Fix dart inplace prediction with GPU input. #6777
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trivialfis
commented
Mar 24, 2021
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trivialfis
commented
- On C API there's a check for output prediction being device-readable. With dart this doesn't hold.
- Added optimization to avoid memory copying whenever possible. Will post the result later.
* Fix dart inplace predict with data on GPU, which might trigger a fatal check for device access right. * Avoid copying data whenever possible.
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trivialfis
commented
Mar 24, 2021
| const auto& host_data = page.data.ConstHostVector(); | ||
| dh::device_vector<Entry> sorted_entries(host_data.begin() + begin, | ||
| host_data.begin() + end); | ||
| dh::device_vector<Entry> sorted_entries; |
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This is to avoid copying data when input is already on GPU.
| @@ -92,7 +92,10 @@ class HostDeviceVectorImpl { | |||
| } else { | |||
| gpu_access_ = GPUAccess::kWrite; | |||
| SetDevice(); | |||
| thrust::fill(data_d_->begin(), data_d_->end(), v); | |||
| auto s_data = dh::ToSpan(*data_d_); | |||
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Avoid synchronization.
| dh::safe_cuda(cudaMemcpyAsync(entries_d.data().get(), | ||
| data_vec.data() + ent_cnt_begin, | ||
| n_entries * sizeof(Entry), cudaMemcpyDefault)); | ||
| if (row_batch.data.DeviceCanRead()) { |
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Avoid copying data when it's already on GPU.
|
100 rounds on higgs: Before: After: |
hcho3
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Mar 25, 2021
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Trying to understand what this PR does. Is it correct to summarize it as thus:
- Current behavior: Copy the predicted scores
predts.predictionsto the host before summing them intoh_out_predts - New behavior: Sum the predicted scores
predts.predictionsintopredts.predictions.DeviceSpan(), keeping all the data on the device.
| thrust::fill(data_d_->begin(), data_d_->end(), v); | ||
| auto s_data = dh::ToSpan(*data_d_); | ||
| dh::LaunchN(device_, data_d_->size(), [=]XGBOOST_DEVICE(size_t i) { | ||
| s_data[i] = v; |
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Should we use the bound-checked interface here, given that the size of data_d_ is already clear?
Your summary is correct. |
RAMitchell
approved these changes
Mar 25, 2021
hcho3
approved these changes
Mar 25, 2021
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