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Multi-GPU HostDeviceVector. (#3287)

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* Multi-GPU HostDeviceVector.

- HostDeviceVector instances can now span multiple devices, defined by GPUSet struct
- the interface of HostDeviceVector has been modified accordingly
- GPU objective functions are now multi-GPU
- GPU predicting from cache is now multi-GPU
- avoiding omp_set_num_threads() calls
- other minor changes
This commit is contained in:
Andrew V. Adinetz
2018-05-04 22:00:05 +02:00
committed by Rory Mitchell
parent 90a5c4db9d
commit b8a0d66fe6
9 changed files with 569 additions and 250 deletions
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49
src/predictor/gpu_predictor.cu
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@@ -310,8 +310,11 @@ class GPUPredictor : public xgboost::Predictor {
tree_group.begin());
device_matrix->predictions.resize(out_preds->Size());
thrust::copy(out_preds->tbegin(param.gpu_id), out_preds->tend(param.gpu_id),
device_matrix->predictions.begin());
auto& predictions = device_matrix->predictions;
out_preds->GatherTo(predictions.data(),
predictions.data() + predictions.size());
dh::safe_cuda(cudaSetDevice(param.gpu_id));
const int BLOCK_THREADS = 128;
const int GRID_SIZE = static_cast<int>(
@@ -335,9 +338,8 @@ class GPUPredictor : public xgboost::Predictor {
model.param.num_output_group);
dh::safe_cuda(cudaDeviceSynchronize());
thrust::copy(device_matrix->predictions.begin(),
device_matrix->predictions.end(),
out_preds->tbegin(param.gpu_id));
out_preds->ScatterFrom(predictions.data(),
predictions.data() + predictions.size());
}
public:
@@ -366,14 +368,13 @@ class GPUPredictor : public xgboost::Predictor {
const gbm::GBTreeModel& model) const {
size_t n = model.param.num_output_group * info.num_row_;
const std::vector<bst_float>& base_margin = info.base_margin_;
out_preds->Resize(n, 0.0f, param.gpu_id);
out_preds->Reshard(devices);
out_preds->Resize(n);
if (base_margin.size() != 0) {
CHECK_EQ(out_preds->Size(), n);
thrust::copy(base_margin.begin(), base_margin.end(),
out_preds->tbegin(param.gpu_id));
out_preds->Copy(base_margin);
} else {
thrust::fill(out_preds->tbegin(param.gpu_id),
out_preds->tend(param.gpu_id), model.base_margin);
out_preds->Fill(model.base_margin);
}
}
@@ -385,11 +386,9 @@ class GPUPredictor : public xgboost::Predictor {
if (it != cache_.end()) {
HostDeviceVector<bst_float>& y = it->second.predictions;
if (y.Size() != 0) {
dh::safe_cuda(cudaSetDevice(param.gpu_id));
out_preds->Resize(y.Size(), 0.0f, param.gpu_id);
dh::safe_cuda(cudaMemcpy(
out_preds->DevicePointer(param.gpu_id), y.DevicePointer(param.gpu_id),
out_preds->Size() * sizeof(bst_float), cudaMemcpyDefault));
out_preds->Reshard(devices);
out_preds->Resize(y.Size());
out_preds->Copy(&y);
return true;
}
}
@@ -410,18 +409,15 @@ class GPUPredictor : public xgboost::Predictor {
HostDeviceVector<bst_float>& predictions = e.predictions;
if (predictions.Size() == 0) {
// ensure that the device in predictions is correct
predictions.Resize(0, 0.0f, param.gpu_id);
cpu_predictor->PredictBatch(dmat, &predictions, model, 0,
static_cast<bst_uint>(model.trees.size()));
} else if (model.param.num_output_group == 1 && updaters->size() > 0 &&
num_new_trees == 1 &&
updaters->back()->UpdatePredictionCache(e.data.get(),
&predictions)) {
this->InitOutPredictions(dmat->Info(), &predictions, model);
}
if (model.param.num_output_group == 1 && updaters->size() > 0 &&
num_new_trees == 1 &&
updaters->back()->UpdatePredictionCache(e.data.get(), &predictions)) {
// do nothing
} else {
DevicePredictInternal(dmat, &predictions, model, old_ntree,
model.trees.size());
DevicePredictInternal(dmat, &predictions, model, old_ntree, model.trees.size());
}
}
}
@@ -462,6 +458,7 @@ class GPUPredictor : public xgboost::Predictor {
Predictor::Init(cfg, cache);
cpu_predictor->Init(cfg, cache);
param.InitAllowUnknown(cfg);
devices = GPUSet::Range(param.gpu_id, dh::NDevicesAll(param.n_gpus));
max_shared_memory_bytes = dh::MaxSharedMemory(param.gpu_id);
}
@@ -473,6 +470,8 @@ class GPUPredictor : public xgboost::Predictor {
thrust::device_vector<DevicePredictionNode> nodes;
thrust::device_vector<size_t> tree_segments;
thrust::device_vector<int> tree_group;
thrust::device_vector<bst_float> preds;
GPUSet devices;
size_t max_shared_memory_bytes;
};
XGBOOST_REGISTER_PREDICTOR(GPUPredictor, "gpu_predictor")