Question

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

#define SZ_INT sizeof(int)
#define CELL_SZ 1
#define CELL_VALUE(a,x) (((a) << 1) | x)
#define FROM(a) ((a) & 1)
#define LENGTH(a) ((a) >> 1)
#define INDEX(i,j,m) ((i) * (m + 1) + j)
//FROM: 1 if L[i][j] took value from L[i - 1][j], 0 if L[i][j] took value from L[i][j - 1]

#define CUDA_CHECK_ERROR(err)           \
if (err != cudaSuccess) {          \
printf("Cuda error: %s\n", cudaGetErrorString(err));    \
printf("Error in file: %s, line: %i\n", __FILE__, __LINE__);  \
}  

__global__ void Find_L_entry (int *L, int *A, int n, int *B, int m, int diag) {
        int j = threadIdx.x + blockIdx.x * blockDim.x;
        int i = diag - j;
        if (i >= 0 && i < n && j >= 0 && j < m) {
                if (A[i] == B[j]) {
                        L[INDEX(i, j, m)] = CELL_VALUE(LENGTH(L[INDEX(i - 1, j - 1,     m)]) + 1, 0);
                } else {
                    L[INDEX(i, j, m)] = (LENGTH(L[INDEX(i - 1, j, m)]) >     LENGTH(L[INDEX(i, j - 1, m)])) ?
                                CELL_VALUE(LENGTH(L[INDEX(i - 1, j, m)]), 1) :
                               CELL_VALUE(LENGTH(L[INDEX(i, j - 1, m)]), 0);
                }
        }
}

__host__ void output_sequence(int *L, int *A, int n, int *B, int m) {
        int len = LENGTH(L[INDEX(n - 1, m - 1, m)]);
        int i = n - 1, j = m - 1;
        int *lcs = (int*) malloc(len * SZ_INT);
        int top = 0;
        while (i >= 0 && j >= 0) {
                if (A[i] == B[j]) {
                        lcs[top++] = A[i];
                        i--; j--;
                } else {
                        if (FROM(L[INDEX(i, j, m)]) == 1)
                                i--;
                        else
                                j--;
                }
        }
        printf("Length: %d\nSequence: ", len);
        for (int i = len - 1; i >= 0; i--) {
                printf("%d%c", lcs[i], i ? ' ' : '\n');
        }
        free(lcs);
}

__host__ void read_sequence(int *&A, int &n, int num) {
        printf("Enter number of elements in sequence %d\n", num);
        scanf("%d", &n);
        A = (int*) malloc(n * sizeof(int));
        printf("Enter %d elements of sequence %d\n", n, num);
        for (int i = 0; i < n; i++)
                scanf("%d", A + i);
}

int main ( int argc, char **argv ) {
        int number_of_blocks = atoi(argv[1]), threads_in_block = atoi(argv[2]);
        int n, m;
        int *A, *B;
        read_sequence(A, n, 1);
        read_sequence(B, m, 2);

    int *d_A, *d_B;
    cudaMalloc((void**)&d_A, n * SZ_INT);
    cudaMalloc((void**)&d_B, m * SZ_INT);

    CUDA_CHECK_ERROR(cudaMemcpy(d_A, A, n * SZ_INT, cudaMemcpyHostToDevice));
    CUDA_CHECK_ERROR(cudaMemcpy(d_B, B, m * SZ_INT, cudaMemcpyHostToDevice));

    int *big_L = (int*) malloc((n + 1) * (m + 1) * CELL_SZ * SZ_INT);
    for (int i = 0; i < (n + 1) * (m + 1) * CELL_SZ; i++)
            big_L[i] = 0;

    int *L = &big_L[(m + 2) * CELL_SZ];
    int *dev_L;
    cudaMalloc((void**)&dev_L, (n + 1) * (m + 1) * SZ_INT);
    int *d_L = &dev_L[(m + 2) * CELL_SZ];
    CUDA_CHECK_ERROR(cudaMemcpy(d_L, L, (n * (m + 1) - 1) * SZ_INT, cudaMemcpyHostToDevice));

    int diag_count = n + m - 1;

    for (int diag = 0; diag < diag_count; diag++) {
            CUDA_CHECK_ERROR(cudaMemcpy(d_L, L, SZ_INT, cudaMemcpyHostToDevice));
            Find_L_entry<<<number_of_blocks, threads_in_block>>>(d_L, d_A, n, d_B, m, diag);
            CUDA_CHECK_ERROR(cudaPeekAtLastError());
            CUDA_CHECK_ERROR(cudaMemcpy(L, d_L, (n * (m + 1) - 1) * CELL_SZ * SZ_INT, cudaMemcpyDeviceToHost));
            CUDA_CHECK_ERROR(cudaDeviceSynchronize());
            for (int i = 0; i < n; i++)
                    for (int j = 0; j < m; j++)
                            printf("%d%c", L[INDEX(i,j,m)], j == m - 1 ? '\n' : ' ');
            system("pause");
            CUDA_CHECK_ERROR(cudaThreadSynchronize());
    }
    CUDA_CHECK_ERROR(cudaMemcpy(L, d_L, (n * (m + 1) - 1) * CELL_SZ * SZ_INT, cudaMemcpyDeviceToHost));

    output_sequence(L, A, n, B, m);

    cudaFree(d_L);
    cudaFree(d_A);
    cudaFree(d_B);


    free(A); free(B); free(big_L);

    return 0;
}

代码无法正常运行。在调用函数Find_L_entry后，aray d_L不会改变。
我正在通过cmd进行编译。

nvcc -g -G -arch=sm_21 -o lcs.exe lcs.cu
当我运行它时，我收到运行时错误：“Cuda错误：功能中的设备无效，第94行”

Answer 1

您收到的运行时错误正在发生，因为运行时API无法找到或创建可在GPU上运行的代码。

根本原因是您正在编译与GPU不兼容的体系结构（计算能力2.1）的代码。你已经声明你有一个GT310M，你可以从here看到它是一个计算能力1.2设备。 CUDA工具链支持向后代码兼容性（即旧代码将在新设备上运行），但不是相反。

你应该像这样构建你的代码：

nvcc -g -G -arch=sm_12 -o lcs.exe lcs.cu

CUDA功能不会更改数据

1 个答案: