Coursera MP1

blablabla


// MP 1
#include    <wb.h>

__global__ void vecAdd(float * in1, float * in2, float * out, int len) {
    //@@ Insert code to implement vector addition here
    int i = threadIdx.x + blockDim.x * blockIdx.x;
	if(i < len) {
    	out[i] = in1[i] + in2[i];
  	}
}

int main(int argc, char ** argv) {
    wbArg_t args;
    int inputLength;
    float * hostInput1;
    float * hostInput2;
    float * hostOutput;
    float * deviceInput1;
    float * deviceInput2;
    float * deviceOutput;

    args = wbArg_read(argc, argv);

    wbTime_start(Generic, "Importing data and creating memory on host");
    hostInput1 = (float *) wbImport(wbArg_getInputFile(args, 0), &inputLength);
    hostInput2 = (float *) wbImport(wbArg_getInputFile(args, 1), &inputLength);
    hostOutput = (float *) malloc(inputLength * sizeof(float));
    wbTime_stop(Generic, "Importing data and creating memory on host");

    wbLog(TRACE, "The input length is ", inputLength);

    wbTime_start(GPU, "Allocating GPU memory.");
    //@@ Allocate GPU memory here
    cudaMalloc((void**)&deviceInput1,inputLength*sizeof(float));
    cudaMalloc((void**)&deviceInput2,inputLength*sizeof(float));
    cudaMalloc((void**)&deviceOutput,inputLength*sizeof(float));

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

    wbTime_start(GPU, "Copying input memory to the GPU.");
    //@@ Copy memory to the GPU here
    cudaMemcpy(deviceInput1,hostInput1,inputLength*sizeof(float),cudaMemcpyHostToDevice);
    cudaMemcpy(deviceInput2,hostInput2,inputLength*sizeof(float),cudaMemcpyHostToDevice);

    wbTime_stop(GPU, "Copying input memory to the GPU.");

    //@@ Initialize the grid and block dimensions here
    dim3 DimGrid((inputLength*sizeof(float) -1)/256 +1 , 1 , 1);
    dim3 DimBlock(256 , 1, 1);  


    wbTime_start(Compute, "Performing CUDA computation");
    //@@ Launch the GPU Kernel here
    vecAdd<<<DimGrid,DimBlock>>>(deviceInput1,deviceInput2,deviceOutput,inputLength);
    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(hostOutput,deviceOutput,inputLength*sizeof(float),cudaMemcpyDeviceToHost);
    wbTime_stop(Copy, "Copying output memory to the CPU");

    wbTime_start(GPU, "Freeing GPU Memory");
    //@@ Free the GPU memory here
    cudaFree(deviceInput1);
    cudaFree(deviceInput2);
    cudaFree(deviceOutput);

    wbTime_stop(GPU, "Freeing GPU Memory");

    wbSolution(args, hostOutput, inputLength);

    free(hostInput1);
    free(hostInput2);
    free(hostOutput);

    return 0;
}

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