Hi,
On 05/23/2016 05:38 PM, Charles Determan wrote:
> I am experimenting with the custom OpenCL kernel functionality,
> specifically a naive matrix multiplication as an example.
>
> My OpenCL Kernel:
> __kernel void iMatMult(const int Mdim, const int Pdim,
> __global const int *A, __global const int *B,
> __global int *C) {
>
> // Get the index of the elements to be processed
> const int globalRow = get_global_id(0); // C Row ID
> const int globalCol = get_global_id(1); // C Col ID
> int tmp = 0;
>
> // Do the operation
> for(int k=0; k < Pdim; k++){
> tmp += A[k*Mdim+globalRow] * B[globalCol*Pdim+k];
> }
> C[globalCol*Mdim+globalRow] = tmp;
> }
>
>
> Relevant C++ code
> where vcl_* refer to viennacl::matrix<int>
> and my_kernel is a string referring to the kernel above:
>
> int M = vcl_A.size2();
> int P = vcl_A.size1();
>
> // add kernel to program
> viennacl::ocl::program & my_prog =
> viennacl::ocl::current_context().add_program(my_kernel, "my_kernel");
>
> // get compiled kernel function
> viennacl::ocl::kernel & my_kernel_mul = my_prog.get_kernel("iMatMult");
>
> // execute kernel
> viennacl::ocl::enqueue(my_kernel_mul(M, P, vcl_A, vcl_B, vcl_C));
>
>
> Oddly, the results in the vcl_C object are incorrect. But if I manually
> go through the OpenCL using the C++ API the results are correct (which
> you can see the API code here
> https://github.com/cdeterman/gpuR/blob/develop/src/gpuMatrix_igemm.cpp). Did
> I miss something?
yes, you missed the internal data layout: rows/columns may be padded
with zeros:
http://viennacl.sourceforge.net/doc/manual-types.html#manual-types-matrix
(this has performance reasons, but it is - unfortunately - often
overlooked by users)
Best regards,
Karli
>
>
>
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Mobile security can be enabling, not merely restricting. Employees who
bring their own devices (BYOD) to work are irked by the imposition of MDM
restrictions. Mobile Device Manager Plus allows you to control only the
apps on BYO-devices by containerizing them, leaving personal data untouched!
https://ad.doubleclick.net/ddm/clk/304595813;131938128;j
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