Game Engine Architecture 6

【Game Engine Architecture 6】

1、Data-Parallel Computations

　　A GPU is a specialized coprocessor designed specifically to accelerate those computations that involve a high degree of data parallelism. It does so by combining SIMD parallelism (vectorized ALUs) with MIMD parallelism (by employing a form of preemptive multithreading). NVIDIA coined the term single instruction multiple thread (SIMT) to describe this SIMD/MIMD hybrid design, all GPUs employ the general principles of SIMT parallelism in their designs.

　　In order for a computational task to be well-suited to execution on a GPU,  the computations performed on any one element of the dataset must be independent of the results of computations on other elements.

void DotArrays_ref(unsigned count,
                    float r[],
                    const float a[],
                    const float b[])
{
    for (unsigned i = 0; i < count; ++i)
    {
        // treat each block of four floats as a
        // single four-element vector
        const unsigned j = i * 4;
        r[i] = a[j+0]*b[j+0] // ax*bx
                + a[j+1]*b[j+1] // ay*by
                + a[j+2]*b[j+2] // az*bz
                + a[j+3]*b[j+3]; // aw*bw
    }
}

View Code