starpu-max/doc/chapters/vector_scal_cuda.texi

@c -*-texinfo-*-

@c This file is part of the StarPU Handbook.
@c Copyright (C) 2009-2011  Université de Bordeaux 1
@c Copyright (C) 2010, 2011  Centre National de la Recherche Scientifique
@c See the file starpu.texi for copying conditions.

@smallexample
#include <starpu.h>
#include <starpu_cuda.h>

static __global__ void vector_mult_cuda(float *val, unsigned n,
                                        float factor)
@{
        unsigned i =  blockIdx.x*blockDim.x + threadIdx.x;
        if (i < n)
               val[i] *= factor;
@}

extern "C" void scal_cuda_func(void *buffers[], void *_args)
@{
        float *factor = (float *)_args;

        /* length of the vector */
        unsigned n = STARPU_VECTOR_GET_NX(buffers[0]);
        /* local copy of the vector pointer */
        float *val = (float *)STARPU_VECTOR_GET_PTR(buffers[0]);
        unsigned threads_per_block = 64;
        unsigned nblocks = (n + threads_per_block-1) / threads_per_block;

        vector_mult_cuda<<<nblocks,threads_per_block, 0, starpu_cuda_get_local_stream()>>>(val, n, *factor);

        cudaStreamSynchronize(starpu_cuda_get_local_stream());
@}
@end smallexample