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spec: support spec-draft-p-min in DFlash #25246

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Merged
ruixiang63 merged 3 commits into from
Jul 3, 2026
Merged

spec: support spec-draft-p-min in DFlash #25246

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0e1cdb1
spec: support spec-draft-p-min in DFlash
ruixiang63 Jul 2, 2026
0a1db92
dflash: add n_min guard
ruixiang63 Jul 2, 2026
f592733
dflash: guard both n_min and n_max
ruixiang63 Jul 3, 2026
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19 changes: 14 additions & 5 deletions common/speculative.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -955,10 +955,11 @@ struct common_speculative_impl_draft_dflash : public common_speculative_impl {
LOG_INF("%s: - block_size=%d, mask_token_id=%d, n_extract=%u\n", __func__, block_size, mask_token_id, target_layer_ids_n);

// DFlash input is [id_last, <mask> * (block_size-1)], so it can draft at most block_size-1 tokens per step
if (this->params.n_max > block_size - 1) {
LOG_WRN("%s: requested draft size %d exceeds the trained DFlash block size %d -- clamping to %d draft tokens per step\n",
__func__, this->params.n_max, block_size - 1, block_size - 1);
this->params.n_max = block_size - 1;
if (this->params.n_max > block_size - 1 || this->params.n_min > block_size - 1) {
LOG_WRN("%s: requested draft size (n_max=%d, n_min=%d) exceeds the trained DFlash block size %d -- clamping to %d\n",
__func__, this->params.n_max, this->params.n_min, block_size, block_size - 1);
this->params.n_max = std::min(this->params.n_max, block_size - 1);
this->params.n_min = std::min(this->params.n_min, block_size - 1);
}

batch = llama_batch_init(llama_n_batch(ctx_dft), 0, n_seq);
Expand All @@ -968,7 +969,7 @@ struct common_speculative_impl_draft_dflash : public common_speculative_impl {
for (auto & s : smpls) {
common_params_sampling sparams;
sparams.no_perf = false;
sparams.top_k = 1;
sparams.top_k = 10;
sparams.samplers = { COMMON_SAMPLER_TYPE_TOP_K };
s.reset(common_sampler_init(model_dft, sparams));
}
Expand Down Expand Up @@ -1173,10 +1174,18 @@ struct common_speculative_impl_draft_dflash : public common_speculative_impl {

const llama_token id = cur_p->data[0].id;

if (cur_p->data[0].p < params.p_min) {
break;
}

common_sampler_accept(smpl, id, true);

result.push_back(id);
}

if (result.size() < (size_t) params.n_min) {
result.clear();
}
}
}

Expand Down