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Thread: help with globalWorkSize

  1. #1

    help with globalWorkSize

    please can you help me with this? There must be something what I'm overseeing.

    I'm passing to kernel 2 buffers, each with 4 values. One contains data and another one should return data from kernel. So when I run my kernel and pass 4 as a global_work_size it should work. But instead of that in my return buffer I get only 2 values. Everything works if I double the size of global_work_size to 8,...why?

    Here is the code (very simplified):
    kernel:
    Code :
    __kernel void mainGard(__global const double *Bij,
                           __global double *result)
    {
        int gid = get_global_id(0);
        result[gid] = Bij[gid];
    }

    host:
    Code :
    cl_uint nTotalBij = 4
    cl_double *Bij = new cl_double[nTotalBij];
    for(int i=0; i<4;i++)
         Bij[i] = i;
    cl_double result[nTotalBij];
     
    memObjects[0] = clCreateBuffer(context, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR,
                                     sizeof(cl_double) * nTotalBij, Bij, NULL);
    memObjects[1] = clCreateBuffer(context, CL_MEM_READ_WRITE,
                                     sizeof(cl_double) * nTotalBij, NULL, NULL);
     
    errCode = clSetKernelArg(kernel, 0, sizeof(cl_mem), &memObjects[0]);
    errCode = clSetKernelArg(kernel, 1, sizeof(cl_mem), &memObjects[1]);
    size_t globalWorkSize[1] = { 4 }; 
    size_t localWorkSize[1] = { 1 };
     
    // Queue the kernel up for execution across the array
    errCode = clEnqueueNDRangeKernel(commandQueue, kernel, 1, NULL,
                                             globalWorkSize, localWorkSize,
                                             0, NULL, &event)

  2. #2

    Re: help with globalWorkSize

    ok, so everything is OK with my code. Problem is that double precision is not supported on my pc. Changing to float will solve the issue.

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