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Implement devices to devices reshard. (#3721)

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* Force clearing device memory before Reshard.
* Remove calculating row_segments for gpu_hist and gpu_sketch.
* Guard against changing device.
This commit is contained in:
trivialfis 2018-09-28 17:40:23 +12:00 committed by Rory Mitchell
parent 0b7fd74138
commit 5a7f7e7d49
11 changed files with 179 additions and 96 deletions
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2
src/common/common.cu
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@ -8,6 +8,8 @@ namespace xgboost {
int AllVisibleImpl::AllVisible() {
int n_visgpus = 0;
try {
// When compiled with CUDA but running on CPU only device,
// cudaGetDeviceCount will fail.
dh::safe_cuda(cudaGetDeviceCount(&n_visgpus));
} catch(const std::exception& e) {
return 0;

87
src/common/device_helpers.cuh
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@ -110,7 +110,7 @@ inline void CheckComputeCapability() {
std::ostringstream oss;
oss << "CUDA Capability Major/Minor version number: " << prop.major << "."
<< prop.minor << " is insufficient. Need >=3.5";
int failed = prop.major < 3 || prop.major == 3 && prop.minor < 5;
int failed = prop.major < 3 || (prop.major == 3 && prop.minor < 5);
if (failed) LOG(WARNING) << oss.str() << " for device: " << d_idx;
}
}
@ -129,15 +129,10 @@ DEV_INLINE void AtomicOrByte(unsigned int* __restrict__ buffer, size_t ibyte, un
* than all elements of the array
*/
DEV_INLINE int UpperBound(const float* __restrict__ cuts, int n, float v) {
if (n == 0) {
return 0;
}
if (cuts[n - 1] <= v) {
return n;
}
if (cuts[0] > v) {
return 0;
}
if (n == 0) { return 0; }
if (cuts[n - 1] <= v) { return n; }
if (cuts[0] > v) { return 0; }
int left = 0, right = n - 1;
while (right - left > 1) {
int middle = left + (right - left) / 2;
@ -145,7 +140,7 @@ DEV_INLINE int UpperBound(const float* __restrict__ cuts, int n, float v) {
right = middle;
} else {
left = middle;
}
}
}
return right;
}
@ -184,18 +179,6 @@ T1 DivRoundUp(const T1 a, const T2 b) {
return static_cast<T1>(ceil(static_cast<double>(a) / b));
}
inline void RowSegments(size_t n_rows, size_t n_devices, std::vector<size_t>* segments) {
segments->push_back(0);
size_t row_begin = 0;
size_t shard_size = DivRoundUp(n_rows, n_devices);
for (size_t d_idx = 0; d_idx < n_devices; ++d_idx) {
size_t row_end = std::min(row_begin + shard_size, n_rows);
segments->push_back(row_end);
row_begin = row_end;
}
}
template <typename L>
__global__ void LaunchNKernel(size_t begin, size_t end, L lambda) {
for (auto i : GridStrideRange(begin, end)) {
@ -322,8 +305,8 @@ class DVec {
void copy(IterT begin, IterT end) {
safe_cuda(cudaSetDevice(this->DeviceIdx()));
if (end - begin != Size()) {
throw std::runtime_error(
"Cannot copy assign vector to DVec, sizes are different");
LOG(FATAL) << "Cannot copy assign vector to DVec, sizes are different" <<
" vector::Size(): " << end - begin << " DVec::Size(): " << Size();
}
thrust::copy(begin, end, this->tbegin());
}
@ -961,6 +944,29 @@ class AllReducer {
}
};
class SaveCudaContext {
private:
int saved_device_;
public:
template <typename Functor>
explicit SaveCudaContext (Functor func) : saved_device_{-1} {
// When compiled with CUDA but running on CPU only device,
// cudaGetDevice will fail.
try {
safe_cuda(cudaGetDevice(&saved_device_));
} catch (thrust::system::system_error & err) {
saved_device_ = -1;
}
func();
}
~SaveCudaContext() {
if (saved_device_ != -1) {
safe_cuda(cudaSetDevice(saved_device_));
}
}
};
/**
* \brief Executes some operation on each element of the input vector, using a
* single controlling thread for each element.
@ -973,10 +979,13 @@ class AllReducer {
template <typename T, typename FunctionT>
void ExecuteShards(std::vector<T> *shards, FunctionT f) {
SaveCudaContext {
[&](){
#pragma omp parallel for schedule(static, 1) if (shards->size() > 1)
for (int shard = 0; shard < shards->size(); ++shard) {
f(shards->at(shard));
}
for (int shard = 0; shard < shards->size(); ++shard) {
f(shards->at(shard));
}
}};
}
/**
@ -992,10 +1001,13 @@ void ExecuteShards(std::vector<T> *shards, FunctionT f) {
template <typename T, typename FunctionT>
void ExecuteIndexShards(std::vector<T> *shards, FunctionT f) {
SaveCudaContext {
[&](){
#pragma omp parallel for schedule(static, 1) if (shards->size() > 1)
for (int shard = 0; shard < shards->size(); ++shard) {
f(shard, shards->at(shard));
}
for (int shard = 0; shard < shards->size(); ++shard) {
f(shard, shards->at(shard));
}
}};
}
/**
@ -1011,13 +1023,16 @@ void ExecuteIndexShards(std::vector<T> *shards, FunctionT f) {
* \return A reduce_t.
*/
template <typename ReduceT,typename T, typename FunctionT>
ReduceT ReduceShards(std::vector<T> *shards, FunctionT f) {
template <typename ReduceT, typename ShardT, typename FunctionT>
ReduceT ReduceShards(std::vector<ShardT> *shards, FunctionT f) {
std::vector<ReduceT> sums(shards->size());
SaveCudaContext {
[&](){
#pragma omp parallel for schedule(static, 1) if (shards->size() > 1)
for (int shard = 0; shard < shards->size(); ++shard) {
sums[shard] = f(shards->at(shard));
}
for (int shard = 0; shard < shards->size(); ++shard) {
sums[shard] = f(shards->at(shard));
}}
};
return std::accumulate(sums.begin(), sums.end(), ReduceT());
}
} // namespace dh

1
src/common/hist_util.cc
View File

@ -17,7 +17,6 @@ namespace xgboost {
namespace common {
void HistCutMatrix::Init(DMatrix* p_fmat, uint32_t max_num_bins) {
using WXQSketch = common::WXQuantileSketch<bst_float, bst_float>;
const MetaInfo& info = p_fmat->Info();
// safe factor for better accuracy

15
src/common/hist_util.cu
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@ -347,15 +347,13 @@ struct GPUSketcher {
};
void Sketch(const SparsePage& batch, const MetaInfo& info, HistCutMatrix* hmat) {
// partition input matrix into row segments
std::vector<size_t> row_segments;
dh::RowSegments(info.num_row_, devices_.Size(), &row_segments);
// create device shards
shards_.resize(devices_.Size());
shards_.resize(dist_.Devices().Size());
dh::ExecuteIndexShards(&shards_, [&](int i, std::unique_ptr<DeviceShard>& shard) {
size_t start = dist_.ShardStart(info.num_row_, i);
size_t size = dist_.ShardSize(info.num_row_, i);
shard = std::unique_ptr<DeviceShard>
(new DeviceShard(devices_[i], row_segments[i], row_segments[i + 1], param_));
(new DeviceShard(dist_.Devices()[i], start, start + size, param_));
});
// compute sketches for each shard
@ -381,12 +379,13 @@ struct GPUSketcher {
}
GPUSketcher(tree::TrainParam param, size_t n_rows) : param_(std::move(param)) {
devices_ = GPUSet::All(param_.n_gpus, n_rows).Normalised(param_.gpu_id);
dist_ = GPUDistribution::Block(GPUSet::All(param_.n_gpus, n_rows).
Normalised(param_.gpu_id));
}
std::vector<std::unique_ptr<DeviceShard>> shards_;
tree::TrainParam param_;
GPUSet devices_;
GPUDistribution dist_;
};
void DeviceSketch

2
src/common/hist_util.h
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@ -67,7 +67,7 @@ struct HistCutUnit {
: cut(cut), size(size) {}
};
/*! \brief cut configuration for all the features */
/*! \brief cut configuration for all the features. */
struct HistCutMatrix {
/*! \brief unit pointer to rows by element position */
std::vector<uint32_t> row_ptr;

6
src/common/host_device_vector.cu
View File

@ -289,6 +289,7 @@ struct HostDeviceVectorImpl {
data_h_.size() * sizeof(T),
cudaMemcpyHostToDevice));
} else {
//
dh::ExecuteShards(&shards_, [&](DeviceShard& shard) { shard.GatherTo(begin); });
}
}
@ -347,7 +348,10 @@ struct HostDeviceVectorImpl {
void Reshard(const GPUDistribution& distribution) {
if (distribution_ == distribution) { return; }
CHECK(distribution_.IsEmpty());
CHECK(distribution_.IsEmpty() || distribution.IsEmpty());
if (distribution.IsEmpty()) {
LazySyncHost(GPUAccess::kWrite);
}
distribution_ = distribution;
InitShards();
}

5
src/common/host_device_vector.h
View File

@ -243,6 +243,11 @@ class HostDeviceVector {
bool HostCanAccess(GPUAccess access) const;
bool DeviceCanAccess(int device, GPUAccess access) const;
/*!
* \brief Specify memory distribution.
*
* If GPUSet::Empty() is used, all data will be drawn back to CPU.
*/
void Reshard(const GPUDistribution& distribution) const;
void Reshard(GPUSet devices) const;
void Resize(size_t new_size, T v = T());

96
src/tree/updater_gpu_hist.cu
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@ -242,7 +242,7 @@ struct DeviceHistogram {
}
/**
* \summary Return pointer to histogram memory for a given node.
* \summary Return pointer to histogram memory for a given node.
* \param nidx Tree node index.
* \return hist pointer.
*/
@ -372,19 +372,19 @@ struct DeviceShard {
// TODO(canonizer): do add support multi-batch DMatrix here
DeviceShard(int device_idx, int normalised_device_idx,
bst_uint row_begin, bst_uint row_end, TrainParam param)
: device_idx(device_idx),
normalised_device_idx(normalised_device_idx),
row_begin_idx(row_begin),
row_end_idx(row_end),
row_stride(0),
n_rows(row_end - row_begin),
n_bins(0),
null_gidx_value(0),
param(param),
prediction_cache_initialised(false),
can_use_smem_atomics(false),
tmp_pinned(nullptr) {}
bst_uint row_begin, bst_uint row_end, TrainParam param) :
device_idx(device_idx),
normalised_device_idx(normalised_device_idx),
row_begin_idx(row_begin),
row_end_idx(row_end),
row_stride(0),
n_rows(row_end - row_begin),
n_bins(0),
null_gidx_value(0),
param(param),
prediction_cache_initialised(false),
can_use_smem_atomics(false),
tmp_pinned(nullptr) {}
void InitRowPtrs(const SparsePage& row_batch) {
dh::safe_cuda(cudaSetDevice(device_idx));
@ -754,7 +754,9 @@ class GPUHistMaker : public TreeUpdater {
param_.InitAllowUnknown(args);
CHECK(param_.n_gpus != 0) << "Must have at least one device";
n_devices_ = param_.n_gpus;
devices_ = GPUSet::All(param_.n_gpus).Normalised(param_.gpu_id);
dist_ =
GPUDistribution::Block(GPUSet::All(param_.n_gpus)
.Normalised(param_.gpu_id));
dh::CheckComputeCapability();
@ -769,7 +771,7 @@ class GPUHistMaker : public TreeUpdater {
void Update(HostDeviceVector<GradientPair>* gpair, DMatrix* dmat,
const std::vector<RegTree*>& trees) override {
monitor_.Start("Update", devices_);
monitor_.Start("Update", dist_.Devices());
GradStats::CheckInfo(dmat->Info());
// rescale learning rate according to size of trees
float lr = param_.learning_rate;
@ -785,7 +787,7 @@ class GPUHistMaker : public TreeUpdater {
LOG(FATAL) << "Exception in gpu_hist: " << e.what() << std::endl;
}
param_.learning_rate = lr;
monitor_.Stop("Update", devices_);
monitor_.Stop("Update", dist_.Devices());
}
void InitDataOnce(DMatrix* dmat) {
@ -801,10 +803,6 @@ class GPUHistMaker : public TreeUpdater {
reducer_.Init(device_list_);
// Partition input matrix into row segments
std::vector<size_t> row_segments;
dh::RowSegments(info_->num_row_, n_devices, &row_segments);
dmlc::DataIter<SparsePage>* iter = dmat->RowIterator();
iter->BeforeFirst();
CHECK(iter->Next()) << "Empty batches are not supported";
@ -812,22 +810,24 @@ class GPUHistMaker : public TreeUpdater {
// Create device shards
shards_.resize(n_devices);
dh::ExecuteIndexShards(&shards_, [&](int i, std::unique_ptr<DeviceShard>& shard) {
size_t start = dist_.ShardStart(info_->num_row_, i);
size_t size = dist_.ShardSize(info_->num_row_, i);
shard = std::unique_ptr<DeviceShard>
(new DeviceShard(device_list_[i], i,
row_segments[i], row_segments[i + 1], param_));
(new DeviceShard(device_list_.at(i), i,
start, start + size, param_));
shard->InitRowPtrs(batch);
});
monitor_.Start("Quantiles", devices_);
monitor_.Start("Quantiles", dist_.Devices());
common::DeviceSketch(batch, *info_, param_, &hmat_);
n_bins_ = hmat_.row_ptr.back();
monitor_.Stop("Quantiles", devices_);
monitor_.Stop("Quantiles", dist_.Devices());
monitor_.Start("BinningCompression", devices_);
monitor_.Start("BinningCompression", dist_.Devices());
dh::ExecuteShards(&shards_, [&](std::unique_ptr<DeviceShard>& shard) {
shard->InitCompressedData(hmat_, batch);
});
monitor_.Stop("BinningCompression", devices_);
monitor_.Stop("BinningCompression", dist_.Devices());
CHECK(!iter->Next()) << "External memory not supported";
@ -837,20 +837,22 @@ class GPUHistMaker : public TreeUpdater {
void InitData(HostDeviceVector<GradientPair>* gpair, DMatrix* dmat,
const RegTree& tree) {
monitor_.Start("InitDataOnce", devices_);
monitor_.Start("InitDataOnce", dist_.Devices());
if (!initialised_) {
this->InitDataOnce(dmat);
}
monitor_.Stop("InitDataOnce", devices_);
monitor_.Stop("InitDataOnce", dist_.Devices());
column_sampler_.Init(info_->num_col_, param_.colsample_bylevel, param_.colsample_bytree);
// Copy gpair & reset memory
monitor_.Start("InitDataReset", devices_);
monitor_.Start("InitDataReset", dist_.Devices());
gpair->Reshard(devices_);
dh::ExecuteShards(&shards_, [&](std::unique_ptr<DeviceShard>& shard) {shard->Reset(gpair); });
monitor_.Stop("InitDataReset", devices_);
gpair->Reshard(dist_);
dh::ExecuteShards(&shards_, [&](std::unique_ptr<DeviceShard>& shard) {
shard->Reset(gpair);
});
monitor_.Stop("InitDataReset", dist_.Devices());
}
void AllReduceHist(int nidx) {
@ -1081,12 +1083,12 @@ class GPUHistMaker : public TreeUpdater {
RegTree* p_tree) {
auto& tree = *p_tree;
monitor_.Start("InitData", devices_);
monitor_.Start("InitData", dist_.Devices());
this->InitData(gpair, p_fmat, *p_tree);
monitor_.Stop("InitData", devices_);
monitor_.Start("InitRoot", devices_);
monitor_.Stop("InitData", dist_.Devices());
monitor_.Start("InitRoot", dist_.Devices());
this->InitRoot(p_tree);
monitor_.Stop("InitRoot", devices_);
monitor_.Stop("InitRoot", dist_.Devices());
auto timestamp = qexpand_->size();
auto num_leaves = 1;
@ -1096,9 +1098,9 @@ class GPUHistMaker : public TreeUpdater {
qexpand_->pop();
if (!candidate.IsValid(param_, num_leaves)) continue;
// std::cout << candidate;
monitor_.Start("ApplySplit", devices_);
monitor_.Start("ApplySplit", dist_.Devices());
this->ApplySplit(candidate, p_tree);
monitor_.Stop("ApplySplit", devices_);
monitor_.Stop("ApplySplit", dist_.Devices());
num_leaves++;
auto left_child_nidx = tree[candidate.nid].LeftChild();
@ -1107,12 +1109,12 @@ class GPUHistMaker : public TreeUpdater {
// Only create child entries if needed
if (ExpandEntry::ChildIsValid(param_, tree.GetDepth(left_child_nidx),
num_leaves)) {
monitor_.Start("BuildHist", devices_);
monitor_.Start("BuildHist", dist_.Devices());
this->BuildHistLeftRight(candidate.nid, left_child_nidx,
right_child_nidx);
monitor_.Stop("BuildHist", devices_);
monitor_.Stop("BuildHist", dist_.Devices());
monitor_.Start("EvaluateSplits", devices_);
monitor_.Start("EvaluateSplits", dist_.Devices());
auto splits =
this->EvaluateSplits({left_child_nidx, right_child_nidx}, p_tree);
qexpand_->push(ExpandEntry(left_child_nidx,
@ -1121,21 +1123,21 @@ class GPUHistMaker : public TreeUpdater {
qexpand_->push(ExpandEntry(right_child_nidx,
tree.GetDepth(right_child_nidx), splits[1],
timestamp++));
monitor_.Stop("EvaluateSplits", devices_);
monitor_.Stop("EvaluateSplits", dist_.Devices());
}
}
}
bool UpdatePredictionCache(
const DMatrix* data, HostDeviceVector<bst_float>* p_out_preds) override {
monitor_.Start("UpdatePredictionCache", devices_);
monitor_.Start("UpdatePredictionCache", dist_.Devices());
if (shards_.empty() || p_last_fmat_ == nullptr || p_last_fmat_ != data)
return false;
p_out_preds->Reshard(devices_);
p_out_preds->Reshard(dist_.Devices());
dh::ExecuteShards(&shards_, [&](std::unique_ptr<DeviceShard>& shard) {
shard->UpdatePredictionCache(p_out_preds->DevicePointer(shard->device_idx));
});
monitor_.Stop("UpdatePredictionCache", devices_);
monitor_.Stop("UpdatePredictionCache", dist_.Devices());
return true;
}
@ -1208,7 +1210,7 @@ class GPUHistMaker : public TreeUpdater {
std::vector<int> device_list_;
DMatrix* p_last_fmat_;
GPUSet devices_;
GPUDistribution dist_;
};
XGBOOST_REGISTER_TREE_UPDATER(GPUHistMaker, "grow_gpu_hist")

11
tests/cpp/common/test_device_helpers.cu
View File

@ -8,6 +8,17 @@
#include "../../../src/common/timer.h"
#include "gtest/gtest.h"
struct Shard { int id; };
TEST(DeviceHelpers, Basic) {
std::vector<Shard> shards (4);
for (int i = 0; i < 4; ++i) {
shards[i].id = i;
}
int sum = dh::ReduceShards<int>(&shards, [](Shard& s) { return s.id ; });
ASSERT_EQ(sum, 6);
}
void CreateTestData(xgboost::bst_uint num_rows, int max_row_size,
thrust::host_vector<int> *row_ptr,
thrust::host_vector<xgboost::bst_uint> *rows) {

2
tests/cpp/common/test_gpu_hist_util.cu
View File

@ -28,7 +28,7 @@ TEST(gpu_hist_util, TestDeviceSketch) {
tree::TrainParam p;
p.max_bin = 20;
p.gpu_id = 0;
p.n_gpus = 1;
p.n_gpus = GPUSet::AllVisible().Size();
// ensure that the exact quantiles are found
p.gpu_batch_nrows = nrows * 10;

48
tests/cpp/common/test_host_device_vector.cu
View File

@ -162,7 +162,7 @@ TEST(HostDeviceVector, TestCopy) {
std::vector<size_t> starts{0, 501};
std::vector<size_t> sizes{501, 500};
SetCudaSetDeviceHandler(SetDevice);
HostDeviceVector<int> v;
{
// a separate scope to ensure that v1 is gone before further checks
@ -178,6 +178,52 @@ TEST(HostDeviceVector, TestCopy) {
SetCudaSetDeviceHandler(nullptr);
}
// The test is not really useful if n_gpus < 2
TEST(HostDeviceVector, Reshard) {
std::vector<int> h_vec (2345);
for (size_t i = 0; i < h_vec.size(); ++i) {
h_vec[i] = i;
}
HostDeviceVector<int> vec (h_vec);
auto devices = GPUSet::AllVisible();
std::vector<size_t> devices_size (devices.Size());
// From CPU to GPUs.
// Assuming we have > 1 devices.
vec.Reshard(devices);
size_t total_size = 0;
for (size_t i = 0; i < devices.Size(); ++i) {
total_size += vec.DeviceSize(i);
devices_size[i] = vec.DeviceSize(i);
}
ASSERT_EQ(total_size, h_vec.size());
ASSERT_EQ(total_size, vec.Size());
auto h_vec_1 = vec.HostVector();
ASSERT_TRUE(std::equal(h_vec_1.cbegin(), h_vec_1.cend(), h_vec.cbegin()));
vec.Reshard(GPUSet::Empty()); // clear out devices memory
// Shrink down the number of devices.
vec.Reshard(GPUSet::Range(0, 1));
ASSERT_EQ(vec.Size(), h_vec.size());
ASSERT_EQ(vec.DeviceSize(0), h_vec.size());
h_vec_1 = vec.HostVector();
ASSERT_TRUE(std::equal(h_vec_1.cbegin(), h_vec_1.cend(), h_vec.cbegin()));
vec.Reshard(GPUSet::Empty()); // clear out devices memory
// Grow the number of devices.
vec.Reshard(devices);
total_size = 0;
for (size_t i = 0; i < devices.Size(); ++i) {
total_size += vec.DeviceSize(i);
ASSERT_EQ(devices_size[i], vec.DeviceSize(i));
}
ASSERT_EQ(total_size, h_vec.size());
ASSERT_EQ(total_size, vec.Size());
h_vec_1 = vec.HostVector();
ASSERT_TRUE(std::equal(h_vec_1.cbegin(), h_vec_1.cend(), h_vec.cbegin()));
}
TEST(HostDeviceVector, Span) {
HostDeviceVector<float> vec {1.0f, 2.0f, 3.0f, 4.0f};
vec.Reshard(GPUSet{0, 1});