在结构指针传递给CUDA [英] Pointers in structs passed to CUDA

问题描述

我一直在瞎搞与这一段时间，但似乎无法得到它的权利。我试图复制包含数组到CUDA设备内存中的对象（和回来，但我会船到桥头时，我来到它）：

I've been messing around with this for a while now, but can't seem to get it right. I'm trying to copy objects that contain arrays into CUDA device memory (and back again, but I'll cross that bridge when I come to it):

struct MyData {
  float *data;
  int dataLen;
}

void copyToGPU() {
  // Create dummy objects to copy
  int N = 10;
  MyData *h_items = new MyData[N];
  for (int i=0; i<N; i++) {
    h_items[i].dataLen = 100;
    h_items[i].data = new float[100];
  }

  // Copy objects to GPU
  MyData *d_items;
  int memSize = N * sizeof(MyData);
  cudaMalloc((void**)&d_items, memSize);
  cudaMemCpy(d_items, h_items, memSize, cudaMemcpyHostToDevice);

  // Run the kernel
  MyFunc<<<100,100>>>(d_items);
}

__global__
static void MyFunc(MyData *data) {
  int idx = blockIdx.x * blockDim.x + threadIdx.x;
  for (int i=0; i<data[idx].dataLen; i++) {
    // Do something with data[idx].data[i]
  }
}

当我打电话MYFUNC（d_items），我可以访问数据[IDX] .dataLen就好了。然而，数据[idx的]。数据还没有被复制。

When I call MyFunc(d_items), I can access data[idx].dataLen just fine. However, data[idx].data has not been copied yet.

我不能copyToGPU使用d_items.data如由于主机code不能解引用一个设备指针。

I can't use d_items.data in copyToGPU as a destination for cudaMalloc/cudaMemCpy operations since the host code cannot dereference a device pointer.

该怎么办？

推荐答案

• 分配给所有设备数据
  结构，作为一个单一的阵列。


• 复制连续的数据从主机到
  GPU。


• 调整GPU指针

例如：

float *d_data;
cudaMalloc((void**)&d_data, N*100*sizeof(float));
for (...) {
    h_items[i].data = i*100 + d_data;
}

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