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Cap n_outputs_max on MTP draft contexts #2287

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Merged
LostRuins merged 1 commit into from
Jun 25, 2026
Merged

Cap n_outputs_max on MTP draft contexts #2287

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2 changes: 2 additions & 0 deletions gpttype_adapter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -597,6 +597,7 @@ static size_t estimate_draft_autofit_tax_mb(
{
draft_ctx_params.ctx_type = LLAMA_CONTEXT_TYPE_MTP;
draft_ctx_params.n_rs_seq = speculative_chunk_amt;
draft_ctx_params.n_outputs_max = base_ctx_params.n_seq_max; //match the real MTP draft context (see speculative_decoding_setup) so the autofit tax doesn't over-reserve the draft compute buffer at n_batch*n_vocab (~2GB on large-vocab models like Gemma)
measure_model_bytes = has_draft_model;
}

Expand Down Expand Up @@ -950,6 +951,7 @@ static void speculative_decoding_setup(std::string spec_model_filename, llama_co
draft_ctx_params.ctx_type = LLAMA_CONTEXT_TYPE_MTP;
draft_ctx_params.ctx_other = main_ctx;
draft_ctx_params.n_rs_seq = speculative_chunk_amt;
draft_ctx_params.n_outputs_max = base_ctx_params.n_seq_max; //draft-mtp generates tokens autoregressively (1 output per sequence per decode, looped up to n_max); cap outputs at n_seq instead of letting it default to n_batch, which sized the draft sampling buffer at n_batch*n_vocab (~2GB on large-vocab models like Gemma)
}
draft_ctx = llama_init_from_model(draftmodel, draft_ctx_params);
if(draft_ctx == NULL)
Expand Down