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xgboost/cub/cub/block/block_load.cuh  view on Meta::CPAN

    /**
     * \par Overview
     *
     * A [<em>striped arrangement</em>](index.html#sec5sec3) of data is read
     * efficiently from memory and then locally transposed into a
     * [<em>blocked arrangement</em>](index.html#sec5sec3).
     *
     * \par Performance Considerations
     * - The utilization of memory transactions (coalescing) remains high regardless
     *   of items loaded per thread.
     * - The local reordering incurs slightly longer latencies and throughput than the
     *   direct cub::BLOCK_LOAD_DIRECT and cub::BLOCK_LOAD_VECTORIZE alternatives.
     */
    BLOCK_LOAD_TRANSPOSE,


    /**
     * \par Overview
     *
     * A [<em>warp-striped arrangement</em>](index.html#sec5sec3) of data is
     * read efficiently from memory and then locally transposed into a
     * [<em>blocked arrangement</em>](index.html#sec5sec3).
     *
     * \par Usage Considerations
     * - BLOCK_THREADS must be a multiple of WARP_THREADS
     *
     * \par Performance Considerations
     * - The utilization of memory transactions (coalescing) remains high regardless
     *   of items loaded per thread.
     * - The local reordering incurs slightly larger latencies than the
     *   direct cub::BLOCK_LOAD_DIRECT and cub::BLOCK_LOAD_VECTORIZE alternatives.
     * - Provisions more shared storage, but incurs smaller latencies than the
     *   BLOCK_LOAD_WARP_TRANSPOSE_TIMESLICED alternative.
     */
    BLOCK_LOAD_WARP_TRANSPOSE,


    /**
     * \par Overview
     *
     * Like \p BLOCK_LOAD_WARP_TRANSPOSE, a [<em>warp-striped arrangement</em>](index.html#sec5sec3)
     * of data is read directly from memory and then is locally transposed into a
     * [<em>blocked arrangement</em>](index.html#sec5sec3). To reduce the shared memory
     * requirement, only one warp's worth of shared memory is provisioned and is
     * subsequently time-sliced among warps.
     *
     * \par Usage Considerations
     * - BLOCK_THREADS must be a multiple of WARP_THREADS
     *
     * \par Performance Considerations
     * - The utilization of memory transactions (coalescing) remains high regardless
     *   of items loaded per thread.
     * - Provisions less shared memory temporary storage, but incurs larger
     *   latencies than the BLOCK_LOAD_WARP_TRANSPOSE alternative.
     */
    BLOCK_LOAD_WARP_TRANSPOSE_TIMESLICED,
};


/**
 * \brief The BlockLoad class provides [<em>collective</em>](index.html#sec0) data movement methods for loading a linear segment of items from memory into a [<em>blocked arrangement</em>](index.html#sec5sec3) across a CUDA thread block.  ![](block_lo...
 * \ingroup BlockModule
 * \ingroup UtilIo
 *
 * \tparam InputT               The data type to read into (which must be convertible from the input iterator's value type).
 * \tparam BLOCK_DIM_X          The thread block length in threads along the X dimension
 * \tparam ITEMS_PER_THREAD     The number of consecutive items partitioned onto each thread.
 * \tparam ALGORITHM            <b>[optional]</b> cub::BlockLoadAlgorithm tuning policy.  default: cub::BLOCK_LOAD_DIRECT.
 * \tparam WARP_TIME_SLICING    <b>[optional]</b> Whether or not only one warp's worth of shared memory should be allocated and time-sliced among block-warps during any load-related data transpositions (versus each warp having its own storage). (defa...
 * \tparam BLOCK_DIM_Y          <b>[optional]</b> The thread block length in threads along the Y dimension (default: 1)
 * \tparam BLOCK_DIM_Z          <b>[optional]</b> The thread block length in threads along the Z dimension (default: 1)
 * \tparam PTX_ARCH             <b>[optional]</b> \ptxversion
 *
 * \par Overview
 * - The BlockLoad class provides a single data movement abstraction that can be specialized
 *   to implement different cub::BlockLoadAlgorithm strategies.  This facilitates different
 *   performance policies for different architectures, data types, granularity sizes, etc.
 * - BlockLoad can be optionally specialized by different data movement strategies:
 *   -# <b>cub::BLOCK_LOAD_DIRECT</b>.  A [<em>blocked arrangement</em>](index.html#sec5sec3)
 *      of data is read directly from memory.  [More...](\ref cub::BlockLoadAlgorithm)
 *   -# <b>cub::BLOCK_LOAD_VECTORIZE</b>.  A [<em>blocked arrangement</em>](index.html#sec5sec3)
 *      of data is read directly from memory using CUDA's built-in vectorized loads as a
 *      coalescing optimization.    [More...](\ref cub::BlockLoadAlgorithm)
 *   -# <b>cub::BLOCK_LOAD_TRANSPOSE</b>.  A [<em>striped arrangement</em>](index.html#sec5sec3)
 *      of data is read directly from memory and is then locally transposed into a
 *      [<em>blocked arrangement</em>](index.html#sec5sec3).  [More...](\ref cub::BlockLoadAlgorithm)
 *   -# <b>cub::BLOCK_LOAD_WARP_TRANSPOSE</b>.  A [<em>warp-striped arrangement</em>](index.html#sec5sec3)
 *      of data is read directly from memory and is then locally transposed into a
 *      [<em>blocked arrangement</em>](index.html#sec5sec3).  [More...](\ref cub::BlockLoadAlgorithm)
 *   -# <b>cub::BLOCK_LOAD_WARP_TRANSPOSE_TIMESLICED,</b>.  A [<em>warp-striped arrangement</em>](index.html#sec5sec3)
 *      of data is read directly from memory and is then locally transposed into a
 *      [<em>blocked arrangement</em>](index.html#sec5sec3) one warp at a time.  [More...](\ref cub::BlockLoadAlgorithm)
 * - \rowmajor
 *
 * \par A Simple Example
 * \blockcollective{BlockLoad}
 * \par
 * The code snippet below illustrates the loading of a linear
 * segment of 512 integers into a "blocked" arrangement across 128 threads where each
 * thread owns 4 consecutive items.  The load is specialized for \p BLOCK_LOAD_WARP_TRANSPOSE,
 * meaning memory references are efficiently coalesced using a warp-striped access
 * pattern (after which items are locally reordered among threads).
 * \par
 * \code
 * #include <cub/cub.cuh>   // or equivalently <cub/block/block_load.cuh>
 *
 * __global__ void ExampleKernel(int *d_data, ...)
 * {
 *     // Specialize BlockLoad for a 1D block of 128 threads owning 4 integer items each
 *     typedef cub::BlockLoad<int, 128, 4, BLOCK_LOAD_WARP_TRANSPOSE> BlockLoad;
 *
 *     // Allocate shared memory for BlockLoad
 *     __shared__ typename BlockLoad::TempStorage temp_storage;
 *
 *     // Load a segment of consecutive items that are blocked across threads
 *     int thread_data[4];
 *     BlockLoad(temp_storage).Load(d_data, thread_data);
 *
 * \endcode
 * \par
 * Suppose the input \p d_data is <tt>0, 1, 2, 3, 4, 5, ...</tt>.



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