Shared expert

Reference code deepseek-ai/DeepSeek-V3.2-Exp @ 87e509a · checkpoint, tokenizer and tensors not verified · How to read

in
xffnx_{\mathrm{ffn}} [B batch, T positions, 7168 d]
out
ysharedy^{\mathrm{shared}} [B batch, T positions, 7168 d]
parameters
44,040,192 · × 58 MoE blocks = 2,554,331,136
Parameters

44,040,192 parameters per instance, across its learned components

Exact per-instance accounting
ComponentCalculationParameters
Gate projection7,168×2,0487{,}168 \times 2{,}04814,680,064
Up projection7,168×2,0487{,}168 \times 2{,}04814,680,064
Down projection2,048×7,1682{,}048 \times 7{,}16814,680,064
Per-instance total44,040,192

Across 58 independent MoE blocks: 44,040,192×58=2,554,331,13644{,}040{,}192 \times 58 = 2{,}554{,}331{,}136 parameters.

Derived from the pinned reference configuration and inference code. Checkpoint tensors have not been independently counted; FP8 block scales and the multi-token-prediction module are not counted.

Explanation

Its 2,048 hidden features are n_shared_experts × moe_inter_dim (model.py 778).

Codemodel.py 629–803
model.py 770–778
        self.n_routed_experts = args.n_routed_experts
        self.n_local_experts = args.n_routed_experts // world_size
        self.n_activated_experts = args.n_activated_experts
        self.experts_start_idx = rank * self.n_local_experts
        self.experts_end_idx = self.experts_start_idx + self.n_local_experts
        self.gate = Gate(args)
        self.experts = nn.ModuleList([Expert(args.dim, args.moe_inter_dim) if self.experts_start_idx <= i < self.experts_end_idx else None
                                      for i in range(self.n_routed_experts)])
        self.shared_experts = MLP(args.dim, args.n_shared_experts * args.moe_inter_dim, reduce_output=False)
model.py 790–803
        shape = x.size()
        x = x.view(-1, self.dim)
        weights, indices = self.gate(x)
        y = torch.zeros_like(x, dtype=torch.float32)
        counts = torch.bincount(indices.flatten(), minlength=self.n_routed_experts).tolist()
        for i in range(self.experts_start_idx, self.experts_end_idx):
            if counts[i] == 0:
                continue
            expert = self.experts[i]
            idx, top = torch.where(indices == i)
            y[idx] += expert(x[idx]) * weights[idx, top, None]
        y += self.shared_experts(x)
        if world_size > 1:
            dist.all_reduce(y)
model.py 629–631
        self.w1 = ColumnParallelLinear(dim, inter_dim)
        self.w2 = RowParallelLinear(inter_dim, dim, reduce_output=reduce_output)
        self.w3 = ColumnParallelLinear(dim, inter_dim)
model.py 643
        return self.w2((F.silu(self.w1(x).float()) * self.w3(x).float()).type_as(x))
Sources3

Direct evidence

The MoE layer holds the router, the routed experts and one shared expert MLP of n_shared_experts × moe_inter_dim features.

moe-init · deepseek-ai/DeepSeek-V3.2-Exp / inference/model.py
Pinned revision 87e509a2e5a1 ↗ · lines 770–778

Read code excerpt
        self.n_routed_experts = args.n_routed_experts
        self.n_local_experts = args.n_routed_experts // world_size
        self.n_activated_experts = args.n_activated_experts
        self.experts_start_idx = rank * self.n_local_experts
        self.experts_end_idx = self.experts_start_idx + self.n_local_experts
        self.gate = Gate(args)
        self.experts = nn.ModuleList([Expert(args.dim, args.moe_inter_dim) if self.experts_start_idx <= i < self.experts_end_idx else None
                                      for i in range(self.n_routed_experts)])
        self.shared_experts = MLP(args.dim, args.n_shared_experts * args.moe_inter_dim, reduce_output=False)

Direct evidence

Each token’s output is the router-weighted sum of its selected experts plus the shared expert applied to every token.

moe-forward · deepseek-ai/DeepSeek-V3.2-Exp / inference/model.py
Pinned revision 87e509a2e5a1 ↗ · lines 790–803

Read code excerpt
        shape = x.size()
        x = x.view(-1, self.dim)
        weights, indices = self.gate(x)
        y = torch.zeros_like(x, dtype=torch.float32)
        counts = torch.bincount(indices.flatten(), minlength=self.n_routed_experts).tolist()
        for i in range(self.experts_start_idx, self.experts_end_idx):
            if counts[i] == 0:
                continue
            expert = self.experts[i]
            idx, top = torch.where(indices == i)
            y[idx] += expert(x[idx]) * weights[idx, top, None]
        y += self.shared_experts(x)
        if world_size > 1:
            dist.all_reduce(y)

Direct evidence

The dense feed-forward network is a SwiGLU MLP: w2(silu(w1 x) ⊙ w3 x).

mlp · deepseek-ai/DeepSeek-V3.2-Exp / inference/model.py
Pinned revision 87e509a2e5a1 ↗ · lines 629–643

Read code excerpt
        self.w1 = ColumnParallelLinear(dim, inter_dim)
        self.w2 = RowParallelLinear(inter_dim, dim, reduce_output=reduce_output)
        self.w3 = ColumnParallelLinear(dim, inter_dim)

… lines 632–642 omitted …

        return self.w2((F.silu(self.w1(x).float()) * self.w3(x).float()).type_as(x))