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| author | Miles Macklin <[email protected]> | 2017-03-10 14:51:31 +1300 |
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| committer | Miles Macklin <[email protected]> | 2017-03-10 14:51:31 +1300 |
| commit | ad3d90fafe5ee79964bdfe1f1e0704c3ffcdfd5f (patch) | |
| tree | 4cc6f3288363889d7342f7f8407c0251e6904819 /external/cub-1.3.2/cub/device/device_reduce.cuh | |
| download | flex-ad3d90fafe5ee79964bdfe1f1e0704c3ffcdfd5f.tar.xz flex-ad3d90fafe5ee79964bdfe1f1e0704c3ffcdfd5f.zip | |
Initial 1.1.0 binary release
Diffstat (limited to 'external/cub-1.3.2/cub/device/device_reduce.cuh')
| -rw-r--r-- | external/cub-1.3.2/cub/device/device_reduce.cuh | 804 |
1 files changed, 804 insertions, 0 deletions
diff --git a/external/cub-1.3.2/cub/device/device_reduce.cuh b/external/cub-1.3.2/cub/device/device_reduce.cuh new file mode 100644 index 0000000..480248b --- /dev/null +++ b/external/cub-1.3.2/cub/device/device_reduce.cuh @@ -0,0 +1,804 @@ + +/****************************************************************************** + * Copyright (c) 2011, Duane Merrill. All rights reserved. + * Copyright (c) 2011-2014, NVIDIA CORPORATION. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * * Neither the name of the NVIDIA CORPORATION nor the + * names of its contributors may be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL NVIDIA CORPORATION BE LIABLE FOR ANY + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + ******************************************************************************/ + +/** + * \file + * cub::DeviceReduce provides device-wide, parallel operations for computing a reduction across a sequence of data items residing within global memory. + */ + +#pragma once + +#include <stdio.h> +#include <iterator> + +#include "dispatch/device_reduce_dispatch.cuh" +#include "../util_namespace.cuh" + +/// Optional outer namespace(s) +CUB_NS_PREFIX + +/// CUB namespace +namespace cub { + + +/** + * \brief DeviceReduce provides device-wide, parallel operations for computing a reduction across a sequence of data items residing within global memory.  + * \ingroup DeviceModule + * + * \par Overview + * A <a href="http://en.wikipedia.org/wiki/Reduce_(higher-order_function)"><em>reduction</em></a> (or <em>fold</em>) + * uses a binary combining operator to compute a single aggregate from a sequence of input elements. + * + * \par Usage Considerations + * \cdp_class{DeviceReduce} + * + * \par Performance + * \linear_performance{reduction, reduce-by-key, and run-length encode} + * + * \par + * The following chart illustrates DeviceReduce::Sum + * performance across different CUDA architectures for \p int32 keys. + * + * \image html reduce_int32.png + * + * \par + * The following chart illustrates DeviceReduce::ReduceByKey (summation) + * performance across different CUDA architectures for \p fp32 + * values. Segments are identified by \p int32 keys, and have lengths uniformly sampled from [1,1000]. + * + * \image html reduce_by_key_fp32_len_500.png + * + * \par + * The following chart illustrates DeviceReduce::RunLengthEncode performance across + * different CUDA architectures for \p int32 items. + * Segments have lengths uniformly sampled from [1,1000]. + * + * \image html rle_int32_len_500.png + * + * \par + * \plots_below + * + * + */ +struct DeviceReduce +{ + /** + * \brief Computes a device-wide reduction using the specified binary \p reduction_op functor. + * + * \par + * - Does not support non-commutative reduction operators. + * - \devicestorage + * - \cdp + * + * \par Performance + * Performance is typically similar to DeviceReduce::Sum. + * + * \par Snippet + * The code snippet below illustrates a custom min reduction of a device vector of \p int items. + * \par + * \code + * #include <cub/cub.cuh> // or equivalently <cub/device/device_radix_sort.cuh> + * + * // CustomMin functor + * struct CustomMin + * { + * template <typename T> + * CUB_RUNTIME_FUNCTION __forceinline__ + * T operator()(const T &a, const T &b) const { + * return (b < a) ? b : a; + * } + * }; + * + * // Declare, allocate, and initialize device pointers for input and output + * int num_items; // e.g., 7 + * int *d_in; // e.g., [8, 6, 7, 5, 3, 0, 9] + * int *d_out; // e.g., [ ] + * CustomMin min_op; + * ... + * + * // Determine temporary device storage requirements + * void *d_temp_storage = NULL; + * size_t temp_storage_bytes = 0; + * cub::DeviceReduce::Reduce(d_temp_storage, temp_storage_bytes, d_in, d_out, num_items, min_op); + * + * // Allocate temporary storage + * cudaMalloc(&d_temp_storage, temp_storage_bytes); + * + * // Run reduction + * cub::DeviceReduce::Reduce(d_temp_storage, temp_storage_bytes, d_in, d_out, num_items, min_op); + * + * // d_out <-- [0] + * + * \endcode + * + * \tparam InputIterator <b>[inferred]</b> Random-access input iterator type for reading input items \iterator + * \tparam OutputIterator <b>[inferred]</b> Output iterator type for recording the reduced aggregate \iterator + * \tparam ReductionOp <b>[inferred]</b> Binary reduction functor type having member <tt>T operator()(const T &a, const T &b)</tt> + */ + template < + typename InputIterator, + typename OutputIterator, + typename ReductionOp> + CUB_RUNTIME_FUNCTION + static cudaError_t Reduce( + void *d_temp_storage, ///< [in] %Device allocation of temporary storage. When NULL, the required allocation size is written to \p temp_storage_bytes and no work is done. + size_t &temp_storage_bytes, ///< [in,out] Reference to size in bytes of \p d_temp_storage allocation + InputIterator d_in, ///< [in] Pointer to the input sequence of data items + OutputIterator d_out, ///< [out] Pointer to the output aggregate + int num_items, ///< [in] Total number of input items (i.e., length of \p d_in) + ReductionOp reduction_op, ///< [in] Binary reduction functor (e.g., an instance of cub::Sum, cub::Min, cub::Max, etc.) + cudaStream_t stream = 0, ///< [in] <b>[optional]</b> CUDA stream to launch kernels within. Default is stream<sub>0</sub>. + bool debug_synchronous = false) ///< [in] <b>[optional]</b> Whether or not to synchronize the stream after every kernel launch to check for errors. Also causes launch configurations to be printed to the console. Default is \p false. + { + // Signed integer type for global offsets + typedef int Offset; + + // Dispatch type + typedef DeviceReduceDispatch<InputIterator, OutputIterator, Offset, ReductionOp> DeviceReduceDispatch; + + return DeviceReduceDispatch::Dispatch( + d_temp_storage, + temp_storage_bytes, + d_in, + d_out, + num_items, + reduction_op, + stream, + debug_synchronous); + } + + + /** + * \brief Computes a device-wide sum using the addition ('+') operator. + * + * \par + * - Does not support non-commutative reduction operators. + * - \devicestorage + * - \cdp + * + * \par Performance + * The following charts illustrate saturated reduction (sum) performance across different + * CUDA architectures for \p int32 and \p int64 items, respectively. + * + * \image html reduce_int32.png + * \image html reduce_int64.png + * + * \par Snippet + * The code snippet below illustrates the sum reduction of a device vector of \p int items. + * \par + * \code + * #include <cub/cub.cuh> // or equivalently <cub/device/device_radix_sort.cuh> + * + * // Declare, allocate, and initialize device pointers for input and output + * int num_items; // e.g., 7 + * int *d_in; // e.g., [8, 6, 7, 5, 3, 0, 9] + * int *d_out; // e.g., [ ] + * ... + * + * // Determine temporary device storage requirements + * void *d_temp_storage = NULL; + * size_t temp_storage_bytes = 0; + * cub::DeviceReduce::Sum(d_temp_storage, temp_storage_bytes, d_in, d_sum, num_items); + * + * // Allocate temporary storage + * cudaMalloc(&d_temp_storage, temp_storage_bytes); + * + * // Run sum-reduction + * cub::DeviceReduce::Sum(d_temp_storage, temp_storage_bytes, d_in, d_sum, num_items); + * + * // d_out <-- [38] + * + * \endcode + * + * \tparam InputIterator <b>[inferred]</b> Random-access input iterator type for reading input items \iterator + * \tparam OutputIterator <b>[inferred]</b> Output iterator type for recording the reduced aggregate \iterator + */ + template < + typename InputIterator, + typename OutputIterator> + CUB_RUNTIME_FUNCTION + static cudaError_t Sum( + void *d_temp_storage, ///< [in] %Device allocation of temporary storage. When NULL, the required allocation size is written to \p temp_storage_bytes and no work is done. + size_t &temp_storage_bytes, ///< [in,out] Reference to size in bytes of \p d_temp_storage allocation + InputIterator d_in, ///< [in] Pointer to the input sequence of data items + OutputIterator d_out, ///< [out] Pointer to the output aggregate + int num_items, ///< [in] Total number of input items (i.e., length of \p d_in) + cudaStream_t stream = 0, ///< [in] <b>[optional]</b> CUDA stream to launch kernels within. Default is stream<sub>0</sub>. + bool debug_synchronous = false) ///< [in] <b>[optional]</b> Whether or not to synchronize the stream after every kernel launch to check for errors. Also causes launch configurations to be printed to the console. Default is \p false. + { + // Signed integer type for global offsets + typedef int Offset; + + // Dispatch type + typedef DeviceReduceDispatch<InputIterator, OutputIterator, Offset, cub::Sum> DeviceReduceDispatch; + + return DeviceReduceDispatch::Dispatch( + d_temp_storage, + temp_storage_bytes, + d_in, + d_out, + num_items, + cub::Sum(), + stream, + debug_synchronous); + } + + + /** + * \brief Computes a device-wide minimum using the less-than ('<') operator. + * + * \par + * - Does not support non-commutative minimum operators. + * - \devicestorage + * - \cdp + * + * \par Performance + * Performance is typically similar to DeviceReduce::Sum. + * + * \par Snippet + * The code snippet below illustrates the min-reduction of a device vector of \p int items. + * \par + * \code + * #include <cub/cub.cuh> // or equivalently <cub/device/device_radix_sort.cuh> + * + * // Declare, allocate, and initialize device pointers for input and output + * int num_items; // e.g., 7 + * int *d_in; // e.g., [8, 6, 7, 5, 3, 0, 9] + * int *d_out; // e.g., [ ] + * ... + * + * // Determine temporary device storage requirements + * void *d_temp_storage = NULL; + * size_t temp_storage_bytes = 0; + * cub::DeviceReduce::Min(d_temp_storage, temp_storage_bytes, d_in, d_min, num_items); + * + * // Allocate temporary storage + * cudaMalloc(&d_temp_storage, temp_storage_bytes); + * + * // Run min-reduction + * cub::DeviceReduce::Min(d_temp_storage, temp_storage_bytes, d_in, d_min, num_items); + * + * // d_out <-- [0] + * + * \endcode + * + * \tparam InputIterator <b>[inferred]</b> Random-access input iterator type for reading input items \iterator + * \tparam OutputIterator <b>[inferred]</b> Output iterator type for recording the reduced aggregate \iterator + */ + template < + typename InputIterator, + typename OutputIterator> + CUB_RUNTIME_FUNCTION + static cudaError_t Min( + void *d_temp_storage, ///< [in] %Device allocation of temporary storage. When NULL, the required allocation size is written to \p temp_storage_bytes and no work is done. + size_t &temp_storage_bytes, ///< [in,out] Reference to size in bytes of \p d_temp_storage allocation + InputIterator d_in, ///< [in] Pointer to the input sequence of data items + OutputIterator d_out, ///< [out] Pointer to the output aggregate + int num_items, ///< [in] Total number of input items (i.e., length of \p d_in) + cudaStream_t stream = 0, ///< [in] <b>[optional]</b> CUDA stream to launch kernels within. Default is stream<sub>0</sub>. + bool debug_synchronous = false) ///< [in] <b>[optional]</b> Whether or not to synchronize the stream after every kernel launch to check for errors. Also causes launch configurations to be printed to the console. Default is \p false. + { + // Signed integer type for global offsets + typedef int Offset; + + // Dispatch type + typedef DeviceReduceDispatch<InputIterator, OutputIterator, Offset, cub::Min> DeviceReduceDispatch; + + return DeviceReduceDispatch::Dispatch( + d_temp_storage, + temp_storage_bytes, + d_in, + d_out, + num_items, + cub::Min(), + stream, + debug_synchronous); + } + + + /** + * \brief Finds the first device-wide minimum using the less-than ('<') operator, also returning the index of that item. + * + * \par + * Assuming the input \p d_in has value type \p T, the output \p d_out must have value type + * <tt>ItemOffsetPair<T, int></tt>. The minimum value is written to <tt>d_out.value</tt> and its + * location in the input array is written to <tt>d_out.offset</tt>. + * + * \par + * - Does not support non-commutative minimum operators. + * - \devicestorage + * - \cdp + * + * \par Performance + * Performance is typically similar to DeviceReduce::Sum. + * + * \par Snippet + * The code snippet below illustrates the argmin-reduction of a device vector of \p int items. + * \par + * \code + * #include <cub/cub.cuh> // or equivalently <cub/device/device_radix_sort.cuh> + * + * // Declare, allocate, and initialize device pointers for input and output + * int num_items; // e.g., 7 + * int *d_in; // e.g., [8, 6, 7, 5, 3, 0, 9] + * ItemOffsetPair<int, int> *d_out; // e.g., [{ , }] + * ... + * + * // Determine temporary device storage requirements + * void *d_temp_storage = NULL; + * size_t temp_storage_bytes = 0; + * cub::DeviceReduce::ArgMin(d_temp_storage, temp_storage_bytes, d_in, d_argmin, num_items); + * + * // Allocate temporary storage + * cudaMalloc(&d_temp_storage, temp_storage_bytes); + * + * // Run argmin-reduction + * cub::DeviceReduce::ArgMin(d_temp_storage, temp_storage_bytes, d_in, d_argmin, num_items); + * + * // d_out <-- [{0, 5}] + * + * \endcode + * + * \tparam InputIterator <b>[inferred]</b> Random-access input iterator type for reading input items (of some type \p T) \iterator + * \tparam OutputIterator <b>[inferred]</b> Output iterator type for recording the reduced aggregate (having value type <tt>ItemOffsetPair<T, int></tt>) \iterator + */ + template < + typename InputIterator, + typename OutputIterator> + CUB_RUNTIME_FUNCTION + static cudaError_t ArgMin( + void *d_temp_storage, ///< [in] %Device allocation of temporary storage. When NULL, the required allocation size is written to \p temp_storage_bytes and no work is done. + size_t &temp_storage_bytes, ///< [in,out] Reference to size in bytes of \p d_temp_storage allocation + InputIterator d_in, ///< [in] Pointer to the input sequence of data items + OutputIterator d_out, ///< [out] Pointer to the output aggregate + int num_items, ///< [in] Total number of input items (i.e., length of \p d_in) + cudaStream_t stream = 0, ///< [in] <b>[optional]</b> CUDA stream to launch kernels within. Default is stream<sub>0</sub>. + bool debug_synchronous = false) ///< [in] <b>[optional]</b> Whether or not to synchronize the stream after every kernel launch to check for errors. Also causes launch configurations to be printed to the console. Default is \p false. + { + // Signed integer type for global offsets + typedef int Offset; + + // Wrapped input iterator + typedef ArgIndexInputIterator<InputIterator, int> ArgIndexInputIterator; + ArgIndexInputIterator d_argmin_in(d_in, 0); + + // Dispatch type + typedef DeviceReduceDispatch<ArgIndexInputIterator, OutputIterator, Offset, cub::ArgMin> DeviceReduceDispatch; + + return DeviceReduceDispatch::Dispatch( + d_temp_storage, + temp_storage_bytes, + d_argmin_in, + d_out, + num_items, + cub::ArgMin(), + stream, + debug_synchronous); + } + + + /** + * \brief Computes a device-wide maximum using the greater-than ('>') operator. + * + * \par + * - Does not support non-commutative maximum operators. + * - \devicestorage + * - \cdp + * + * \par Performance + * Performance is typically similar to DeviceReduce::Sum. + * + * \par Snippet + * The code snippet below illustrates the max-reduction of a device vector of \p int items. + * \par + * \code + * #include <cub/cub.cuh> // or equivalently <cub/device/device_radix_sort.cuh> + * + * // Declare, allocate, and initialize device pointers for input and output + * int num_items; // e.g., 7 + * int *d_in; // e.g., [8, 6, 7, 5, 3, 0, 9] + * int *d_out; // e.g., [ ] + * ... + * + * // Determine temporary device storage requirements + * void *d_temp_storage = NULL; + * size_t temp_storage_bytes = 0; + * cub::DeviceReduce::Max(d_temp_storage, temp_storage_bytes, d_in, d_max, num_items); + * + * // Allocate temporary storage + * cudaMalloc(&d_temp_storage, temp_storage_bytes); + * + * // Run max-reduction + * cub::DeviceReduce::Max(d_temp_storage, temp_storage_bytes, d_in, d_max, num_items); + * + * // d_out <-- [9] + * + * \endcode + * + * \tparam InputIterator <b>[inferred]</b> Random-access input iterator type for reading input items \iterator + * \tparam OutputIterator <b>[inferred]</b> Output iterator type for recording the reduced aggregate \iterator + */ + template < + typename InputIterator, + typename OutputIterator> + CUB_RUNTIME_FUNCTION + static cudaError_t Max( + void *d_temp_storage, ///< [in] %Device allocation of temporary storage. When NULL, the required allocation size is written to \p temp_storage_bytes and no work is done. + size_t &temp_storage_bytes, ///< [in,out] Reference to size in bytes of \p d_temp_storage allocation + InputIterator d_in, ///< [in] Pointer to the input sequence of data items + OutputIterator d_out, ///< [out] Pointer to the output aggregate + int num_items, ///< [in] Total number of input items (i.e., length of \p d_in) + cudaStream_t stream = 0, ///< [in] <b>[optional]</b> CUDA stream to launch kernels within. Default is stream<sub>0</sub>. + bool debug_synchronous = false) ///< [in] <b>[optional]</b> Whether or not to synchronize the stream after every kernel launch to check for errors. Also causes launch configurations to be printed to the console. Default is \p false. + { + // Signed integer type for global offsets + typedef int Offset; + + // Dispatch type + typedef DeviceReduceDispatch<InputIterator, OutputIterator, Offset, cub::Max> DeviceReduceDispatch; + + return DeviceReduceDispatch::Dispatch( + d_temp_storage, + temp_storage_bytes, + d_in, + d_out, + num_items, + cub::Max(), + stream, + debug_synchronous); + } + + + /** + * \brief Finds the first device-wide maximum using the greater-than ('>') operator, also returning the index of that item + * + * \par + * Assuming the input \p d_in has value type \p T, the output \p d_out must have value type + * <tt>ItemOffsetPair<T, int></tt>. The maximum value is written to <tt>d_out.value</tt> and its + * location in the input array is written to <tt>d_out.offset</tt>. + * + * \par + * - Does not support non-commutative maximum operators. + * - \devicestorage + * - \cdp + * + * \par Performance + * Performance is typically similar to DeviceReduce::Sum. + * + * \par Snippet + * The code snippet below illustrates the argmax-reduction of a device vector of \p int items. + * \par + * \code + * #include <cub/cub.cuh> // or equivalently <cub/device/device_reduce.cuh> + * + * // Declare, allocate, and initialize device pointers for input and output + * int num_items; // e.g., 7 + * int *d_in; // e.g., [8, 6, 7, 5, 3, 0, 9] + * ItemOffsetPair<int, int> *d_out; // e.g., [{ , }] + * ... + * + * // Determine temporary device storage requirements + * void *d_temp_storage = NULL; + * size_t temp_storage_bytes = 0; + * cub::DeviceReduce::ArgMax(d_temp_storage, temp_storage_bytes, d_in, d_argmax, num_items); + * + * // Allocate temporary storage + * cudaMalloc(&d_temp_storage, temp_storage_bytes); + * + * // Run argmax-reduction + * cub::DeviceReduce::ArgMax(d_temp_storage, temp_storage_bytes, d_in, d_argmax, num_items); + * + * // d_out <-- [{9, 6}] + * + * \endcode + * + * \tparam InputIterator <b>[inferred]</b> Random-access input iterator type for reading input items (of some type \p T) \iterator + * \tparam OutputIterator <b>[inferred]</b> Output iterator type for recording the reduced aggregate (having value type <tt>ItemOffsetPair<T, int></tt>) \iterator + */ + template < + typename InputIterator, + typename OutputIterator> + CUB_RUNTIME_FUNCTION + static cudaError_t ArgMax( + void *d_temp_storage, ///< [in] %Device allocation of temporary storage. When NULL, the required allocation size is written to \p temp_storage_bytes and no work is done. + size_t &temp_storage_bytes, ///< [in,out] Reference to size in bytes of \p d_temp_storage allocation + InputIterator d_in, ///< [in] Pointer to the input sequence of data items + OutputIterator d_out, ///< [out] Pointer to the output aggregate + int num_items, ///< [in] Total number of input items (i.e., length of \p d_in) + cudaStream_t stream = 0, ///< [in] <b>[optional]</b> CUDA stream to launch kernels within. Default is stream<sub>0</sub>. + bool debug_synchronous = false) ///< [in] <b>[optional]</b> Whether or not to synchronize the stream after every kernel launch to check for errors. Also causes launch configurations to be printed to the console. Default is \p false. + { + // Signed integer type for global offsets + typedef int Offset; + + // Wrapped input iterator + typedef ArgIndexInputIterator<InputIterator, int> ArgIndexInputIterator; + ArgIndexInputIterator d_argmax_in(d_in, 0); + + // Dispatch type + typedef DeviceReduceDispatch<ArgIndexInputIterator, OutputIterator, Offset, cub::ArgMax> DeviceReduceDispatch; + + return DeviceReduceDispatch::Dispatch( + d_temp_storage, + temp_storage_bytes, + d_argmax_in, + d_out, + num_items, + cub::ArgMax(), + stream, + debug_synchronous); + } + + + /** + * \brief Reduces segments of values, where segments are demarcated by corresponding runs of identical keys. + * + * \par + * This operation computes segmented reductions using the specified binary + * \p reduction_op functor. Each "run" of consecutive, identical keys in \p d_keys_in + * is used to identify a corresponding segment of values in \p d_values_in. The first key in + * the <em>i</em><sup>th</sup> segment is copied to <tt>d_keys_out[<em>i</em>]</tt>, and + * the value aggregate for that segment is written to <tt>d_values_out[<em>i</em>]</tt>. + * The total number of segments discovered is written to \p d_num_segments. + * + * \par + * - The <tt>==</tt> equality operator is used to determine whether keys are equivalent + * - \devicestorage + * - \cdp + * + * \par Performance + * The following chart illustrates reduction-by-key (sum) performance across + * different CUDA architectures for \p fp32 and \p fp64 values, respectively. Segments + * are identified by \p int32 keys, and have lengths uniformly sampled from [1,1000]. + * + * \image html reduce_by_key_fp32_len_500.png + * \image html reduce_by_key_fp64_len_500.png + * + * \par + * The following charts are similar, but with segment lengths uniformly sampled from [1,10]: + * + * \image html reduce_by_key_fp32_len_5.png + * \image html reduce_by_key_fp64_len_5.png + * + * \par Snippet + * The code snippet below illustrates the segmented reduction of \p int values grouped + * by runs of associated \p int keys. + * \par + * \code + * #include <cub/cub.cuh> // or equivalently <cub/device/device_reduce.cuh> + * + * // CustomMin functor + * struct CustomMin + * { + * template <typename T> + * CUB_RUNTIME_FUNCTION __forceinline__ + * T operator()(const T &a, const T &b) const { + * return (b < a) ? b : a; + * } + * }; + * + * // Declare, allocate, and initialize device pointers for input and output + * int num_items; // e.g., 8 + * int *d_keys_in; // e.g., [0, 2, 2, 9, 5, 5, 5, 8] + * int *d_values_in; // e.g., [0, 7, 1, 6, 2, 5, 3, 4] + * int *d_keys_out; // e.g., [ , , , , , , , ] + * int *d_values_out; // e.g., [ , , , , , , , ] + * int *d_num_segments; // e.g., [ ] + * CustomMin reduction_op; + * ... + * + * // Determine temporary device storage requirements + * void *d_temp_storage = NULL; + * size_t temp_storage_bytes = 0; + * cub::DeviceReduce::ReduceByKey(d_temp_storage, temp_storage_bytes, d_keys_in, d_keys_out, d_values_in, d_values_out, d_num_segments, reduction_op, num_items); + * + * // Allocate temporary storage + * cudaMalloc(&d_temp_storage, temp_storage_bytes); + * + * // Run reduce-by-key + * cub::DeviceReduce::ReduceByKey(d_temp_storage, temp_storage_bytes, d_keys_in, d_keys_out, d_values_in, d_values_out, d_num_segments, reduction_op, num_items); + * + * // d_keys_out <-- [0, 2, 9, 5, 8] + * // d_values_out <-- [0, 1, 6, 2, 4] + * // d_num_segments <-- [5] + * + * \endcode + * + * \tparam KeyInputIterator <b>[inferred]</b> Random-access input iterator type for reading input keys \iterator + * \tparam KeyOutputIterator <b>[inferred]</b> Random-access output iterator type for writing output keys \iterator + * \tparam ValueInputIterator <b>[inferred]</b> Random-access input iterator type for reading input values \iterator + * \tparam ValueOutputIterator <b>[inferred]</b> Random-access output iterator type for writing output values \iterator + * \tparam NumSegmentsIterator <b>[inferred]</b> Output iterator type for recording the number of segments encountered \iterator + * \tparam ReductionOp <b>[inferred]</b> Binary reduction functor type having member <tt>T operator()(const T &a, const T &b)</tt> + */ + template < + typename KeyInputIterator, + typename KeyOutputIterator, + typename ValueInputIterator, + typename ValueOutputIterator, + typename NumSegmentsIterator, + typename ReductionOp> + CUB_RUNTIME_FUNCTION __forceinline__ + static cudaError_t ReduceByKey( + void *d_temp_storage, ///< [in] %Device allocation of temporary storage. When NULL, the required allocation size is written to \p temp_storage_bytes and no work is done. + size_t &temp_storage_bytes, ///< [in,out] Reference to size in bytes of \p d_temp_storage allocation + KeyInputIterator d_keys_in, ///< [in] Pointer to consecutive runs of input keys + KeyOutputIterator d_keys_out, ///< [out] Pointer to output keys (one key per run) + ValueInputIterator d_values_in, ///< [in] Pointer to consecutive runs of input values + ValueOutputIterator d_values_out, ///< [out] Pointer to output value aggregates (one aggregate per run) + NumSegmentsIterator d_num_segments, ///< [out] Pointer to total number of segments + ReductionOp reduction_op, ///< [in] Binary reduction functor (e.g., an instance of cub::Sum, cub::Min, cub::Max, etc.) + int num_items, ///< [in] Total number of associated key+value pairs (i.e., the length of \p d_in_keys and \p d_in_values) + cudaStream_t stream = 0, ///< [in] <b>[optional]</b> CUDA stream to launch kernels within. Default is stream<sub>0</sub>. + bool debug_synchronous = false) ///< [in] <b>[optional]</b> Whether or not to synchronize the stream after every kernel launch to check for errors. May cause significant slowdown. Default is \p false. + { + typedef int Offset; // Signed integer type for global offsets + typedef NullType* FlagIterator; // Flag iterator type (not used) + typedef NullType SelectOp; // Selection op (not used) + typedef Equality EqualityOp; // Default == operator + + return DeviceReduceByKeyDispatch<KeyInputIterator, KeyOutputIterator, ValueInputIterator, ValueOutputIterator, NumSegmentsIterator, EqualityOp, ReductionOp, Offset>::Dispatch( + d_temp_storage, + temp_storage_bytes, + d_keys_in, + d_keys_out, + d_values_in, + d_values_out, + d_num_segments, + EqualityOp(), + reduction_op, + num_items, + stream, + debug_synchronous); + } + + + /** + * \brief Counts the segment lengths in the sequence \p d_in, where segments are demarcated by runs of identical values. + * + * \par + * This operation computes a run-length encoding of \p d_in, where segments are identified + * by "runs" of consecutive, identical values. The length of the <em>i</em><sup>th</sup> segment + * is written to <tt>d_counts_out[<em>i</em>]</tt>. The unique values are also compacted, + * i.e., the first value in the <em>i</em><sup>th</sup> segment is copied to + * <tt>d_compacted_out[<em>i</em>]</tt>. The total number of segments discovered is written + * to \p d_num_segments. + * + * \par + * - The <tt>==</tt> equality operator is used to determine whether values are equivalent + * - \devicestorage + * - \cdp + * + * \par Performance + * The following charts illustrate saturated encode performance across different + * CUDA architectures for \p int32 and \p int64 items, respectively. Segments have + * lengths uniformly sampled from [1,1000]. + * + * \image html rle_int32_len_500.png + * \image html rle_int64_len_500.png + * + * \par + * The following charts are similar, but with segment lengths uniformly sampled from [1,10]: + * + * \image html rle_int32_len_5.png + * \image html rle_int64_len_5.png + * + * \par Snippet + * The code snippet below illustrates the run-length encoding of a sequence of \p int values. + * \par + * \code + * #include <cub/cub.cuh> // or equivalently <cub/device/device_reduce.cuh> + * + * // Declare, allocate, and initialize device pointers for input and output + * int num_items; // e.g., 8 + * int *d_in; // e.g., [0, 2, 2, 9, 5, 5, 5, 8] + * int *d_compacted_out; // e.g., [ , , , , , , , ] + * int *d_counts_out; // e.g., [ , , , , , , , ] + * int *d_num_segments; // e.g., [ ] + * ... + * + * // Determine temporary device storage requirements + * void *d_temp_storage = NULL; + * size_t temp_storage_bytes = 0; + * cub::DeviceReduce::RunLengthEncode(d_temp_storage, temp_storage_bytes, d_in, d_compacted_out, d_counts_out, d_num_segments, num_items); + * + * // Allocate temporary storage + * cudaMalloc(&d_temp_storage, temp_storage_bytes); + * + * // Run encoding + * cub::DeviceReduce::RunLengthEncode(d_temp_storage, temp_storage_bytes, d_in, d_compacted_out, d_counts_out, d_num_segments, num_items); + * + * // d_keys_out <-- [0, 2, 9, 5, 8] + * // d_values_out <-- [1, 2, 1, 3, 1] + * // d_num_segments <-- [5] + * + * \endcode + * + * \tparam InputIterator <b>[inferred]</b> Random-access input iterator type for reading input items \iterator + * \tparam OutputIterator <b>[inferred]</b> Random-access output iterator type for writing compacted output items \iterator + * \tparam CountsOutputIterator <b>[inferred]</b> Random-access output iterator type for writing output counts \iterator + * \tparam NumSegmentsIterator <b>[inferred]</b> Output iterator type for recording the number of segments encountered \iterator + */ + template < + typename InputIterator, + typename OutputIterator, + typename CountsOutputIterator, + typename NumSegmentsIterator> + CUB_RUNTIME_FUNCTION __forceinline__ + static cudaError_t RunLengthEncode( + void *d_temp_storage, ///< [in] %Device allocation of temporary storage. When NULL, the required allocation size is written to \p temp_storage_bytes and no work is done. + size_t &temp_storage_bytes, ///< [in,out] Reference to size in bytes of \p d_temp_storage allocation + InputIterator d_in, ///< [in] Pointer to consecutive runs of input keys + OutputIterator d_compacted_out, ///< [out] Pointer to output keys (one key per run) + CountsOutputIterator d_counts_out, ///< [out] Pointer to output value aggregates (one aggregate per run) + NumSegmentsIterator d_num_segments, ///< [out] Pointer to total number of segments + int num_items, ///< [in] Total number of associated key+value pairs (i.e., the length of \p d_in_keys and \p d_in_values) + cudaStream_t stream = 0, ///< [in] <b>[optional]</b> CUDA stream to launch kernels within. Default is stream<sub>0</sub>. + bool debug_synchronous = false) ///< [in] <b>[optional]</b> Whether or not to synchronize the stream after every kernel launch to check for errors. May cause significant slowdown. Default is \p false. + { + // Data type of value iterator + typedef typename std::iterator_traits<CountsOutputIterator>::value_type Value; + + typedef int Offset; // Signed integer type for global offsets + typedef NullType* FlagIterator; // Flag iterator type (not used) + typedef NullType SelectOp; // Selection op (not used) + typedef Equality EqualityOp; // Default == operator + typedef cub::Sum ReductionOp; // Value reduction operator + + // Generator type for providing 1s values for run-length reduction + typedef ConstantInputIterator<Value, Offset> CountsInputIterator; + + Value one_val; + one_val = 1; + + return DeviceReduceByKeyDispatch<InputIterator, OutputIterator, CountsInputIterator, CountsOutputIterator, NumSegmentsIterator, EqualityOp, ReductionOp, Offset>::Dispatch( + d_temp_storage, + temp_storage_bytes, + d_in, + d_compacted_out, + CountsInputIterator(one_val), + d_counts_out, + d_num_segments, + EqualityOp(), + ReductionOp(), + num_items, + stream, + debug_synchronous); + } + +}; + +/** + * \example example_device_reduce.cu + */ + +} // CUB namespace +CUB_NS_POSTFIX // Optional outer namespace(s) + + |