cuda - 使用推力的简单排序不起作用

Question

我有一个 cuda 推力程序作为

#include <stdio.h>
#include<iostream>
#include <cuda.h>
#include <thrust/sort.h>



// main routine that executes on the host
int main(void)
{
  int *a_h, *a_d;  // Pointer to host & device arrays
  const int N = 10;  // Number of elements in arrays
  size_t size = N * sizeof(int);
  a_h = (int *)malloc(size);        // Allocate array on host
  cudaMalloc((void **) &a_d, size);// Allocate array on device
  std::cout<<"enter the 10 numbers";
  // Initialize host array and copy it to CUDA device
  for (int i=0; i<N; i++) 
  {
      std::cin>>a_h[i];
  }
  for (int i=0; i<N; i++) printf("%d %d\n", i, a_h[i]);
  cudaMemcpy(a_d, a_h, size, cudaMemcpyHostToDevice);
  thrust::sort(a_d, a_d + N);
  // Do calculation on device:

  cudaMemcpy(a_h, a_d, sizeof(int)*N, cudaMemcpyDeviceToHost);
  // Print results
  for (int i=0; i<N; i++) printf("%d %d\n", i, a_h[i]);
  // Cleanup
  free(a_h); cudaFree(a_d);
} 

但它没有运行以提供所需的输出。

我们应该使用主机向量和设备向量进行推力排序吗？？？？

Answer 1

对于设备操作，您应该使用设备指针或 device_vector 迭代器，而不是原始指针。原始指针(指向主机内存)可用于主机上的操作。

所以如果你修改你的代码如下:

#include <thrust/device_ptr.h>
...
thrust::device_ptr<int> t_a(a_d);  // add this line before the sort line
thrust::sort(t_a, t_a + N);        // modify your sort line

我相信它对你有用。

不妨阅读推力quick start guide .特别注意这一部分:

You may wonder what happens when a "raw" pointer is used as an argument to a Thrust function. Like the STL, Thrust permits this usage and it will dispatch the host path of the algorithm. If the pointer in question is in fact a pointer to device memory then you'll need to wrap it with thrust::device_ptr before calling the function