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top-k sort speedup #5085

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top-k sort speedup #5085

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84aa889
top-k sort speedup
cmp-nct Jan 22, 2024
73fbbd1
Update llama.cpp
cmp-nct Jan 22, 2024
c0cfcaf
Update llama.cpp
cmp-nct Jan 23, 2024
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10 changes: 8 additions & 2 deletions llama.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8001,10 +8001,16 @@ void llama_sample_top_k(struct llama_context * ctx, llama_token_data_array * can
auto comp = [](const llama_token_data & a, const llama_token_data & b) {
return a.logit > b.logit;
};
if (k == (int) candidates->size) {
if (k >= (int) (3*candidates->size /4)) {
std::sort(candidates->data, candidates->data + candidates->size, comp);
} else {
std::partial_sort(candidates->data, candidates->data + k, candidates->data + candidates->size, comp);
if (k > 3000) {
// this needs a closer look, tests on multiple platforms. On Intel I7 13th gen with VC compilers the performance is equal at ~2500 top-k. Before that partial_sort is faster.
std::nth_element(candidates->data, candidates->data + k, candidates->data + candidates->size, comp); // separate stack to top-k
std::sort(candidates->data, candidates->data + k, comp); // Sort the top-k stack
} else {
std::partial_sort(candidates->data, candidates->data + k, candidates->data + candidates->size, comp);
}
}
candidates->sorted = true;
}
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