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Improved InitSampling function speed by 2.12 times (#6410)

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* Improved InitSampling function speed by 2.12 times

* Added explicit conversion
This commit is contained in:
Igor Rukhovich 2020-12-16 07:59:24 +03:00 committed by GitHub
parent 3c3f026ec1
commit 5c8ccf4455
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1 changed files with 4 additions and 3 deletions
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7
src/tree/updater_quantile_hist.cc
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@ -695,17 +695,18 @@ void QuantileHistMaker::Builder<GradientSumT>::InitSampling(const std::vector<Gr
r = rnd;
}
const size_t discard_size = info.num_row_ / nthread;
auto upper_border = static_cast<float>(std::numeric_limits<uint32_t>::max());
uint32_t coin_flip_border = static_cast<uint32_t>(upper_border * param_.subsample);
#pragma omp parallel num_threads(nthread)
{
const size_t tid = omp_get_thread_num();
const size_t ibegin = tid * discard_size;
const size_t iend = (tid == (nthread - 1)) ?
info.num_row_ : ibegin + discard_size;
std::bernoulli_distribution coin_flip(param_.subsample);
rnds[tid].discard(2*discard_size * tid);
rnds[tid].discard(discard_size * tid);
for (size_t i = ibegin; i < iend; ++i) {
if (gpair[i].GetHess() >= 0.0f && coin_flip(rnds[tid])) {
if (gpair[i].GetHess() >= 0.0f && rnds[tid]() < coin_flip_border) {
p_row_indices[ibegin + row_offsets[tid]++] = i;
}
}