Function opt_n_threads

pointops2/src/cuda_utils.h:11–14

#define DIVUP(m, n) ((m) / (n) + ((m) % (n) > 0))

inline int opt_n_threads(int work_size) {
    const int pow_2 = std::log(static_cast<double>(work_size)) / std::log(2.0);
    return std::max(std::min(1 << pow_2, TOTAL_THREADS), 1);
}

inline dim3 opt_block_config(int x, int y) {
    const int x_threads = opt_n_threads(x);