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Small refactor for hist builder. (#8698)

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- Use span instead of vector as parameter. No perf change as the builder work on pointer.
- Use const pointer for reg tree.
This commit is contained in:
Jiaming Yuan
2023-01-30 14:06:41 +08:00
committed by GitHub
parent 8af98e30fc
commit 21a28f2cc5
3 changed files with 95 additions and 120 deletions
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161
src/tree/hist/histogram.h
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@@ -1,5 +1,5 @@
/*!
* Copyright 2021-2022 by XGBoost Contributors
/**
* Copyright 2021-2023 by XGBoost Contributors
*/
#ifndef XGBOOST_TREE_HIST_HISTOGRAM_H_
#define XGBOOST_TREE_HIST_HISTOGRAM_H_
@@ -59,15 +59,14 @@ class HistogramBuilder {
GHistIndexMatrix const &gidx,
std::vector<ExpandEntry> const &nodes_for_explicit_hist_build,
common::RowSetCollection const &row_set_collection,
const std::vector<GradientPair> &gpair_h,
bool force_read_by_column) {
common::Span<GradientPair const> gpair_h, bool force_read_by_column) {
const size_t n_nodes = nodes_for_explicit_hist_build.size();
CHECK_GT(n_nodes, 0);
std::vector<common::GHistRow> target_hists(n_nodes);
for (size_t i = 0; i < n_nodes; ++i) {
const int32_t nid = nodes_for_explicit_hist_build[i].nid;
target_hists[i] = hist_[nid];
auto const nidx = nodes_for_explicit_hist_build[i].nid;
target_hists[i] = hist_[nidx];
}
if (page_idx == 0) {
// FIXME(jiamingy): Handle different size of space. Right now we use the maximum
@@ -93,46 +92,37 @@ class HistogramBuilder {
});
}
void
AddHistRows(int *starting_index, int *sync_count,
std::vector<ExpandEntry> const &nodes_for_explicit_hist_build,
std::vector<ExpandEntry> const &nodes_for_subtraction_trick,
RegTree *p_tree) {
void AddHistRows(int *starting_index, int *sync_count,
std::vector<ExpandEntry> const &nodes_for_explicit_hist_build,
std::vector<ExpandEntry> const &nodes_for_subtraction_trick,
RegTree const *p_tree) {
if (is_distributed_) {
this->AddHistRowsDistributed(starting_index, sync_count,
nodes_for_explicit_hist_build,
this->AddHistRowsDistributed(starting_index, sync_count, nodes_for_explicit_hist_build,
nodes_for_subtraction_trick, p_tree);
} else {
this->AddHistRowsLocal(starting_index, sync_count,
nodes_for_explicit_hist_build,
this->AddHistRowsLocal(starting_index, sync_count, nodes_for_explicit_hist_build,
nodes_for_subtraction_trick);
}
}
/** Main entry point of this class, build histogram for tree nodes. */
void BuildHist(size_t page_id, common::BlockedSpace2d space, GHistIndexMatrix const &gidx,
RegTree *p_tree, common::RowSetCollection const &row_set_collection,
RegTree const *p_tree, common::RowSetCollection const &row_set_collection,
std::vector<ExpandEntry> const &nodes_for_explicit_hist_build,
std::vector<ExpandEntry> const &nodes_for_subtraction_trick,
std::vector<GradientPair> const &gpair,
bool force_read_by_column = false) {
common::Span<GradientPair const> gpair, bool force_read_by_column = false) {
int starting_index = std::numeric_limits<int>::max();
int sync_count = 0;
if (page_id == 0) {
this->AddHistRows(&starting_index, &sync_count,
nodes_for_explicit_hist_build,
this->AddHistRows(&starting_index, &sync_count, nodes_for_explicit_hist_build,
nodes_for_subtraction_trick, p_tree);
}
if (gidx.IsDense()) {
this->BuildLocalHistograms<false>(page_id, space, gidx,
nodes_for_explicit_hist_build,
row_set_collection, gpair,
force_read_by_column);
this->BuildLocalHistograms<false>(page_id, space, gidx, nodes_for_explicit_hist_build,
row_set_collection, gpair, force_read_by_column);
} else {
this->BuildLocalHistograms<true>(page_id, space, gidx,
nodes_for_explicit_hist_build,
row_set_collection, gpair,
force_read_by_column);
this->BuildLocalHistograms<true>(page_id, space, gidx, nodes_for_explicit_hist_build,
row_set_collection, gpair, force_read_by_column);
}
CHECK_GE(n_batches_, 1);
@@ -153,8 +143,7 @@ class HistogramBuilder {
common::RowSetCollection const &row_set_collection,
std::vector<ExpandEntry> const &nodes_for_explicit_hist_build,
std::vector<ExpandEntry> const &nodes_for_subtraction_trick,
std::vector<GradientPair> const &gpair,
bool force_read_by_column = false) {
common::Span<GradientPair const> gpair, bool force_read_by_column = false) {
const size_t n_nodes = nodes_for_explicit_hist_build.size();
// create space of size (# rows in each node)
common::BlockedSpace2d space(
@@ -164,83 +153,72 @@ class HistogramBuilder {
return row_set_collection[nidx].Size();
},
256);
this->BuildHist(page_id, space, gidx, p_tree, row_set_collection,
nodes_for_explicit_hist_build, nodes_for_subtraction_trick,
gpair, force_read_by_column);
this->BuildHist(page_id, space, gidx, p_tree, row_set_collection, nodes_for_explicit_hist_build,
nodes_for_subtraction_trick, gpair, force_read_by_column);
}
void SyncHistogramDistributed(
RegTree *p_tree,
std::vector<ExpandEntry> const &nodes_for_explicit_hist_build,
std::vector<ExpandEntry> const &nodes_for_subtraction_trick,
int starting_index, int sync_count) {
void SyncHistogramDistributed(RegTree const *p_tree,
std::vector<ExpandEntry> const &nodes_for_explicit_hist_build,
std::vector<ExpandEntry> const &nodes_for_subtraction_trick,
int starting_index, int sync_count) {
const size_t nbins = builder_.GetNumBins();
common::BlockedSpace2d space(
nodes_for_explicit_hist_build.size(), [&](size_t) { return nbins; },
1024);
common::ParallelFor2d(
space, n_threads_, [&](size_t node, common::Range1d r) {
const auto &entry = nodes_for_explicit_hist_build[node];
auto this_hist = this->hist_[entry.nid];
// Merging histograms from each thread into once
buffer_.ReduceHist(node, r.begin(), r.end());
// Store posible parent node
auto this_local = hist_local_worker_[entry.nid];
common::CopyHist(this_local, this_hist, r.begin(), r.end());
nodes_for_explicit_hist_build.size(), [&](size_t) { return nbins; }, 1024);
common::ParallelFor2d(space, n_threads_, [&](size_t node, common::Range1d r) {
const auto &entry = nodes_for_explicit_hist_build[node];
auto this_hist = this->hist_[entry.nid];
// Merging histograms from each thread into once
buffer_.ReduceHist(node, r.begin(), r.end());
// Store posible parent node
auto this_local = hist_local_worker_[entry.nid];
common::CopyHist(this_local, this_hist, r.begin(), r.end());
if (!(*p_tree)[entry.nid].IsRoot()) {
const size_t parent_id = (*p_tree)[entry.nid].Parent();
const int subtraction_node_id =
nodes_for_subtraction_trick[node].nid;
auto parent_hist = this->hist_local_worker_[parent_id];
auto sibling_hist = this->hist_[subtraction_node_id];
common::SubtractionHist(sibling_hist, parent_hist, this_hist,
r.begin(), r.end());
// Store posible parent node
auto sibling_local = hist_local_worker_[subtraction_node_id];
common::CopyHist(sibling_local, sibling_hist, r.begin(), r.end());
}
});
if (!(*p_tree)[entry.nid].IsRoot()) {
const size_t parent_id = (*p_tree)[entry.nid].Parent();
const int subtraction_node_id = nodes_for_subtraction_trick[node].nid;
auto parent_hist = this->hist_local_worker_[parent_id];
auto sibling_hist = this->hist_[subtraction_node_id];
common::SubtractionHist(sibling_hist, parent_hist, this_hist, r.begin(), r.end());
// Store posible parent node
auto sibling_local = hist_local_worker_[subtraction_node_id];
common::CopyHist(sibling_local, sibling_hist, r.begin(), r.end());
}
});
collective::Allreduce<collective::Operation::kSum>(
reinterpret_cast<double *>(this->hist_[starting_index].data()),
builder_.GetNumBins() * sync_count * 2);
ParallelSubtractionHist(space, nodes_for_explicit_hist_build,
nodes_for_subtraction_trick, p_tree);
ParallelSubtractionHist(space, nodes_for_explicit_hist_build, nodes_for_subtraction_trick,
p_tree);
common::BlockedSpace2d space2(
nodes_for_subtraction_trick.size(), [&](size_t) { return nbins; },
1024);
ParallelSubtractionHist(space2, nodes_for_subtraction_trick,
nodes_for_explicit_hist_build, p_tree);
nodes_for_subtraction_trick.size(), [&](size_t) { return nbins; }, 1024);
ParallelSubtractionHist(space2, nodes_for_subtraction_trick, nodes_for_explicit_hist_build,
p_tree);
}
void SyncHistogramLocal(RegTree *p_tree,
void SyncHistogramLocal(RegTree const *p_tree,
std::vector<ExpandEntry> const &nodes_for_explicit_hist_build,
std::vector<ExpandEntry> const &nodes_for_subtraction_trick) {
const size_t nbins = this->builder_.GetNumBins();
common::BlockedSpace2d space(
nodes_for_explicit_hist_build.size(), [&](size_t) { return nbins; },
1024);
nodes_for_explicit_hist_build.size(), [&](size_t) { return nbins; }, 1024);
common::ParallelFor2d(
space, this->n_threads_, [&](size_t node, common::Range1d r) {
const auto &entry = nodes_for_explicit_hist_build[node];
auto this_hist = this->hist_[entry.nid];
// Merging histograms from each thread into once
this->buffer_.ReduceHist(node, r.begin(), r.end());
common::ParallelFor2d(space, this->n_threads_, [&](size_t node, common::Range1d r) {
const auto &entry = nodes_for_explicit_hist_build[node];
auto this_hist = this->hist_[entry.nid];
// Merging histograms from each thread into once
this->buffer_.ReduceHist(node, r.begin(), r.end());
if (!(*p_tree)[entry.nid].IsRoot()) {
const size_t parent_id = (*p_tree)[entry.nid].Parent();
const int subtraction_node_id =
nodes_for_subtraction_trick[node].nid;
auto parent_hist = this->hist_[parent_id];
auto sibling_hist = this->hist_[subtraction_node_id];
common::SubtractionHist(sibling_hist, parent_hist, this_hist,
r.begin(), r.end());
}
});
if (!(*p_tree)[entry.nid].IsRoot()) {
auto const parent_id = (*p_tree)[entry.nid].Parent();
auto const subtraction_node_id = nodes_for_subtraction_trick[node].nid;
auto parent_hist = this->hist_[parent_id];
auto sibling_hist = this->hist_[subtraction_node_id];
common::SubtractionHist(sibling_hist, parent_hist, this_hist, r.begin(), r.end());
}
});
}
public:
@@ -289,11 +267,10 @@ class HistogramBuilder {
this->hist_.AllocateAllData();
}
void AddHistRowsDistributed(
int *starting_index, int *sync_count,
std::vector<ExpandEntry> const &nodes_for_explicit_hist_build,
std::vector<ExpandEntry> const &nodes_for_subtraction_trick,
RegTree *p_tree) {
void AddHistRowsDistributed(int *starting_index, int *sync_count,
std::vector<ExpandEntry> const &nodes_for_explicit_hist_build,
std::vector<ExpandEntry> const &nodes_for_subtraction_trick,
RegTree const *p_tree) {
const size_t explicit_size = nodes_for_explicit_hist_build.size();
const size_t subtaction_size = nodes_for_subtraction_trick.size();
std::vector<int> merged_node_ids(explicit_size + subtaction_size);