Question

我正在尝试在CUDA中使用CuRand库。我只想简单地尝试为每个线程生成一个随机整数。以下是我的结果（显然不是很随机）：

请检查我的代码并告诉我我做错了什么，我试着弄清楚为什么这不起作用......

#include <stdio.h>
#include <stdlib.h>
#include <cuda.h>
#include <curand.h>
#include <curand_kernel.h>

__device__ float generate(curandState* globalState, int ind)
{
    //int ind = threadIdx.x;
    curandState localState = globalState[ind];
    float RANDOM = curand_uniform( &localState );
    globalState[ind] = localState;
    return RANDOM;
}

__global__ void setup_kernel ( curandState * state, unsigned long seed )
{
    int id = threadIdx.x;
    curand_init ( seed, id, 0, &state[id] );
}

__global__ void addToCount(int N, int *y, curandState* globalState)
{
    int id = threadIdx.x + blockIdx.x * blockDim.x;
while (id < N)
{
    int number = generate(globalState, id) * 1000000;
    printf("%i\n", number);

    atomicAdd(&(y[0]), number);
    id += blockDim.x * gridDim.x;
}
}

int main(void)
{
  int N = 5;
  int *y, *d_y;
  y = (int*)malloc(N*sizeof(int));

  cudaMalloc(&d_y, N * sizeof(int));
  cudaMemcpy(d_y, y, N * sizeof(int), cudaMemcpyHostToDevice);

  curandState* devStates;
  cudaMalloc (&devStates, N * sizeof(curandState));

  addToCount<<<2, 5>>>(N, d_y, devStates);

  cudaMemcpy(y, d_y, N*sizeof(int), cudaMemcpyDeviceToHost);
  printf("%i\n", *y);
}

Answer 1

<@> AS @Robert Crovella在评论中提到，你忘了设置内核。在提供实际随机数之前，需要为每个线程初始化curand状态。如果您将main更改为：

int main(void)
{
  int N = 5;
  int *y, *d_y;
  y = (int*)malloc(N*sizeof(int));

  cudaMalloc(&d_y, N * sizeof(int));
  cudaMemcpy(d_y, y, N * sizeof(int), cudaMemcpyHostToDevice);

  curandState* devStates;
  cudaMalloc (&devStates, N * sizeof(curandState));
  srand(time(0));
  /** ADD THESE TWO LINES **/
  int seed = rand();
  setup_kernel<<<2, 5>>>(devStates,seed);
  /** END ADDITION **/
  addToCount<<<2, 5>>>(N, d_y, devStates);

  cudaMemcpy(y, d_y, N*sizeof(int), cudaMemcpyDeviceToHost);
  printf("%i\n", *y);
}

默认编译结果很好：

nvcc /tmp/so.cu -o /tmp/so

$ /tmp/so
900981
469952
494161
31968
880329
2777391
$ /tmp/so
525835
742594
750423
117137
66318
2202307
$ /tmp/so
919262
60838
89868
57696
770764
1898428

在Cuda内核中生成随机数

1 个答案: