Sparse attention

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

in
Q~\tilde Q [B batch, 128 heads, 1 positions, 576 latent + rotary]K^\hat K [B batch, 1001 cached positions, 576 latent + rotary]c^KV\hat c^{KV} [B batch, 1001 cached positions, 512 kv latent]MselM^{\mathrm{sel}} [B batch, 1 queries, 1001 keys]
out
Δattn\Delta_{\mathrm{attn}} [B batch, 1 positions, 7168 d]
parameters
117,440,512 · × 58 MoE blocks = 6,811,549,696
mode
decode · P = 1,000 cached positions · L = P + 1 = 1,001 keys read
Parameters

117,440,512 parameters per instance, across its learned components

Exact per-instance accounting
ComponentCalculationParameters
Mix and project117,440,512 across its components117,440,512
Per-instance total117,440,512

Across 58 independent MoE blocks: 117,440,512×58=6,811,549,696117{,}440{,}512 \times 58 = 6{,}811{,}549{,}696 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

The reference takes this path when a mask is passed, for more than one position (model.py 574–589); a single decoded token scores the cached latent directly.

Codemodel.py 590–608
model.py 590–606
        else:                   # MQA decode
            if self.dequant_wkv_b is None and self.wkv_b.scale is not None:
                self.dequant_wkv_b = weight_dequant(self.wkv_b.weight, self.wkv_b.scale)
            wkv_b = self.wkv_b.weight if self.dequant_wkv_b is None else self.dequant_wkv_b
            wkv_b = wkv_b.view(self.n_local_heads, -1, self.kv_lora_rank)
            q_nope = torch.einsum("bshd,hdc->bshc", q_nope, wkv_b[:, :self.qk_nope_head_dim])
            scores = (torch.einsum("bshc,btc->bsht", q_nope, self.kv_cache[:bsz, :end_pos]) +
                      torch.einsum("bshr,btr->bsht", q_pe, self.pe_cache[:bsz, :end_pos])) * self.softmax_scale

            # indexer
            topk_indices = self.indexer(x, qr, start_pos, freqs_cis, mask)
            index_mask = torch.full((bsz, 1, end_pos), float("-inf"), device=x.device).scatter_(-1, topk_indices, 0)
            scores += index_mask.unsqueeze(2)

            scores = scores.softmax(dim=-1)
            x = torch.einsum("bsht,btc->bshc", scores, self.kv_cache[:bsz, :end_pos])
            x = torch.einsum("bshc,hdc->bshd", x, wkv_b[:, -self.v_head_dim:])
model.py 607–608
        x = self.wo(x.flatten(2))
        return x
Sources2

Direct evidence

When decoding one token, the implementation absorbs the key–value up-projection into queries and outputs and attends over the cached latent directly.

mla-decode · deepseek-ai/DeepSeek-V3.2-Exp / inference/model.py
Pinned revision 87e509a2e5a1 ↗ · lines 590–606

Read code excerpt
        else:                   # MQA decode
            if self.dequant_wkv_b is None and self.wkv_b.scale is not None:
                self.dequant_wkv_b = weight_dequant(self.wkv_b.weight, self.wkv_b.scale)
            wkv_b = self.wkv_b.weight if self.dequant_wkv_b is None else self.dequant_wkv_b
            wkv_b = wkv_b.view(self.n_local_heads, -1, self.kv_lora_rank)
            q_nope = torch.einsum("bshd,hdc->bshc", q_nope, wkv_b[:, :self.qk_nope_head_dim])
            scores = (torch.einsum("bshc,btc->bsht", q_nope, self.kv_cache[:bsz, :end_pos]) +
                      torch.einsum("bshr,btr->bsht", q_pe, self.pe_cache[:bsz, :end_pos])) * self.softmax_scale

            # indexer
            topk_indices = self.indexer(x, qr, start_pos, freqs_cis, mask)
            index_mask = torch.full((bsz, 1, end_pos), float("-inf"), device=x.device).scatter_(-1, topk_indices, 0)
            scores += index_mask.unsqueeze(2)

            scores = scores.softmax(dim=-1)
            x = torch.einsum("bsht,btc->bshc", scores, self.kv_cache[:bsz, :end_pos])
            x = torch.einsum("bshc,hdc->bshd", x, wkv_b[:, -self.v_head_dim:])

Direct evidence

Head outputs are flattened and projected back to the model width.

mla-output · deepseek-ai/DeepSeek-V3.2-Exp / inference/model.py
Pinned revision 87e509a2e5a1 ↗ · lines 607–608

Read code excerpt
        x = self.wo(x.flatten(2))
        return x