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试图在 CUDA 中运行一个程序来做矩阵乘法。我想我已经正确设置了所有内容并且程序运行并执行。问题是输出。有人看到我的代码有什么问题吗？显然，无论输入是什么，输出矩阵的值都是 0。我认为问题是我必须从使用 int Width 作为 Kernal 函数中的参数转换为使用行数/列数。我不认为/应该是一个问题，但出了点问题......感谢您的帮助！

#define TILE_WIDTH 16

// Compute C = A * B
__global__ void matrixMultiply(float * A, float * B, float * C,
               int numARows, int numAColumns,
               int numBRows, int numBColumns,
               int numCRows, int numCColumns) 
{
    //@@ Insert code to implement matrix multiplication here
    float Cvalue = 0.0;
    int Row = blockIdx.y * blockDim.y + threadIdx.y;
    int Col = blockIdx.x * blockDim.x + threadIdx.x;

    if ((Row < numCRows) && (Col < numCColumns)) 
    {       
        float Pvalue = 0;
        for (int k = 0; k < numCRows; ++k) Pvalue += A[Row*numCColumns+k] * B[k*numCRows+Col];
        C[Row*numCRows+Col] = Cvalue;
    }

}

int main(int argc, char ** argv) {
wbArg_t args;
float * hostA; // The A matrix
float * hostB; // The B matrix
float * hostC; // The output C matrix
float * deviceA;
float * deviceB;
float * deviceC;
int numARows; // number of rows in the matrix A
int numAColumns; // number of columns in the matrix A
int numBRows; // number of rows in the matrix B
int numBColumns; // number of columns in the matrix B
int numCRows; // number of rows in the matrix C (you have to set this)
int numCColumns; // number of columns in the matrix C (you have to set this)

args = wbArg_read(argc, argv);
wbTime_start(Generic, "Importing data and creating memory on host");
hostA = (float *) wbImport(wbArg_getInputFile(args, 0), &numARows, &numAColumns);
hostB = (float *) wbImport(wbArg_getInputFile(args, 1), &numBRows, &numBColumns);
//@@ Set numCRows and numCColumns
numCRows = numBRows;
numCColumns = numAColumns;  
int sizeA = numARows * numAColumns * sizeof(float);
int sizeB = numBRows * numBColumns * sizeof(float);
int sizeC = numCRows * numCColumns * sizeof(float);
//@@ Allocate the hostC matrix
hostC = (float *) malloc(sizeC);
wbTime_stop(Generic, "Importing data and creating memory on host");

wbLog(TRACE, "The dimensions of A are ", numARows, " x ", numAColumns);
wbLog(TRACE, "The dimensions of B are ", numBRows, " x ", numBColumns);

wbTime_start(GPU, "Allocating GPU memory.");
//@@ Allocate GPU memory here
cudaMalloc((void **) &deviceA, sizeA);      
cudaMalloc((void **) &deviceB, sizeB);
cudaMalloc((void **) &deviceC, sizeC);
wbTime_stop(GPU, "Allocating GPU memory.");

wbTime_start(GPU, "Copying input memory to the GPU.");
//@@ Copy memory to the GPU here
cudaMemcpy(deviceA, hostA, sizeA, cudaMemcpyHostToDevice);
cudaMemcpy(deviceB, hostB, sizeB, cudaMemcpyHostToDevice);
wbTime_stop(GPU, "Copying input memory to the GPU.");

//@@ Initialize the grid and block dimensions here
dim3 dimGrid(numCRows/TILE_WIDTH, numCColumns/TILE_sWIDTH, 1);
dim3 dimBlock(TILE_WIDTH, TILE_WIDTH, 1);

wbTime_start(Compute, "Performing CUDA computation");
//@@ Launch the GPU Kernel here
matrixMultiply<<<dimGrid,dimBlock>>>(deviceA, deviceB, deviceC,
                                        numARows, numAColumns,
                                        numBRows, numBColumns,
                                        numCRows, numCColumns);
cudaThreadSynchronize();
wbTime_stop(Compute, "Performing CUDA computation");

wbTime_start(Copy, "Copying output memory to the CPU");
//@@ Copy the GPU memory back to the CPU here      
cudaMemcpy(hostC, deviceC, sizeC, cudaMemcpyDeviceToHost);
wbTime_stop(Copy, "Copying output memory to the CPU");

wbTime_start(GPU, "Freeing GPU Memory");
//@@ Free the GPU memory here    
cudaFree(deviceA);
cudaFree(deviceB);
cudaFree(deviceC);
wbTime_stop(GPU, "Freeing GPU Memory");

wbSolution(args, hostC, numCRows, numCColumns);

free(hostA);
free(hostB);
free(hostC);

return 0;
}
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1 回答 1

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好的，所以它返回零的原因是因为我的结果从未保存到我的输出矩阵中，因为我的代码通过循环一遍又一遍地保存在一个未使用但已初始化的值中。我还搞砸了 numCRows 和 numCColumns 值，但在我的代码开始实际运行后更容易识别。

__global__ void matrixMultiply(float * A, float * B, float * C,
               int numARows, int numAColumns,
               int numBRows, int numBColumns,
               int numCRows, int numCColumns) 
{
    //@@ Insert code to implement matrix multiplication here
    int Row = blockIdx.y * blockDim.y + threadIdx.y;
    int Col = blockIdx.x * blockDim.x + threadIdx.x;

    if ((Row < numCRows) && (Col < numCColumns)) 
    {       
        float Cvalue = 0;
        for (int k = 0; k < numCRows; ++k) 
        {
          Cvalue += A[Row*numAColumns+k] * B[k*numBColumns+Col];
        }
          C[Row*numCColumns+Col] = Cvalue;
    }

}

同样在主代码中：

numCRows = numARows;
numCColumns = numBColumns;
于 2012-12-25T04:06:43.583 回答