xgboost/tests/cpp/tree/test_gpu_hist.cu
Rory Mitchell 93f9ce9ef9
Single precision histograms on GPU (#3965)
* Allow single precision histogram summation in gpu_hist

* Add python test, reduce run-time of gpu_hist tests

* Update documentation
2018-12-10 10:55:30 +13:00

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/*!
* Copyright 2017-2018 XGBoost contributors
*/
#include <thrust/device_vector.h>
#include <xgboost/base.h>
#include <random>
#include "../helpers.h"
#include "gtest/gtest.h"
#include "../../../src/data/sparse_page_source.h"
#include "../../../src/gbm/gbtree_model.h"
#include "../../../src/tree/updater_gpu_hist.cu"
#include "../../../src/tree/updater_gpu_common.cuh"
#include "../../../src/common/common.h"
namespace xgboost {
namespace tree {
template <typename GradientSumT>
void BuildGidx(DeviceShard<GradientSumT>* shard, int n_rows, int n_cols,
bst_float sparsity=0) {
auto dmat = CreateDMatrix(n_rows, n_cols, sparsity, 3);
const SparsePage& batch = *(*dmat)->GetRowBatches().begin();
common::HistCutMatrix cmat;
cmat.row_ptr = {0, 3, 6, 9, 12, 15, 18, 21, 24};
cmat.min_val = {0.1f, 0.2f, 0.3f, 0.1f, 0.2f, 0.3f, 0.2f, 0.2f};
// 24 cut fields, 3 cut fields for each feature (column).
cmat.cut = {0.30f, 0.67f, 1.64f,
0.32f, 0.77f, 1.95f,
0.29f, 0.70f, 1.80f,
0.32f, 0.75f, 1.85f,
0.18f, 0.59f, 1.69f,
0.25f, 0.74f, 2.00f,
0.26f, 0.74f, 1.98f,
0.26f, 0.71f, 1.83f};
shard->InitRowPtrs(batch);
shard->InitCompressedData(cmat, batch);
delete dmat;
}
TEST(GpuHist, BuildGidxDense) {
int const n_rows = 16, n_cols = 8;
TrainParam param;
param.max_depth = 1;
param.n_gpus = 1;
param.max_leaves = 0;
DeviceShard<GradientPairPrecise> shard(0, 0, n_rows, param);
BuildGidx(&shard, n_rows, n_cols);
std::vector<common::CompressedByteT> h_gidx_buffer;
h_gidx_buffer = shard.gidx_buffer.AsVector();
common::CompressedIterator<uint32_t> gidx(h_gidx_buffer.data(), 25);
ASSERT_EQ(shard.row_stride, n_cols);
std::vector<uint32_t> solution = {
0, 3, 8, 9, 14, 17, 20, 21,
0, 4, 7, 10, 14, 16, 19, 22,
1, 3, 7, 11, 14, 15, 19, 21,
2, 3, 7, 9, 13, 16, 20, 22,
2, 3, 6, 9, 12, 16, 20, 21,
1, 5, 6, 10, 13, 16, 20, 21,
2, 5, 8, 9, 13, 17, 19, 22,
2, 4, 6, 10, 14, 17, 19, 21,
2, 5, 7, 9, 13, 16, 19, 22,
0, 3, 8, 10, 12, 16, 19, 22,
1, 3, 7, 10, 13, 16, 19, 21,
1, 3, 8, 10, 13, 17, 20, 22,
2, 4, 6, 9, 14, 15, 19, 22,
1, 4, 6, 9, 13, 16, 19, 21,
2, 4, 8, 10, 14, 15, 19, 22,
1, 4, 7, 10, 14, 16, 19, 21,
};
for (size_t i = 0; i < n_rows * n_cols; ++i) {
ASSERT_EQ(solution[i], gidx[i]);
}
}
TEST(GpuHist, BuildGidxSparse) {
int const n_rows = 16, n_cols = 8;
TrainParam param;
param.max_depth = 1;
param.n_gpus = 1;
param.max_leaves = 0;
DeviceShard<GradientPairPrecise> shard(0, 0, n_rows, param);
BuildGidx(&shard, n_rows, n_cols, 0.9f);
std::vector<common::CompressedByteT> h_gidx_buffer;
h_gidx_buffer = shard.gidx_buffer.AsVector();
common::CompressedIterator<uint32_t> gidx(h_gidx_buffer.data(), 25);
ASSERT_LE(shard.row_stride, 3);
// row_stride = 3, 16 rows, 48 entries for ELLPack
std::vector<uint32_t> solution = {
15, 24, 24, 0, 24, 24, 24, 24, 24, 24, 24, 24, 20, 24, 24, 24,
24, 24, 24, 24, 24, 5, 24, 24, 0, 16, 24, 15, 24, 24, 24, 24,
24, 7, 14, 16, 4, 24, 24, 24, 24, 24, 9, 24, 24, 1, 24, 24
};
for (size_t i = 0; i < n_rows * shard.row_stride; ++i) {
ASSERT_EQ(solution[i], gidx[i]);
}
}
std::vector<GradientPairPrecise> GetHostHistGpair() {
// 24 bins, 3 bins for each feature (column).
std::vector<GradientPairPrecise> hist_gpair = {
{0.8314f, 0.7147f}, {1.7989f, 3.7312f}, {3.3846f, 3.4598f},
{2.9277f, 3.5886f}, {1.8429f, 2.4152f}, {1.2443f, 1.9019f},
{1.6380f, 2.9174f}, {1.5657f, 2.5107f}, {2.8111f, 2.4776f},
{2.1322f, 3.0651f}, {3.2927f, 3.8540f}, {0.5899f, 0.9866f},
{1.5185f, 1.6263f}, {2.0686f, 3.1844f}, {2.4278f, 3.0950f},
{1.5105f, 2.1403f}, {2.6922f, 4.2217f}, {1.8122f, 1.5437f},
{0.0000f, 0.0000f}, {4.3245f, 5.7955f}, {1.6903f, 2.1103f},
{2.4012f, 4.4754f}, {3.6136f, 3.4303f}, {0.0000f, 0.0000f}
};
return hist_gpair;
}
template <typename GradientSumT>
void TestBuildHist(GPUHistBuilderBase<GradientSumT>& builder) {
int const n_rows = 16, n_cols = 8;
TrainParam param;
param.max_depth = 6;
param.n_gpus = 1;
param.max_leaves = 0;
DeviceShard<GradientSumT> shard(0, 0, n_rows, param);
BuildGidx(&shard, n_rows, n_cols);
xgboost::SimpleLCG gen;
xgboost::SimpleRealUniformDistribution<bst_float> dist(0.0f, 1.0f);
std::vector<GradientPair> h_gpair(n_rows);
for (size_t i = 0; i < h_gpair.size(); ++i) {
bst_float grad = dist(&gen);
bst_float hess = dist(&gen);
h_gpair[i] = GradientPair(grad, hess);
}
thrust::device_vector<GradientPair> gpair (n_rows);
gpair = h_gpair;
int num_symbols = shard.n_bins + 1;
thrust::host_vector<common::CompressedByteT> h_gidx_buffer (
shard.gidx_buffer.Size());
common::CompressedByteT* d_gidx_buffer_ptr = shard.gidx_buffer.Data();
dh::safe_cuda(cudaMemcpy(h_gidx_buffer.data(), d_gidx_buffer_ptr,
sizeof(common::CompressedByteT) * shard.gidx_buffer.Size(),
cudaMemcpyDeviceToHost));
auto gidx = common::CompressedIterator<uint32_t>(h_gidx_buffer.data(),
num_symbols);
shard.ridx_segments.resize(1);
shard.ridx_segments[0] = Segment(0, n_rows);
shard.hist.AllocateHistogram(0);
shard.gpair.copy(gpair.begin(), gpair.end());
thrust::sequence(shard.ridx.CurrentDVec().tbegin(),
shard.ridx.CurrentDVec().tend());
builder.Build(&shard, 0);
DeviceHistogram<GradientSumT> d_hist = shard.hist;
auto node_histogram = d_hist.GetNodeHistogram(0);
// d_hist.data stored in float, not gradient pair
thrust::host_vector<GradientSumT> h_result (d_hist.data.size()/2);
size_t data_size =
sizeof(GradientSumT) /
(sizeof(GradientSumT) / sizeof(typename GradientSumT::ValueT));
data_size *= d_hist.data.size();
dh::safe_cuda(cudaMemcpy(h_result.data(), node_histogram.data(), data_size,
cudaMemcpyDeviceToHost));
std::vector<GradientPairPrecise> solution = GetHostHistGpair();
std::cout << std::fixed;
for (size_t i = 0; i < h_result.size(); ++i) {
EXPECT_NEAR(h_result[i].GetGrad(), solution[i].GetGrad(), 0.01f);
EXPECT_NEAR(h_result[i].GetHess(), solution[i].GetHess(), 0.01f);
}
}
TEST(GpuHist, BuildHistGlobalMem) {
GlobalMemHistBuilder<GradientPairPrecise> double_builder;
TestBuildHist(double_builder);
GlobalMemHistBuilder<GradientPair> float_builder;
TestBuildHist(float_builder);
}
TEST(GpuHist, BuildHistSharedMem) {
SharedMemHistBuilder<GradientPairPrecise> double_builder;
TestBuildHist(double_builder);
SharedMemHistBuilder<GradientPair> float_builder;
TestBuildHist(float_builder);
}
common::HistCutMatrix GetHostCutMatrix () {
common::HistCutMatrix cmat;
cmat.row_ptr = {0, 3, 6, 9, 12, 15, 18, 21, 24};
cmat.min_val = {0.1f, 0.2f, 0.3f, 0.1f, 0.2f, 0.3f, 0.2f, 0.2f};
// 24 cut fields, 3 cut fields for each feature (column).
// Each row of the cut represents the cuts for a data column.
cmat.cut = {0.30f, 0.67f, 1.64f,
0.32f, 0.77f, 1.95f,
0.29f, 0.70f, 1.80f,
0.32f, 0.75f, 1.85f,
0.18f, 0.59f, 1.69f,
0.25f, 0.74f, 2.00f,
0.26f, 0.74f, 1.98f,
0.26f, 0.71f, 1.83f};
return cmat;
}
// TODO(trivialfis): This test is over simplified.
TEST(GpuHist, EvaluateSplits) {
constexpr int n_rows = 16;
constexpr int n_cols = 8;
TrainParam param;
param.max_depth = 1;
param.n_gpus = 1;
param.colsample_bylevel = 1;
param.colsample_bytree = 1;
param.min_child_weight = 0.01;
// Disable all parameters.
param.reg_alpha = 0.0;
param.reg_lambda = 0;
param.max_delta_step = 0.0;
for (size_t i = 0; i < n_cols; ++i) {
param.monotone_constraints.emplace_back(0);
}
int max_bins = 4;
// Initialize DeviceShard
std::unique_ptr<DeviceShard<GradientPairPrecise>> shard {new DeviceShard<GradientPairPrecise>(0, 0, n_rows, param)};
// Initialize DeviceShard::node_sum_gradients
shard->node_sum_gradients = {{6.4f, 12.8f}};
// Initialize DeviceShard::cut
common::HistCutMatrix cmat = GetHostCutMatrix();
// Copy cut matrix to device.
DeviceShard<GradientPairPrecise>::DeviceHistCutMatrix cut;
shard->ba.Allocate(0, true,
&(shard->cut_.feature_segments), cmat.row_ptr.size(),
&(shard->cut_.min_fvalue), cmat.min_val.size(),
&(shard->cut_.gidx_fvalue_map), 24,
&(shard->monotone_constraints), n_cols);
shard->cut_.feature_segments.copy(cmat.row_ptr.begin(), cmat.row_ptr.end());
shard->cut_.gidx_fvalue_map.copy(cmat.cut.begin(), cmat.cut.end());
shard->monotone_constraints.copy(param.monotone_constraints.begin(),
param.monotone_constraints.end());
// Initialize DeviceShard::hist
shard->hist.Init(0, (max_bins - 1) * n_cols);
shard->hist.AllocateHistogram(0);
// Each row of hist_gpair represents gpairs for one feature.
// Each entry represents a bin.
std::vector<GradientPairPrecise> hist_gpair = GetHostHistGpair();
std::vector<bst_float> hist;
for (auto pair : hist_gpair) {
hist.push_back(pair.GetGrad());
hist.push_back(pair.GetHess());
}
ASSERT_EQ(shard->hist.data.size(), hist.size());
thrust::copy(hist.begin(), hist.end(),
shard->hist.data.begin());
// Initialize GPUHistMaker
GPUHistMakerSpecialised<GradientPairPrecise> hist_maker =
GPUHistMakerSpecialised<GradientPairPrecise>();
hist_maker.param_ = param;
hist_maker.shards_.push_back(std::move(shard));
hist_maker.column_sampler_.Init(n_cols,
param.colsample_bylevel,
param.colsample_bytree,
false);
RegTree tree;
tree.InitModel();
MetaInfo info;
info.num_row_ = n_rows;
info.num_col_ = n_cols;
hist_maker.info_ = &info;
hist_maker.node_value_constraints_.resize(1);
hist_maker.node_value_constraints_[0].lower_bound = -1.0;
hist_maker.node_value_constraints_[0].upper_bound = 1.0;
DeviceSplitCandidate res =
hist_maker.EvaluateSplit(0, &tree);
ASSERT_EQ(res.findex, 7);
ASSERT_NEAR(res.fvalue, 0.26, xgboost::kRtEps);
}
TEST(GpuHist, ApplySplit) {
GPUHistMakerSpecialised<GradientPairPrecise> hist_maker =
GPUHistMakerSpecialised<GradientPairPrecise>();
int constexpr nid = 0;
int constexpr n_rows = 16;
int constexpr n_cols = 8;
TrainParam param;
param.silent = true;
// Initialize shard
for (size_t i = 0; i < n_cols; ++i) {
param.monotone_constraints.emplace_back(0);
}
hist_maker.shards_.resize(1);
hist_maker.shards_[0].reset(new DeviceShard<GradientPairPrecise>(0, 0, n_rows, param));
auto& shard = hist_maker.shards_.at(0);
shard->ridx_segments.resize(3); // 3 nodes.
shard->node_sum_gradients.resize(3);
shard->ridx_segments[0] = Segment(0, n_rows);
shard->ba.Allocate(0, true, &(shard->ridx), n_rows,
&(shard->position), n_rows);
shard->row_stride = n_cols;
thrust::sequence(shard->ridx.CurrentDVec().tbegin(),
shard->ridx.CurrentDVec().tend());
// Initialize GPUHistMaker
hist_maker.param_ = param;
RegTree tree;
tree.InitModel();
DeviceSplitCandidate candidate;
candidate.Update(2, kLeftDir,
0.59, 4, // fvalue has to be equal to one of the cut field
GradientPair(8.2, 2.8), GradientPair(6.3, 3.6),
GPUTrainingParam(param));
GPUHistMakerSpecialised<GradientPairPrecise>::ExpandEntry candidate_entry {0, 0, candidate, 0};
candidate_entry.nid = nid;
auto const& nodes = tree.GetNodes();
size_t n_nodes = nodes.size();
// Used to get bin_id in update position.
common::HistCutMatrix cmat = GetHostCutMatrix();
hist_maker.hmat_ = cmat;
MetaInfo info;
info.num_row_ = n_rows;
info.num_col_ = n_cols;
info.num_nonzero_ = n_rows * n_cols; // Dense
// Initialize gidx
int n_bins = 24;
int row_stride = n_cols;
int num_symbols = n_bins + 1;
size_t compressed_size_bytes =
common::CompressedBufferWriter::CalculateBufferSize(
row_stride * n_rows, num_symbols);
shard->ba.Allocate(0, param.silent,
&(shard->gidx_buffer), compressed_size_bytes);
common::CompressedBufferWriter wr(num_symbols);
std::vector<int> h_gidx (n_rows * row_stride);
std::iota(h_gidx.begin(), h_gidx.end(), 0);
std::vector<common::CompressedByteT> h_gidx_compressed (compressed_size_bytes);
wr.Write(h_gidx_compressed.data(), h_gidx.begin(), h_gidx.end());
shard->gidx_buffer.copy(h_gidx_compressed.begin(), h_gidx_compressed.end());
shard->gidx = common::CompressedIterator<uint32_t>(
shard->gidx_buffer.Data(), num_symbols);
hist_maker.info_ = &info;
hist_maker.ApplySplit(candidate_entry, &tree);
hist_maker.UpdatePosition(candidate_entry, &tree);
ASSERT_FALSE(tree[nid].IsLeaf());
int left_nidx = tree[nid].LeftChild();
int right_nidx = tree[nid].RightChild();
ASSERT_EQ(shard->ridx_segments[left_nidx].begin, 0);
ASSERT_EQ(shard->ridx_segments[left_nidx].end, 6);
ASSERT_EQ(shard->ridx_segments[right_nidx].begin, 6);
ASSERT_EQ(shard->ridx_segments[right_nidx].end, 16);
}
void TestSortPosition(const std::vector<int>& position_in, int left_idx,
int right_idx) {
int left_count = std::count(position_in.begin(), position_in.end(), left_idx);
thrust::device_vector<int> position = position_in;
thrust::device_vector<int> position_out(position.size());
thrust::device_vector<bst_uint> ridx(position.size());
thrust::sequence(ridx.begin(), ridx.end());
thrust::device_vector<bst_uint> ridx_out(ridx.size());
dh::CubMemory tmp;
SortPosition(
&tmp, common::Span<int>(position.data().get(), position.size()),
common::Span<int>(position_out.data().get(), position_out.size()),
common::Span<bst_uint>(ridx.data().get(), ridx.size()),
common::Span<bst_uint>(ridx_out.data().get(), ridx_out.size()), left_idx,
right_idx, left_count);
thrust::host_vector<int> position_result = position_out;
thrust::host_vector<int> ridx_result = ridx_out;
// Check position is sorted
EXPECT_TRUE(std::is_sorted(position_result.begin(), position_result.end()));
// Check row indices are sorted inside left and right segment
EXPECT_TRUE(
std::is_sorted(ridx_result.begin(), ridx_result.begin() + left_count));
EXPECT_TRUE(
std::is_sorted(ridx_result.begin() + left_count, ridx_result.end()));
// Check key value pairs are the same
for (auto i = 0ull; i < ridx_result.size(); i++) {
EXPECT_EQ(position_result[i], position_in[ridx_result[i]]);
}
}
TEST(GpuHist, SortPosition) {
TestSortPosition({1, 2, 1, 2, 1}, 1, 2);
TestSortPosition({1, 1, 1, 1}, 1, 2);
TestSortPosition({2, 2, 2, 2}, 1, 2);
TestSortPosition({1, 2, 1, 2, 3}, 1, 2);
}
} // namespace tree
} // namespace xgboost