Question

是否可以在设备仿函数中使用CURAND和Thrust？最小代码示例可以是：

#include <thrust/device_vector.h>

struct Move
{
    Move() {}

    using Position = thrust::tuple<double, double>;

    __host__ __device__
    Position operator()(Position p)
    {
        thrust::get<0>(p) += 1.0; // use CURAND to add a random N(0,1)
        thrust::get<1>(p) += 1.0; // use CURAND to add a random N(0,1)
        return p;
    }
};

int main()
{
    // Create vectors on device
    thrust::device_vector<double> p1(10, 0.0);
    thrust::device_vector<double> p2(10, 0.0);

    // Create zip iterators
    auto pBeg = thrust::make_zip_iterator(thrust::make_tuple(p1.begin(), p2.begin()));
    auto pEnd = thrust::make_zip_iterator(thrust::make_tuple(p1.end(),   p2.end()  ));

    // Move points in the vectors
    thrust::transform(pBeg, pEnd, pBeg, Move());

    // Print result (just for debug)
    thrust::copy(p1.begin(), p1.end(), std::ostream_iterator<double>(std::cout, "\n"));
    thrust::copy(p2.begin(), p2.end(), std::ostream_iterator<double>(std::cout, "\n"));

    return 0;
}

在运算符函数中创建随机数的正确方法是什么？

Answer 1

Is it possible to use CURAND together with Thrust inside a device functor?

Yes, it's possible. As indicated by @m.s. most of what you need from curand can be gotten from the curand device api example中提取href。（事实上，文档here）中还有完整的推力/文本示例代码

我们可以使用推力算法调用来模拟那里指示的设置内核的行为，例如。 thrust::for_each_n为每个设备向量元素设置初始curand状态变量。

之后，只需要通过zip迭代器中的附加迭代器将初始化的curand状态传递给Move仿函数，然后在仿函数中调用curand_uniform（例如）。 / p>

以下是一个完整的示例，基于您的代码：

$ cat t20.cu
#include <thrust/device_vector.h>
#include <curand_kernel.h>
#include <iostream>
#include <thrust/iterator/counting_iterator.h>
#include <thrust/transform.h>
#include <thrust/for_each.h>

const int seed = 1234;
const int ds = 10;
const int offset = 0;

struct Move
{
    Move() {}

    using Position = thrust::tuple<double, double, curandState>;

    __device__
    Position operator()(Position p)
    {
        curandState s = thrust::get<2>(p);
        thrust::get<0>(p) += curand_uniform(&s); // use CURAND to add a random N(0,1)
        thrust::get<1>(p) += curand_uniform(&s); // use CURAND to add a random N(0,1)
        thrust::get<2>(p) = s;
        return p;
    }
};

struct curand_setup
{
    using init_tuple = thrust::tuple<int, curandState &>;
    __device__
    void operator()(init_tuple t){
      curandState s;
      int id = thrust::get<0>(t);
      curand_init(seed, id, offset, &s);
      thrust::get<1>(t) = s;
      }
};

int main()
{
    // Create vectors on device
    thrust::device_vector<double> p1(ds, 0.0);
    thrust::device_vector<double> p2(ds, 0.0);
    thrust::device_vector<curandState> s1(ds);

    // Create zip iterators
    auto pBeg = thrust::make_zip_iterator(thrust::make_tuple(p1.begin(), p2.begin(), s1.begin()));
    auto pEnd = thrust::make_zip_iterator(thrust::make_tuple(p1.end(),   p2.end(), s1.end()  ));
    auto pInit = thrust::make_zip_iterator(thrust::make_tuple(thrust::counting_iterator<int>(0), s1.begin()));
    // initialize random generator
    thrust::for_each_n(pInit, ds, curand_setup());
    // Move points in the vectors
    thrust::transform(pBeg, pEnd, pBeg, Move());

    // Print result (just for debug)
    thrust::copy(p1.begin(), p1.end(), std::ostream_iterator<double>(std::cout, "\n"));
    thrust::copy(p2.begin(), p2.end(), std::ostream_iterator<double>(std::cout, "\n"));

    return 0;
}
$ nvcc -arch=sm_61 -std=c++11 t20.cu -o t20 -lcurand
$ ./t20
0.145468
0.820181
0.550399
0.29483
0.914733
0.868979
0.321921
0.782857
0.0113023
0.28545
0.434899
0.926417
0.811845
0.308556
0.557235
0.501246
0.206681
0.123377
0.539587
0.198575
$

关于这个问题：

在运算符函数中创建随机数的正确方法是什么？

在推力中使用curand没有问题，但你可能也想知道推力有内置RNG facility并且有一个完整的用法示例here。

在Thrust仿函数中使用CURAND

1 个答案: