""
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attention_mask = torch.ones(attention_mask.shape[0], attention_mask.shape[1]).to(x.device)
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x_masked = x * attention_mask.unsqueeze(-1) # torch.Size([bz, 32, 768])
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def forward_expert(input_x, expert_idx):
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# input_x += torch.randn(4,32,768)
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# return input_x
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output_x = self.experts[expert_idx].forward(input_x)
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return output_x
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outputs = list()
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logits_gate_lst = list()
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for expert_idx in range(self.num_experts):
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output_x = forward_expert(x_masked, expert_idx)
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outputs.append(output_x.unsqueeze(0))
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output_x_aver = output_x.sum(1) / attention_mask.unsqueeze(-1).sum(1) # torch.Size([bz, 768])
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# gate_acore = self.gates[expert_idx](output_x_aver)
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if self.route_method=="gate-sentence-post-cosine":
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# gate_score = F.cosine_similarity(self.gate.weight, output_x_aver,dim=1).unsqueeze(1)
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gate_score = F.cosine_similarity(self.gate, output_x_aver,dim=1).unsqueeze(1)
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else:
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gate_score = self.gate(output_x_aver)
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logits_gate_lst.append(gate_score)
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candidate_output = torch.cat(outputs) # torch.Size([num_expert, bz, 32, 768])
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logits_gate = torch.cat(logits_gate_lst,dim=1)# torch.Size([bz, num_expert])
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prob_gate = F.softmax(logits_gate, dim=-1) # torch.Size([bz, num_experts])
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topk_values, gate = torch.topk(prob_gate, self.topk, dim=1) # gate, 每个样本被分配的expert: torch.Size([bz, topk])
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num_sentences = F.one_hot(gate, self.num_experts).sum(1).gt(0).sum(0) # 每个expert被分配的样本数 torch.Size([num_expert])
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gate_load = num_sentences.clone()
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# load balancing loss
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if self.use_balance_loss:
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balance_loss = self._balancing_loss(prob_gate, num_sentences)
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else:
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balance_loss = 0.0
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# importance loss
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importance_loss = self._importance_auxiliary_loss(prob_gate)
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prob_gate_topk = torch.zeros_like(prob_gate)
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prob_gate_topk.scatter_(1, gate, topk_values)
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if self.weight_type == 'average':
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# torch.Size([bz, num_expert]) 未选中的expert prob_gate_norm为0
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prob_gate_normalized = prob_gate_topk / prob_gate_topk.sum(dim=1, keepdim=True)
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elif self.weight_type == 'raw_prob':
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prob_gate_normalized = prob_gate_topk
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elif self.weight_type == 'softmax_norm':
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prob_gate_normalized = F.softmax(prob_gate_topk, dim=-1) # torch.Size([bz, num_expert])
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candidate_output_ad = torch.permute(candidate_output, (1, 0, 2, 3)) # torch.Size([bz, num_expert, 32, 768])
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results = prob_gate_normalized.unsqueeze(-1).unsqueeze(-1) * candidate_output_ad # torch.Size([bz, num_expert, 32, 768])
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moe_result = torch.sum(results, dim=1) # torch.Size([bz, 32, 768])
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# import pdb;pdb.set_trace()
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return moe_result, (balance_loss+importance_loss), prob_gate_normalized
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def router(self, x, attention_mask):
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# Prepare input x
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attention_mask = torch.ones(attention_mask.shape[0], attention_mask.shape[1]).to(x.device)
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x_masked = x * attention_mask.unsqueeze(-1) # torch.Size([bz, 32, 768])
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x_average = torch.mean(x_masked, dim=1) # torch.Size([bz, 768])
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# Forward Gate
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# logits_gate: [bz, num_experts]
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logits_gate = self.gate(x_average)
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# Probabilities for each sample of what expert it should be sent to.
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# prob_gate: [bz, num_experts]
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prob_gate = F.softmax(logits_gate, dim=-1)
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# Get Top-K experts for each sample
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# gate: [bz, topk]
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# select_prob_gate: [bz, topk]
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select_prob_gate, gate = torch.topk(prob_gate, self.topk, dim=1)
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# Reshap Prob_gate & Gate
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# expert_mask: [batch_size, topk, num_experts]
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# expert_gate: [batch_size, topk, num_experts]
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# combine_tensor: [batch_size, num_experts]
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expert_mask = F.one_hot(gate, self.num_experts)
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expert_gate = select_prob_gate.unsqueeze(-1) * expert_mask
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combine_tensor = torch.sum(expert_gate, dim=1)
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# Calculate Balancing Loss
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if self.use_balance_loss:
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num_sentences = F.one_hot(gate, self.num_experts).sum(1).gt(0).sum(0) # 每个expert被分配的样本数 torch.Size([num_expert])
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balance_loss = self._balancing_loss(prob_gate, num_sentences)
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else:
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balance_loss = 0.0
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# Calculate Importance Loss
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importance_loss = self._importance_auxiliary_loss(prob_gate)
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return expert_mask, combine_tensor, balance_loss, importance_loss
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def cls_router(self, cls_hidden=None):
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logits_gate = self.gate(cls_hidden.squeeze(1))
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prob_gate = F.softmax(logits_gate, dim=-1)
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select_prob_gate, gate = torch.topk(prob_gate, self.topk, dim=1)
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expert_mask = F.one_hot(gate, self.num_experts)
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expert_gate = select_prob_gate.unsqueeze(-1) * expert_mask
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combine_tensor = torch.sum(expert_gate, dim=1)
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if self.use_balance_loss:
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num_sentences = F.one_hot(gate, self.num_experts).sum(1).gt(0).sum(0) # 每个expert被分配的样本数 torch.Size([num_expert])
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balance_loss = self._balancing_loss(prob_gate, num_sentences)
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else:
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balance_loss = 0.0
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importance_loss = self._importance_auxiliary_loss(prob_gate)
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return expert_mask, combine_tensor, balance_loss, importance_loss
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def _forward_gate_sentence(self, x, attention_mask, cls_hidden=None):
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"""
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x: query_attention_output , torch.Size([bz, 32, 768])
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attention_mask: torch.ones([bz, 32])
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### Notice:
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the raw version of expert_attention_mask is the extended_attention_mask,
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which will be add to attention_score directly
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the values of extended_attention_mask are -0.0 or -10000
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it should be adjust to 1/0 version to be processed by experts
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"""
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# Forward Router
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if self.route_method=="gate-sentence-cls":
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expert_mask, combine_tensor, balance_loss, importance_loss = self.cls_router(cls_hidden)
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else:
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expert_mask, combine_tensor, balance_loss, importance_loss = self.router(x, attention_mask)
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# Forward Expert FFN
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result = []
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for expert_idx in range(self.num_experts):
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output_x = self.experts[expert_idx].forward(x)
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result.append(output_x.unsqueeze(0))
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expert_output = torch.cat(result).permute(1,0,2,3) # torch.Size([batch_size, num_expert, num_tokens, hidden_states])
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# multiply outputs of experts by the routing probability
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if self.weight_type == 'raw_prob':
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expert_outputs_combined = expert_output * combine_tensor.unsqueeze(-1).unsqueeze(-1) # torch.Size([batch_size, num_expert, num_tokens, hidden_states])
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elif self.weight_type == 'no_prob':
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combine_index = torch.sum(expert_mask, dim=1)
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expert_outputs_combined = expert_output * combine_index.unsqueeze(-1).unsqueeze(-1) # torch.Size([batch_size, num_expert, num_tokens, hidden_states])
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outputs = torch.sum(expert_outputs_combined, dim=1) # torch.Size([batch_size, num_tokens, hidden_states])
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return outputs, (balance_loss+importance_loss), combine_tensor
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def forward(self, x, attention_mask, cls_hidden=None):
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# import pdb; pdb.set_trace()
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if self.route_method == "gate-token":
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x, balance_loss, gate_load = self._forward_gate_token(x)
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elif self.route_method == "gate-sentence":
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x, balance_loss, gate_load = self._forward_gate_sentence(x, attention_mask)
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elif self.route_method in ["gate-sentence-post", "gate-sentence-post-cosine"]:
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x, balance_loss, gate_load = self._forward_gate_sentence_post(x, attention_mask)
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elif self.route_method == "gate-sentence-cls":
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x, balance_loss, gate_load = self._forward_gate_sentence(x, attention_mask, cls_hidden)
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else:
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raise KeyError("Routing method not supported.")
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return x, balance_loss, gate_load
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