mp2.c

// MP 2: Due Sunday, Dec 16, 2012 at 11:59 p.m. PST
#include    <wb.h>
#define TILE_SIZE 1
#define wbCheck(stmt) do {                                 \
        cudaError_t err = stmt;                            \
        if (err != cudaSuccess) {                          \
            wbLog(ERROR, "Failed to run stmt ", #stmt);    \
            return -1;                                     \
        }                                                  \
    } while(0)

// 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
    int r = blockIdx.y*blockDim.y+threadIdx.y;
    int c = blockIdx.x*blockDim.x+threadIdx.x;
    if ((r < numCRows) && (c < numCColumns)) {
        float sum = 0;
        for (int k = 0; k < numAColumns; ++k) sum += A[r*numAColumns+k] * B[k*numAColumns+c];
        C[r*numCColumns+c] = sum;
    }
}

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
    if(numAColumns != numBRows){
        wbLog(ERROR, "input matrix dimensions are invalid");
        return -1;
    }
    numCRows = numARows;
    numCColumns = numBColumns;
    //@@ Allocate the hostC matrix
    int cSize = numCRows * numCColumns * sizeof(float);
    hostC = (float *) malloc(cSize);
    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
    int aSize = numARows * numAColumns * sizeof(float);
    int bSize = numBRows * numBColumns * sizeof(float);
    wbCheck(cudaMalloc((void **) &deviceA, aSize));
    wbCheck(cudaMalloc((void **) &deviceB, bSize));
    wbCheck(cudaMalloc((void **) &deviceC, cSize));

    wbTime_stop(GPU, "Allocating GPU memory.");

    wbTime_start(GPU, "Copying input memory to the GPU.");
    //@@ Copy memory to the GPU here
    wbCheck(cudaMemcpy(deviceA, hostA, aSize, cudaMemcpyHostToDevice));
    wbCheck(cudaMemcpy(deviceB, hostB, bSize, cudaMemcpyHostToDevice));

    wbTime_stop(GPU, "Copying input memory to the GPU.");
    
    //@@ Initialize the grid and block dimensions here
    dim3 dimGrid(ceil(numCColumns/TILE_SIZE), ceil(numCRows/TILE_SIZE), 1);
    dim3 dimBlock(TILE_SIZE, TILE_SIZE, 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, cSize, cudaMemcpyDeviceToHost);

    wbTime_stop(Copy, "Copying output memory to the CPU");

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

    wbTime_stop(GPU, "Freeing GPU Memory");

    wbSolution(args, hostC, numCRows, numCColumns);

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

    return 0;
}