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Use quantised gradients in gpu_hist histograms (#8246)

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This commit is contained in:
Rory Mitchell
2022-09-26 17:35:35 +02:00
committed by GitHub
parent 4056974e37
commit 8f77677193
14 changed files with 394 additions and 336 deletions
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38
src/common/device_helpers.cuh
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@@ -1511,44 +1511,6 @@ XGBOOST_DEV_INLINE void AtomicAddGpair(OutputGradientT* dest,
static_cast<typename OutputGradientT::ValueT>(gpair.GetHess()));
}
/**
* \brief An atomicAdd designed for gradient pair with better performance. For general
* int64_t atomicAdd, one can simply cast it to unsigned long long.
*/
XGBOOST_DEV_INLINE void AtomicAdd64As32(int64_t *dst, int64_t src) {
uint32_t* y_low = reinterpret_cast<uint32_t *>(dst);
uint32_t *y_high = y_low + 1;
auto cast_src = reinterpret_cast<uint64_t *>(&src);
uint32_t const x_low = static_cast<uint32_t>(src);
uint32_t const x_high = (*cast_src) >> 32;
auto const old = atomicAdd(y_low, x_low);
uint32_t const carry = old > (std::numeric_limits<uint32_t>::max() - x_low) ? 1 : 0;
uint32_t const sig = x_high + carry;
atomicAdd(y_high, sig);
}
XGBOOST_DEV_INLINE void
AtomicAddGpair(xgboost::GradientPairInt64 *dest,
xgboost::GradientPairInt64 const &gpair) {
auto dst_ptr = reinterpret_cast<int64_t *>(dest);
auto g = gpair.GetGrad();
auto h = gpair.GetHess();
AtomicAdd64As32(dst_ptr, g);
AtomicAdd64As32(dst_ptr + 1, h);
}
XGBOOST_DEV_INLINE void
AtomicAddGpair(xgboost::GradientPairInt32 *dest,
xgboost::GradientPairInt32 const &gpair) {
auto dst_ptr = reinterpret_cast<typename xgboost::GradientPairInt32::ValueT*>(dest);
::atomicAdd(dst_ptr, static_cast<int>(gpair.GetGrad()));
::atomicAdd(dst_ptr + 1, static_cast<int>(gpair.GetHess()));
}
// Thrust version of this function causes error on Windows
template <typename ReturnT, typename IterT, typename FuncT>