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authorMiles Macklin <[email protected]>2017-03-10 14:51:31 +1300
committerMiles Macklin <[email protected]>2017-03-10 14:51:31 +1300
commitad3d90fafe5ee79964bdfe1f1e0704c3ffcdfd5f (patch)
tree4cc6f3288363889d7342f7f8407c0251e6904819 /external/cub-1.3.2/cub/device/device_reduce.cuh
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+
+/******************************************************************************
+ * 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. ![](reduce_logo.png)
+ * \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)
+
+