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- //---------------------------------------------------------------------------//
- // Copyright (c) 2015 Jakub Szuppe <j.szuppe@gmail.com>
- //
- // Distributed under the Boost Software License, Version 1.0
- // See accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt
- //
- // See http://boostorg.github.com/compute for more information.
- //---------------------------------------------------------------------------//
- #ifndef BOOST_COMPUTE_ALGORITHM_DETAIL_REDUCE_BY_KEY_WITH_SCAN_HPP
- #define BOOST_COMPUTE_ALGORITHM_DETAIL_REDUCE_BY_KEY_WITH_SCAN_HPP
- #include <algorithm>
- #include <iterator>
- #include <boost/compute/command_queue.hpp>
- #include <boost/compute/functional.hpp>
- #include <boost/compute/algorithm/inclusive_scan.hpp>
- #include <boost/compute/container/vector.hpp>
- #include <boost/compute/container/detail/scalar.hpp>
- #include <boost/compute/detail/meta_kernel.hpp>
- #include <boost/compute/detail/iterator_range_size.hpp>
- #include <boost/compute/detail/read_write_single_value.hpp>
- #include <boost/compute/type_traits.hpp>
- #include <boost/compute/utility/program_cache.hpp>
- namespace boost {
- namespace compute {
- namespace detail {
- /// \internal_
- ///
- /// Fills \p new_keys_first with unsigned integer keys generated from vector
- /// of original keys \p keys_first. New keys can be distinguish by simple equality
- /// predicate.
- ///
- /// \param keys_first iterator pointing to the first key
- /// \param number_of_keys number of keys
- /// \param predicate binary predicate for key comparison
- /// \param new_keys_first iterator pointing to the new keys vector
- /// \param preferred_work_group_size preferred work group size
- /// \param queue command queue to perform the operation
- ///
- /// Binary function \p predicate must take two keys as arguments and
- /// return true only if they are considered the same.
- ///
- /// The first new key equals zero and the last equals number of unique keys
- /// minus one.
- ///
- /// No local memory usage.
- template<class InputKeyIterator, class BinaryPredicate>
- inline void generate_uint_keys(InputKeyIterator keys_first,
- size_t number_of_keys,
- BinaryPredicate predicate,
- vector<uint_>::iterator new_keys_first,
- size_t preferred_work_group_size,
- command_queue &queue)
- {
- typedef typename
- std::iterator_traits<InputKeyIterator>::value_type key_type;
- detail::meta_kernel k("reduce_by_key_new_key_flags");
- k.add_set_arg<const uint_>("count", uint_(number_of_keys));
- k <<
- k.decl<const uint_>("gid") << " = get_global_id(0);\n" <<
- k.decl<uint_>("value") << " = 0;\n" <<
- "if(gid >= count){\n return;\n}\n" <<
- "if(gid > 0){ \n" <<
- k.decl<key_type>("key") << " = " <<
- keys_first[k.var<const uint_>("gid")] << ";\n" <<
- k.decl<key_type>("previous_key") << " = " <<
- keys_first[k.var<const uint_>("gid - 1")] << ";\n" <<
- " value = " << predicate(k.var<key_type>("previous_key"),
- k.var<key_type>("key")) <<
- " ? 0 : 1;\n" <<
- "}\n else {\n" <<
- " value = 0;\n" <<
- "}\n" <<
- new_keys_first[k.var<const uint_>("gid")] << " = value;\n";
- const context &context = queue.get_context();
- kernel kernel = k.compile(context);
- size_t work_group_size = preferred_work_group_size;
- size_t work_groups_no = static_cast<size_t>(
- std::ceil(float(number_of_keys) / work_group_size)
- );
- queue.enqueue_1d_range_kernel(kernel,
- 0,
- work_groups_no * work_group_size,
- work_group_size);
- inclusive_scan(new_keys_first, new_keys_first + number_of_keys,
- new_keys_first, queue);
- }
- /// \internal_
- /// Calculate carry-out for each work group.
- /// Carry-out is a pair of the last key processed by a work group and sum of all
- /// values under this key in this work group.
- template<class InputValueIterator, class OutputValueIterator, class BinaryFunction>
- inline void carry_outs(vector<uint_>::iterator keys_first,
- InputValueIterator values_first,
- size_t count,
- vector<uint_>::iterator carry_out_keys_first,
- OutputValueIterator carry_out_values_first,
- BinaryFunction function,
- size_t work_group_size,
- command_queue &queue)
- {
- typedef typename
- std::iterator_traits<OutputValueIterator>::value_type value_out_type;
- detail::meta_kernel k("reduce_by_key_with_scan_carry_outs");
- k.add_set_arg<const uint_>("count", uint_(count));
- size_t local_keys_arg = k.add_arg<uint_ *>(memory_object::local_memory, "lkeys");
- size_t local_vals_arg = k.add_arg<value_out_type *>(memory_object::local_memory, "lvals");
- k <<
- k.decl<const uint_>("gid") << " = get_global_id(0);\n" <<
- k.decl<const uint_>("wg_size") << " = get_local_size(0);\n" <<
- k.decl<const uint_>("lid") << " = get_local_id(0);\n" <<
- k.decl<const uint_>("group_id") << " = get_group_id(0);\n" <<
- k.decl<uint_>("key") << ";\n" <<
- k.decl<value_out_type>("value") << ";\n" <<
- "if(gid < count){\n" <<
- k.var<uint_>("key") << " = " <<
- keys_first[k.var<const uint_>("gid")] << ";\n" <<
- k.var<value_out_type>("value") << " = " <<
- values_first[k.var<const uint_>("gid")] << ";\n" <<
- "lkeys[lid] = key;\n" <<
- "lvals[lid] = value;\n" <<
- "}\n" <<
- // Calculate carry out for each work group by performing Hillis/Steele scan
- // where only last element (key-value pair) is saved
- k.decl<value_out_type>("result") << " = value;\n" <<
- k.decl<uint_>("other_key") << ";\n" <<
- k.decl<value_out_type>("other_value") << ";\n" <<
- "for(" << k.decl<uint_>("offset") << " = 1; " <<
- "offset < wg_size; offset *= 2){\n"
- " barrier(CLK_LOCAL_MEM_FENCE);\n" <<
- " if(lid >= offset){\n"
- " other_key = lkeys[lid - offset];\n" <<
- " if(other_key == key){\n" <<
- " other_value = lvals[lid - offset];\n" <<
- " result = " << function(k.var<value_out_type>("result"),
- k.var<value_out_type>("other_value")) << ";\n" <<
- " }\n" <<
- " }\n" <<
- " barrier(CLK_LOCAL_MEM_FENCE);\n" <<
- " lvals[lid] = result;\n" <<
- "}\n" <<
- // save carry out
- "if(lid == (wg_size - 1)){\n" <<
- carry_out_keys_first[k.var<const uint_>("group_id")] << " = key;\n" <<
- carry_out_values_first[k.var<const uint_>("group_id")] << " = result;\n" <<
- "}\n";
- size_t work_groups_no = static_cast<size_t>(
- std::ceil(float(count) / work_group_size)
- );
- const context &context = queue.get_context();
- kernel kernel = k.compile(context);
- kernel.set_arg(local_keys_arg, local_buffer<uint_>(work_group_size));
- kernel.set_arg(local_vals_arg, local_buffer<value_out_type>(work_group_size));
- queue.enqueue_1d_range_kernel(kernel,
- 0,
- work_groups_no * work_group_size,
- work_group_size);
- }
- /// \internal_
- /// Calculate carry-in by performing inclusive scan by key on carry-outs vector.
- template<class OutputValueIterator, class BinaryFunction>
- inline void carry_ins(vector<uint_>::iterator carry_out_keys_first,
- OutputValueIterator carry_out_values_first,
- OutputValueIterator carry_in_values_first,
- size_t carry_out_size,
- BinaryFunction function,
- size_t work_group_size,
- command_queue &queue)
- {
- typedef typename
- std::iterator_traits<OutputValueIterator>::value_type value_out_type;
- uint_ values_pre_work_item = static_cast<uint_>(
- std::ceil(float(carry_out_size) / work_group_size)
- );
- detail::meta_kernel k("reduce_by_key_with_scan_carry_ins");
- k.add_set_arg<const uint_>("carry_out_size", uint_(carry_out_size));
- k.add_set_arg<const uint_>("values_per_work_item", values_pre_work_item);
- size_t local_keys_arg = k.add_arg<uint_ *>(memory_object::local_memory, "lkeys");
- size_t local_vals_arg = k.add_arg<value_out_type *>(memory_object::local_memory, "lvals");
- k <<
- k.decl<uint_>("id") << " = get_global_id(0) * values_per_work_item;\n" <<
- k.decl<uint_>("idx") << " = id;\n" <<
- k.decl<const uint_>("wg_size") << " = get_local_size(0);\n" <<
- k.decl<const uint_>("lid") << " = get_local_id(0);\n" <<
- k.decl<const uint_>("group_id") << " = get_group_id(0);\n" <<
- k.decl<uint_>("key") << ";\n" <<
- k.decl<value_out_type>("value") << ";\n" <<
- k.decl<uint_>("previous_key") << ";\n" <<
- k.decl<value_out_type>("result") << ";\n" <<
- "if(id < carry_out_size){\n" <<
- k.var<uint_>("previous_key") << " = " <<
- carry_out_keys_first[k.var<const uint_>("id")] << ";\n" <<
- k.var<value_out_type>("result") << " = " <<
- carry_out_values_first[k.var<const uint_>("id")] << ";\n" <<
- carry_in_values_first[k.var<const uint_>("id")] << " = result;\n" <<
- "}\n" <<
- k.decl<const uint_>("end") << " = (id + values_per_work_item) <= carry_out_size" <<
- " ? (values_per_work_item + id) : carry_out_size;\n" <<
- "for(idx = idx + 1; idx < end; idx += 1){\n" <<
- " key = " << carry_out_keys_first[k.var<const uint_>("idx")] << ";\n" <<
- " value = " << carry_out_values_first[k.var<const uint_>("idx")] << ";\n" <<
- " if(previous_key == key){\n" <<
- " result = " << function(k.var<value_out_type>("result"),
- k.var<value_out_type>("value")) << ";\n" <<
- " }\n else { \n" <<
- " result = value;\n"
- " }\n" <<
- " " << carry_in_values_first[k.var<const uint_>("idx")] << " = result;\n" <<
- " previous_key = key;\n"
- "}\n" <<
- // save the last key and result to local memory
- "lkeys[lid] = previous_key;\n" <<
- "lvals[lid] = result;\n" <<
- // Hillis/Steele scan
- "for(" << k.decl<uint_>("offset") << " = 1; " <<
- "offset < wg_size; offset *= 2){\n"
- " barrier(CLK_LOCAL_MEM_FENCE);\n" <<
- " if(lid >= offset){\n"
- " key = lkeys[lid - offset];\n" <<
- " if(previous_key == key){\n" <<
- " value = lvals[lid - offset];\n" <<
- " result = " << function(k.var<value_out_type>("result"),
- k.var<value_out_type>("value")) << ";\n" <<
- " }\n" <<
- " }\n" <<
- " barrier(CLK_LOCAL_MEM_FENCE);\n" <<
- " lvals[lid] = result;\n" <<
- "}\n" <<
- "barrier(CLK_LOCAL_MEM_FENCE);\n" <<
- "if(lid > 0){\n" <<
- // load key-value reduced by previous work item
- " previous_key = lkeys[lid - 1];\n" <<
- " result = lvals[lid - 1];\n" <<
- "}\n" <<
- // add key-value reduced by previous work item
- "for(idx = id; idx < id + values_per_work_item; idx += 1){\n" <<
- // make sure all carry-ins are saved in global memory
- " barrier( CLK_GLOBAL_MEM_FENCE );\n" <<
- " if(lid > 0 && idx < carry_out_size) {\n"
- " key = " << carry_out_keys_first[k.var<const uint_>("idx")] << ";\n" <<
- " value = " << carry_in_values_first[k.var<const uint_>("idx")] << ";\n" <<
- " if(previous_key == key){\n" <<
- " value = " << function(k.var<value_out_type>("result"),
- k.var<value_out_type>("value")) << ";\n" <<
- " }\n" <<
- " " << carry_in_values_first[k.var<const uint_>("idx")] << " = value;\n" <<
- " }\n" <<
- "}\n";
- const context &context = queue.get_context();
- kernel kernel = k.compile(context);
- kernel.set_arg(local_keys_arg, local_buffer<uint_>(work_group_size));
- kernel.set_arg(local_vals_arg, local_buffer<value_out_type>(work_group_size));
- queue.enqueue_1d_range_kernel(kernel,
- 0,
- work_group_size,
- work_group_size);
- }
- /// \internal_
- ///
- /// Perform final reduction by key. Each work item:
- /// 1. Perform local work-group reduction (Hillis/Steele scan)
- /// 2. Add carry-in (if keys are right)
- /// 3. Save reduced value if next key is different than processed one
- template<class InputKeyIterator, class InputValueIterator,
- class OutputKeyIterator, class OutputValueIterator,
- class BinaryFunction>
- inline void final_reduction(InputKeyIterator keys_first,
- InputValueIterator values_first,
- OutputKeyIterator keys_result,
- OutputValueIterator values_result,
- size_t count,
- BinaryFunction function,
- vector<uint_>::iterator new_keys_first,
- vector<uint_>::iterator carry_in_keys_first,
- OutputValueIterator carry_in_values_first,
- size_t carry_in_size,
- size_t work_group_size,
- command_queue &queue)
- {
- typedef typename
- std::iterator_traits<OutputValueIterator>::value_type value_out_type;
- detail::meta_kernel k("reduce_by_key_with_scan_final_reduction");
- k.add_set_arg<const uint_>("count", uint_(count));
- size_t local_keys_arg = k.add_arg<uint_ *>(memory_object::local_memory, "lkeys");
- size_t local_vals_arg = k.add_arg<value_out_type *>(memory_object::local_memory, "lvals");
- k <<
- k.decl<const uint_>("gid") << " = get_global_id(0);\n" <<
- k.decl<const uint_>("wg_size") << " = get_local_size(0);\n" <<
- k.decl<const uint_>("lid") << " = get_local_id(0);\n" <<
- k.decl<const uint_>("group_id") << " = get_group_id(0);\n" <<
- k.decl<uint_>("key") << ";\n" <<
- k.decl<value_out_type>("value") << ";\n"
- "if(gid < count){\n" <<
- k.var<uint_>("key") << " = " <<
- new_keys_first[k.var<const uint_>("gid")] << ";\n" <<
- k.var<value_out_type>("value") << " = " <<
- values_first[k.var<const uint_>("gid")] << ";\n" <<
- "lkeys[lid] = key;\n" <<
- "lvals[lid] = value;\n" <<
- "}\n" <<
- // Hillis/Steele scan
- k.decl<value_out_type>("result") << " = value;\n" <<
- k.decl<uint_>("other_key") << ";\n" <<
- k.decl<value_out_type>("other_value") << ";\n" <<
- "for(" << k.decl<uint_>("offset") << " = 1; " <<
- "offset < wg_size ; offset *= 2){\n"
- " barrier(CLK_LOCAL_MEM_FENCE);\n" <<
- " if(lid >= offset) {\n" <<
- " other_key = lkeys[lid - offset];\n" <<
- " if(other_key == key){\n" <<
- " other_value = lvals[lid - offset];\n" <<
- " result = " << function(k.var<value_out_type>("result"),
- k.var<value_out_type>("other_value")) << ";\n" <<
- " }\n" <<
- " }\n" <<
- " barrier(CLK_LOCAL_MEM_FENCE);\n" <<
- " lvals[lid] = result;\n" <<
- "}\n" <<
- "if(gid >= count) {\n return;\n};\n" <<
- k.decl<const bool>("save") << " = (gid < (count - 1)) ?"
- << new_keys_first[k.var<const uint_>("gid + 1")] << " != key" <<
- ": true;\n" <<
- // Add carry in
- k.decl<uint_>("carry_in_key") << ";\n" <<
- "if(group_id > 0 && save) {\n" <<
- " carry_in_key = " << carry_in_keys_first[k.var<const uint_>("group_id - 1")] << ";\n" <<
- " if(key == carry_in_key){\n" <<
- " other_value = " << carry_in_values_first[k.var<const uint_>("group_id - 1")] << ";\n" <<
- " result = " << function(k.var<value_out_type>("result"),
- k.var<value_out_type>("other_value")) << ";\n" <<
- " }\n" <<
- "}\n" <<
- // Save result only if the next key is different or it's the last element.
- "if(save){\n" <<
- keys_result[k.var<uint_>("key")] << " = " << keys_first[k.var<const uint_>("gid")] << ";\n" <<
- values_result[k.var<uint_>("key")] << " = result;\n" <<
- "}\n"
- ;
- size_t work_groups_no = static_cast<size_t>(
- std::ceil(float(count) / work_group_size)
- );
- const context &context = queue.get_context();
- kernel kernel = k.compile(context);
- kernel.set_arg(local_keys_arg, local_buffer<uint_>(work_group_size));
- kernel.set_arg(local_vals_arg, local_buffer<value_out_type>(work_group_size));
- queue.enqueue_1d_range_kernel(kernel,
- 0,
- work_groups_no * work_group_size,
- work_group_size);
- }
- /// \internal_
- /// Returns preferred work group size for reduce by key with scan algorithm.
- template<class KeyType, class ValueType>
- inline size_t get_work_group_size(const device& device)
- {
- std::string cache_key = std::string("__boost_reduce_by_key_with_scan")
- + "k_" + type_name<KeyType>() + "_v_" + type_name<ValueType>();
- // load parameters
- boost::shared_ptr<parameter_cache> parameters =
- detail::parameter_cache::get_global_cache(device);
- return (std::max)(
- static_cast<size_t>(parameters->get(cache_key, "wgsize", 256)),
- static_cast<size_t>(device.get_info<CL_DEVICE_MAX_WORK_GROUP_SIZE>())
- );
- }
- /// \internal_
- ///
- /// 1. For each work group carry-out value is calculated (it's done by key-oriented
- /// Hillis/Steele scan). Carry-out is a pair of the last key processed by work
- /// group and sum of all values under this key in work group.
- /// 2. From every carry-out carry-in is calculated by performing inclusive scan
- /// by key.
- /// 3. Final reduction by key is performed (key-oriented Hillis/Steele scan),
- /// carry-in values are added where needed.
- template<class InputKeyIterator, class InputValueIterator,
- class OutputKeyIterator, class OutputValueIterator,
- class BinaryFunction, class BinaryPredicate>
- inline size_t reduce_by_key_with_scan(InputKeyIterator keys_first,
- InputKeyIterator keys_last,
- InputValueIterator values_first,
- OutputKeyIterator keys_result,
- OutputValueIterator values_result,
- BinaryFunction function,
- BinaryPredicate predicate,
- command_queue &queue)
- {
- typedef typename
- std::iterator_traits<InputValueIterator>::value_type value_type;
- typedef typename
- std::iterator_traits<InputKeyIterator>::value_type key_type;
- typedef typename
- std::iterator_traits<OutputValueIterator>::value_type value_out_type;
- const context &context = queue.get_context();
- size_t count = detail::iterator_range_size(keys_first, keys_last);
- if(count == 0){
- return size_t(0);
- }
- const device &device = queue.get_device();
- size_t work_group_size = get_work_group_size<value_type, key_type>(device);
- // Replace original key with unsigned integer keys generated based on given
- // predicate. New key is also an index for keys_result and values_result vectors,
- // which points to place where reduced value should be saved.
- vector<uint_> new_keys(count, context);
- vector<uint_>::iterator new_keys_first = new_keys.begin();
- generate_uint_keys(keys_first, count, predicate, new_keys_first,
- work_group_size, queue);
- // Calculate carry-out and carry-in vectors size
- const size_t carry_out_size = static_cast<size_t>(
- std::ceil(float(count) / work_group_size)
- );
- vector<uint_> carry_out_keys(carry_out_size, context);
- vector<value_out_type> carry_out_values(carry_out_size, context);
- carry_outs(new_keys_first, values_first, count, carry_out_keys.begin(),
- carry_out_values.begin(), function, work_group_size, queue);
- vector<value_out_type> carry_in_values(carry_out_size, context);
- carry_ins(carry_out_keys.begin(), carry_out_values.begin(),
- carry_in_values.begin(), carry_out_size, function, work_group_size,
- queue);
- final_reduction(keys_first, values_first, keys_result, values_result,
- count, function, new_keys_first, carry_out_keys.begin(),
- carry_in_values.begin(), carry_out_size, work_group_size,
- queue);
- const size_t result = read_single_value<uint_>(new_keys.get_buffer(),
- count - 1, queue);
- return result + 1;
- }
- /// \internal_
- /// Return true if requirements for running reduce by key with scan on given
- /// device are met (at least one work group of preferred size can be run).
- template<class InputKeyIterator, class InputValueIterator,
- class OutputKeyIterator, class OutputValueIterator>
- bool reduce_by_key_with_scan_requirements_met(InputKeyIterator keys_first,
- InputValueIterator values_first,
- OutputKeyIterator keys_result,
- OutputValueIterator values_result,
- const size_t count,
- command_queue &queue)
- {
- typedef typename
- std::iterator_traits<InputValueIterator>::value_type value_type;
- typedef typename
- std::iterator_traits<InputKeyIterator>::value_type key_type;
- typedef typename
- std::iterator_traits<OutputValueIterator>::value_type value_out_type;
- (void) keys_first;
- (void) values_first;
- (void) keys_result;
- (void) values_result;
- const device &device = queue.get_device();
- // device must have dedicated local memory storage
- if(device.get_info<CL_DEVICE_LOCAL_MEM_TYPE>() != CL_LOCAL)
- {
- return false;
- }
- // local memory size in bytes (per compute unit)
- const size_t local_mem_size = device.get_info<CL_DEVICE_LOCAL_MEM_SIZE>();
- // preferred work group size
- size_t work_group_size = get_work_group_size<key_type, value_type>(device);
- // local memory size needed to perform parallel reduction
- size_t required_local_mem_size = 0;
- // keys size
- required_local_mem_size += sizeof(uint_) * work_group_size;
- // reduced values size
- required_local_mem_size += sizeof(value_out_type) * work_group_size;
- return (required_local_mem_size <= local_mem_size);
- }
- } // end detail namespace
- } // end compute namespace
- } // end boost namespace
- #endif // BOOST_COMPUTE_ALGORITHM_DETAIL_REDUCE_BY_KEY_WITH_SCAN_HPP
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