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Optimize cpu sketch allreduce for sparse data. (#6009)

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* Bypass RABIT serialization reducer and use custom allgather based merging.
This commit is contained in:
Jiaming Yuan
2020-08-19 10:03:45 +08:00
committed by GitHub
parent 90355b4f00
commit 29b7fea572
10 changed files with 357 additions and 87 deletions
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26
src/common/quantile.h
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@@ -166,6 +166,16 @@ struct WQSummary {
* \param src source sketch
*/
inline void CopyFrom(const WQSummary &src) {
if (!src.data) {
CHECK_EQ(src.size, 0);
size = 0;
return;
}
if (!data) {
CHECK_EQ(this->size, 0);
CHECK_EQ(src.size, 0);
return;
}
size = src.size;
std::memcpy(data, src.data, sizeof(Entry) * size);
}
@@ -721,6 +731,14 @@ class HostSketchContainer {
return use_group_ind;
}
static std::vector<bst_row_t> CalcColumnSize(SparsePage const &page,
bst_feature_t const n_columns,
size_t const nthreads);
static std::vector<bst_feature_t> LoadBalance(SparsePage const &page,
bst_feature_t n_columns,
size_t const nthreads);
static uint32_t SearchGroupIndFromRow(std::vector<bst_uint> const &group_ptr,
size_t const base_rowid) {
CHECK_LT(base_rowid, group_ptr.back())
@@ -730,6 +748,14 @@ class HostSketchContainer {
group_ptr.cbegin() - 1;
return group_ind;
}
// Gather sketches from all workers.
void GatherSketchInfo(std::vector<WQSketch::SummaryContainer> const &reduced,
std::vector<bst_row_t> *p_worker_segments,
std::vector<bst_row_t> *p_sketches_scan,
std::vector<WQSketch::Entry> *p_global_sketches);
// Merge sketches from all workers.
void AllReduce(std::vector<WQSketch::SummaryContainer> *p_reduced,
std::vector<int32_t>* p_num_cuts);
/* \brief Push a CSR matrix. */
void PushRowPage(SparsePage const& page, MetaInfo const& info);