-
-
Notifications
You must be signed in to change notification settings - Fork 8.7k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Optimized EvaluateSplut function (#5138)
* Add block based threading utilities.
- Loading branch information
1 parent
04db125
commit 7b17e76
Showing
5 changed files
with
315 additions
and
45 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,123 @@ | ||
| /*! | ||
| * Copyright 2015-2019 by Contributors | ||
| * \file common.h | ||
| * \brief Threading utilities | ||
| */ | ||
| #ifndef XGBOOST_COMMON_THREADING_UTILS_H_ | ||
| #define XGBOOST_COMMON_THREADING_UTILS_H_ | ||
|
|
||
| #include <vector> | ||
| #include <algorithm> | ||
|
|
||
| namespace xgboost { | ||
| namespace common { | ||
|
|
||
| // Represent simple range of indexes [begin, end) | ||
| // Inspired by tbb::blocked_range | ||
| class Range1d { | ||
| public: | ||
| Range1d(size_t begin, size_t end): begin_(begin), end_(end) { | ||
| CHECK_LT(begin, end); | ||
| } | ||
|
|
||
| size_t begin() { | ||
| return begin_; | ||
| } | ||
|
|
||
| size_t end() { | ||
| return end_; | ||
| } | ||
|
|
||
| private: | ||
| size_t begin_; | ||
| size_t end_; | ||
| }; | ||
|
|
||
|
|
||
| // Split 2d space to balanced blocks | ||
| // Implementation of the class is inspired by tbb::blocked_range2d | ||
| // However, TBB provides only (n x m) 2d range (matrix) separated by blocks. Example: | ||
| // [ 1,2,3 ] | ||
| // [ 4,5,6 ] | ||
| // [ 7,8,9 ] | ||
| // But the class is able to work with different sizes in each 'row'. Example: | ||
| // [ 1,2 ] | ||
| // [ 3,4,5,6 ] | ||
| // [ 7,8,9] | ||
| // If grain_size is 2: It produces following blocks: | ||
| // [1,2], [3,4], [5,6], [7,8], [9] | ||
| // The class helps to process data in several tree nodes (non-balanced usually) in parallel | ||
| // Using nested parallelism (by nodes and by data in each node) | ||
| // it helps to improve CPU resources utilization | ||
| class BlockedSpace2d { | ||
| public: | ||
| // Example of space: | ||
| // [ 1,2 ] | ||
| // [ 3,4,5,6 ] | ||
| // [ 7,8,9] | ||
| // BlockedSpace2d will create following blocks (tasks) if grain_size=2: | ||
| // 1-block: first_dimension = 0, range of indexes in a 'row' = [0,2) (includes [1,2] values) | ||
| // 2-block: first_dimension = 1, range of indexes in a 'row' = [0,2) (includes [3,4] values) | ||
| // 3-block: first_dimension = 1, range of indexes in a 'row' = [2,4) (includes [5,6] values) | ||
| // 4-block: first_dimension = 2, range of indexes in a 'row' = [0,2) (includes [7,8] values) | ||
| // 5-block: first_dimension = 2, range of indexes in a 'row' = [2,3) (includes [9] values) | ||
| // Arguments: | ||
| // dim1 - size of the first dimension in the space | ||
| // getter_size_dim2 - functor to get the second dimensions for each 'row' by row-index | ||
| // grain_size - max size of produced blocks | ||
| template<typename Func> | ||
| BlockedSpace2d(size_t dim1, Func getter_size_dim2, size_t grain_size) { | ||
| for (size_t i = 0; i < dim1; ++i) { | ||
| const size_t size = getter_size_dim2(i); | ||
| const size_t n_blocks = size/grain_size + !!(size % grain_size); | ||
| for (size_t iblock = 0; iblock < n_blocks; ++iblock) { | ||
| const size_t begin = iblock * grain_size; | ||
| const size_t end = std::min(begin + grain_size, size); | ||
| AddBlock(i, begin, end); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // Amount of blocks(tasks) in a space | ||
| size_t Size() const { | ||
| return ranges_.size(); | ||
| } | ||
|
|
||
| // get index of the first dimension of i-th block(task) | ||
| size_t GetFirstDimension(size_t i) const { | ||
| CHECK_LT(i, first_dimension_.size()); | ||
| return first_dimension_[i]; | ||
| } | ||
|
|
||
| // get a range of indexes for the second dimension of i-th block(task) | ||
| Range1d GetRange(size_t i) const { | ||
| CHECK_LT(i, ranges_.size()); | ||
| return ranges_[i]; | ||
| } | ||
|
|
||
| private: | ||
| void AddBlock(size_t first_dimension, size_t begin, size_t end) { | ||
| first_dimension_.push_back(first_dimension); | ||
| ranges_.emplace_back(begin, end); | ||
| } | ||
|
|
||
| std::vector<Range1d> ranges_; | ||
| std::vector<size_t> first_dimension_; | ||
| }; | ||
|
|
||
|
|
||
| // Wrapper to implement nested parallelism with simple omp parallel for | ||
| template<typename Func> | ||
| void ParallelFor2d(const BlockedSpace2d& space, Func func) { | ||
| const int num_blocks_in_space = static_cast<int>(space.Size()); | ||
|
|
||
| #pragma omp parallel for | ||
| for (auto i = 0; i < num_blocks_in_space; i++) { | ||
| func(space.GetFirstDimension(i), space.GetRange(i)); | ||
| } | ||
| } | ||
|
|
||
| } // namespace common | ||
| } // namespace xgboost | ||
|
|
||
| #endif // XGBOOST_COMMON_THREADING_UTILS_H_ |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.