cudaMemcpyFromSymbol和cudaMemcpyToSymbol总是返回cudaErrorInvalidSymbol（13）错误

Question

我在CUDA C ++ API中调用cudaMemcpyFrom（To）Symbol函数时遇到问题。欢迎在块之间存储一些参数的替代方案。下面，我提供了一些（示例）代码，这些代码无法正常工作。

#include "cuda_runtime.h"
#include "device_launch_parameters.h"

#include <stdio.h>
#include <cstdlib>
#include <ctime>

int avgHost(int*, int);

cudaError_t cudaError;

__device__ int getGlobalIdx()
{
    int blockId = blockIdx.x + blockIdx.y * gridDim.x + gridDim.x * gridDim.y * blockIdx.z;
    int threadId = blockId * (blockDim.x * blockDim.y * blockDim.z) + (threadIdx.z * (blockDim.x * blockDim.y)) + (threadIdx.y * blockDim.x) + threadIdx.x;
    return threadId;
}

__device__ int avg;
__device__ int count;
__device__ int sum;

__global__ void avgKernel(const int *arr)
{
    auto idx = getGlobalIdx();
    count++;
    sum += arr[idx];
    avg = sum / count;
}


int main(int argc, char ** argv)
{
    const int arraySize = 128;
    auto arr1 = (int*)__vcrt_malloc_normal(arraySize * sizeof(int));
    srand(time(NULL));
    for (size_t i = 0; i < arraySize; i++)
    {
        arr1[i] = rand() % 100;
    }
    auto hostAvg = avgHost(arr1, arraySize);
    fprintf_s(stdout, "AVG: %d", hostAvg);
    free(arr1);
    return 0;
}

int avgHost(int* arr, int arraySize)
{
    int *dArray = nullptr;
    cudaSetDevice(0);
    cudaError = cudaMemcpyToSymbol((void *)count, (void*)0, sizeof(int), 0, cudaMemcpyHostToDevice);
    if (cudaError)
    {
        fprintf_s(stderr, "%s\t%d\n", cudaGetErrorString(cudaError), __LINE__);
        return -1;
    }
    cudaMalloc((void**)&dArray, arraySize * sizeof(int));
    cudaMemcpy(dArray, arr, arraySize * sizeof(int), cudaMemcpyKind::cudaMemcpyHostToDevice);
    avgKernel <<<1, arraySize>>> (dArray);
    cudaDeviceSynchronize();
    int hostResult = -1;
    cudaError = cudaMemcpyFromSymbol(&hostResult, (void *)avg, sizeof(int), 0, cudaMemcpyDeviceToHost);
    if (cudaError)
    {
        fprintf_s(stderr, "%s\t%d\n", cudaGetErrorString(cudaError), __LINE__);
    }
    cudaFree(dArray);
    return hostResult;
}

当我启动打印代码系统时

无效的设备符号55 AVG：-1

C：\ Users \ Administrator \ source \ repos \ CudaTests \ x64 \ Debug \ cudabase.exe（进程18152）以代码0退出。

有什么想法吗？

Answer 1

删除此行，因为启动内核之前设备变量“ count”始终为0。