How to return a value from Cudafy c# GPU calculation?

Question

My Issue

Hey, so I'm making this simple calculation to find the sum of sins between 0 and 100 degrees(as I use it as a benchmark for my systems), the calculation isn't the problem my issue is that I am new to Cudafy and I am unsure on how to properly pass in and return values so that it can be printed off here is my code:

Code

    public const int N = 33 * 1024;
    public const int threadsPerBlock = 256;
    public const int blocksPerGrid = 32;                                           

    public static void Main()
    {
        Stopwatch watch = new Stopwatch();                                          
        watch.Start();                                                              
        string Text = "";
        int iterations = 1000000;
        CudafyModule km = CudafyTranslator.Cudafy();
        GPGPU gpu = CudafyHost.GetDevice(CudafyModes.Target, CudafyModes.DeviceId);
        gpu.LoadModule(km);
        double[] dev_Value = gpu.Allocate<double>();
        gpu.Launch(blocksPerGrid, threadsPerBlock).SumOfSines(iterations,dev_Value);                                                     

        double Value;
        gpu.CopyFromDevice(dev_Value, out Value);
        watch.Stop();                                                                                                
        Text = watch.Elapsed.TotalSeconds.ToString();                                                                
        Console.WriteLine("The process took a total of: " + Text + " Seconds");
        Console.WriteLine(Value);
        Console.Read();
        gpu.FreeAll();
    }
    [Cudafy]
    public static void SumOfSines(GThread thread,int iterations,double [] Value)
    {
        double total = new double();
        double degAsRad = Math.PI / 180.0;
        for (int i = 0; i < iterations; i++)
        {
            total = 0.0;
            for (int z = 1; z < 101; z++)
            {
                double angle = (double)z * degAsRad;
                total += Math.Sin(angle);
            }

        }
        Value[0] = total;


    }

The value that I am trying to extract from the CUDAfy part is the total and then print it off aswell as printing the time for the benchmarking. If anyone could post advice it would be very much appreciated (also any suggestions for making rid of any useless lines or unefficient pieces would also be good).

And isn't it in `dev_Value[0]`? – Andrew Oct 14 '16 at 06:24 — Andrew, Oct 14 '16 at 06:24

score 4 · Accepted Answer · answered Oct 19 '16 at 10:50

Doesn't matter I found the answer but I'll post it here:

    public const int N = 33 * 1024;
    public const int threadsPerBlock = 256;
    public const int blocksPerGrid = 32;

    public static void Main()
    {
        Stopwatch watch = new Stopwatch();
        watch.Start();
        CudafyModule km = CudafyTranslator.Cudafy();

        GPGPU gpu = CudafyHost.GetDevice(CudafyModes.Target, CudafyModes.DeviceId);
        gpu.LoadModule(km);

        string Text = "";
        int iterations = 1000000;
        double Value;
        double[] dev_Value = gpu.Allocate<double>(iterations * sizeof(double));
        gpu.Launch(blocksPerGrid, threadsPerBlock).SumOfSines(iterations, dev_Value);
        gpu.CopyFromDevice(dev_Value, out Value);
        watch.Stop();
        Text = watch.Elapsed.TotalSeconds.ToString();
        Console.WriteLine("The process took a total of: " + Text + " Seconds");
        Console.WriteLine(Value);
        Console.Read();
        gpu.FreeAll();
    }

    [Cudafy]
    public static void SumOfSines(GThread thread, int _iterations, double[] Value)
    {
        int threadID = thread.threadIdx.x + thread.blockIdx.x * thread.blockDim.x;
        int numThreads = thread.blockDim.x * thread.gridDim.x;
        if (threadID < _iterations){
            for (int i = threadID; i < _iterations; i += numThreads)
            {
                double _degAsRad = Math.PI / 180;
                Value[i] = 0.0;
                for (int a = 0; a < 100; a++)
                {
                    double angle = (double)a * _degAsRad;
                    Value[i] += Math.Sin(angle);
                }
            }
        }
    }

-Jack

How to return a value from Cudafy c# GPU calculation?

1 Answers1