78 transformer blocks › 75 MoE blocks › Mixture of experts
MoE update
×tensorhidden_states · 582
The MoE update added to the residual stream.
- shape
- [B batch, T positions, 6144 d]
Sources
Contextual evidence from MoE residual addition
A block applies input RMSNorm, attention and a residual addition, then post-attention RMSNorm, the feed-forward network and a second residual addition; the first first_k_dense_replace blocks use the dense MLP, the rest MoE.
block · huggingface/transformers / modeling_glm_moe_dsa.py
Pinned revision 5e4d6304de55 ↗ · lines 586–627
Read code excerpt
class GlmMoeDsaDecoderLayer(GradientCheckpointingLayer):
def __init__(self, config: GlmMoeDsaConfig, layer_idx: int):
super().__init__()
self.hidden_size = config.hidden_size
self.self_attn = GlmMoeDsaAttention(config, layer_idx)
self.mlp = GlmMoeDsaMoE(config) if config.mlp_layer_types[layer_idx] == "sparse" else GlmMoeDsaMLP(config)
self.input_layernorm = GlmMoeDsaRMSNorm(config.hidden_size, config.rms_norm_eps)
self.post_attention_layernorm = GlmMoeDsaRMSNorm(config.hidden_size, config.rms_norm_eps)
def forward(
self,
hidden_states: torch.Tensor,
attention_mask: torch.Tensor | None = None,
position_ids: torch.LongTensor | None = None,
past_key_values: Cache | None = None,
use_cache: bool | None = False,
position_embeddings: tuple[torch.Tensor, torch.Tensor] | None = None,
prev_topk_indices: torch.Tensor | None = None, # MAIN DIFF with DSV3.2
**kwargs: Unpack[TransformersKwargs],
) -> tuple[torch.Tensor, torch.Tensor | None]:
residual = hidden_states
hidden_states = self.input_layernorm(hidden_states)
# Self Attention
hidden_states, _, topk_indices = self.self_attn(
hidden_states=hidden_states,
attention_mask=attention_mask,
position_ids=position_ids,
past_key_values=past_key_values,
use_cache=use_cache,
position_embeddings=position_embeddings,
prev_topk_indices=prev_topk_indices, # MAIN DIFF with DSV3.2
**kwargs,
)
hidden_states = residual + hidden_states
residual = hidden_states
hidden_states = self.post_attention_layernorm(hidden_states)
hidden_states = self.mlp(hidden_states)
hidden_states = residual + hidden_states
return hidden_states, topk_indicesContextual evidence from MoE residual addition
RMSNorm owns one gain per feature; it normalizes in float32, casts back to the input precision and multiplies by the gain.
rmsnorm · huggingface/transformers / modeling_glm_moe_dsa.py
Pinned revision 5e4d6304de55 ↗ · lines 48–62
Read code excerpt
class GlmMoeDsaRMSNorm(nn.Module):
def __init__(self, hidden_size, eps: float = 1e-6) -> None:
"""
GlmMoeDsaRMSNorm is equivalent to T5LayerNorm
"""
super().__init__()
self.weight = nn.Parameter(torch.ones(hidden_size))
self.variance_epsilon = eps
def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
input_dtype = hidden_states.dtype
hidden_states = hidden_states.to(torch.float32)
variance = hidden_states.pow(2).mean(-1, keepdim=True)
hidden_states = hidden_states * torch.rsqrt(variance + self.variance_epsilon)
return self.weight * hidden_states.to(input_dtype)Contextual evidence from Add shared output
Each token’s output is the router-weighted sum of its selected experts plus the shared expert applied to every token.
moe-forward · huggingface/transformers / modeling_glm_moe_dsa.py
Pinned revision 5e4d6304de55 ↗ · lines 535–583
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def forward(
self,
hidden_states: torch.Tensor,
top_k_index: torch.Tensor,
top_k_weights: torch.Tensor,
) -> torch.Tensor:
final_hidden_states = torch.zeros_like(hidden_states)
with torch.no_grad():
expert_mask = torch.nn.functional.one_hot(top_k_index, num_classes=self.num_experts + 1)
expert_mask = expert_mask.permute(2, 1, 0)
expert_hit = torch.greater(expert_mask.sum(dim=(-1, -2)), 0).nonzero()
for expert_idx in expert_hit:
expert_idx = expert_idx[0]
if expert_idx == self.num_experts:
continue
top_k_pos, token_idx = torch.where(expert_mask[expert_idx])
current_state = hidden_states[token_idx]
gate, up = nn.functional.linear(current_state, self.gate_up_proj[expert_idx]).chunk(2, dim=-1)
current_hidden_states = self.act_fn(gate) * up
current_hidden_states = nn.functional.linear(current_hidden_states, self.down_proj[expert_idx])
current_hidden_states = current_hidden_states * top_k_weights[token_idx, top_k_pos, None]
final_hidden_states.index_add_(0, token_idx, current_hidden_states.to(final_hidden_states.dtype))
return final_hidden_states… lines 560–575 omitted …
def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
residuals = hidden_states
orig_shape = hidden_states.shape
_, topk_weights, topk_indices = self.gate(hidden_states)
hidden_states = hidden_states.view(-1, hidden_states.shape[-1])
hidden_states = self.experts(hidden_states, topk_indices, topk_weights).view(*orig_shape)
hidden_states = hidden_states + self.shared_experts(residuals)
return hidden_states