从 cuda 设备上的统一内存打印数组不起作用

Question

我尝试在 cuda 设备上创建一些散列并在主机上打印它们。但是在主机的 printf 中，我在位置 0x000000000100002F

处收到读取错误

相关行如下所示：

int main() {
const int block_size = 2;
const int num_blocks = 256;
const int N = block_size * num_blocks;

unsigned char** hashes;

cudaMallocManaged(&hashes, N * (32 * sizeof(unsigned char)));
cudaMemset(hashes, 0, N * (32 * sizeof(unsigned char)));

在设备上

__global__ void sha256_kernel(unsigned char **dhashes){

    int idx = blockIdx.x * blockDim.x + threadIdx.x;


    sha256_final(&ctx, sha);
    dhashes[idx] = sha;
        //  printf("%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x\n", dhashes[idx][0], dhashes[idx][1], dhashes[idx][2], dhashes[idx][3], dhashes[idx][4], dhashes[idx][5], dhashes[idx][6], dhashes[idx][7], dhashes[idx][8], dhashes[idx][9], dhashes[idx][10], dhashes[idx][11], dhashes[idx][12], dhashes[idx][13], dhashes[idx][14], dhashes[idx][15],
        //      dhashes[idx][16], dhashes[idx][17], dhashes[idx][18], dhashes[idx][19], dhashes[idx][20], dhashes[idx][21], dhashes[idx][22], dhashes[idx][23], dhashes[idx][24], dhashes[idx][25], dhashes[idx][26], dhashes[idx][27], dhashes[idx][28], dhashes[idx][29], dhashes[idx][30], dhashes[idx][31]);
        // printing here is correct
    }

然后回到主机端...

sha256_kernel << < num_blocks, block_size>> > (hashes);
        cudaDeviceSynchronize();
        
        for (int i = 0; i < N; i++) {
            printf("%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x\n", hashes[i][0], hashes[i][1], hashes[i][2], hashes[i][3], hashes[i][4], hashes[i][5], hashes[i][6], hashes[i][7], hashes[i][8], hashes[i][9], hashes[i][10], hashes[i][11], hashes[i][12], hashes[i][13], hashes[i][14], hashes[i][15],
                hashes[i][16], hashes[i][17], hashes[i][18], hashes[i][19], hashes[i][20], hashes[i][21], hashes[i][22], hashes[i][23], hashes[i][24], hashes[i][25], hashes[i][26], hashes[i][27], hashes[i][28], hashes[i][29], hashes[i][30], hashes[i][31]);
    }//printing here doesn't work

似乎是正确的，但是当我尝试在主机上打印哈希值时，出现读取错误？

Answer 1

您用来保存哈希值的内存分配不正确。要为每个散列有一个指向内存的指针数组，您需要为指针数组和散列本身分配内存，例如：

unsigned char** hashes;
unsigned char* buff;

cudaMallocManaged(&hashes, N * sizeof(unsigned char*));
cudaMallocManaged(&buff, N * (32 * sizeof(unsigned char)));
cudaMemset(buff, 0, N * (32 * sizeof(unsigned char)));

for(i=0; i<N; i++) hashes[i] = &buff[i*32];

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从 cuda 设备上的统一内存打印数组不起作用

printing array from unified memory on cuda device doesn`t work

c++

arrays

cuda

unified-memory