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Linux/AM5728: OpenCV optimization

Jian Zhou
Intellectual 1930 points
Part Number: AM5728

Tool/software: Linux

Hi expert ,

My customer now optimizing the OpenCV function of ocl_goodFeaturesToTrack() using the method of http://processors.wiki.ti.com/index.php/OpenCV#OpenCL_kernel_dispatch_from_OpenCV_application.2C_using_standard_OpenCL_dispatch_with_access_to_OpenCV_data_objects

They find that there are differece in args between ocl_goodFeaturesToTrack() and the functions in gftt.cl.

In ocl_goodFeaturesToTrack(), the args of maxEigenVal is

k.args(eigarg, eig.cols, (int)eig.total(), dbarg);

but in maxEigenVal() in gftt.cl, the arg is

(__global const uchar * srcptr, int src_step, int src_offset, int cols,int total, __global uchar * dstptr)

So what is the relationship of eigarg and global const uchar * srcptr, int src_step, int src_offset,

Thanks!

  • 0
    TI__Guru**** 393215 points
    The software team have been notified. They will respond here.
  • 0 in reply to Biser Gatchev-XID
    Prodigy 30 points
    Thanks! and the ocl_goodFeaturesToTrack() function is in OpenCV/modules/imgproc/src/featureselect.cpp.
  • 0 in reply to user5000237
    TI__Genius 9065 points
    This is a OpenCV baseline code (nothing related to TI modifications). Here is code snippet from featureselect.cpp:
    …
    ocl::KernelArg eigarg = ocl::KernelArg::ReadOnlyNoSize(eig),
    dbarg = ocl::KernelArg::PtrWriteOnly(maxEigenValue),
    maskarg = ocl::KernelArg::ReadOnlyNoSize(mask),
    cornersarg = ocl::KernelArg::PtrWriteOnly(corners_buffer);

    if (haveMask)
    k.args(eigarg, eig.cols, (int)eig.total(), dbarg, maskarg);
    else
    k.args(eigarg, eig.cols, (int)eig.total(), dbarg);

    size_t globalsize = dbsize * wgs;
    if (!k.run(1, &globalsize, &wgs, false))
    return false;
    …
    OpenCV provides class KernelArg, in file ./modules/core/includes/opencv2/core/ocl.hpp
    There they can see that more than one argument is returned (w/ default values set, for extra two arguments if not explicitly set in above call).
    E.g.
    static KernelArg ReadOnlyNoSize(const UMat& m, int wscale=1, int iwscale=1)
    { return KernelArg(READ_ONLY+NO_SIZE, (UMat*)&m, wscale, iwscale); }
  • 0 in reply to dzhou
    TI__Intellectual 1930 points

    David,

    Thanks for your support!

  • 0 in reply to Jian Zhou
    TI__Intellectual 1930 points

    Hi David,

    Customer recently ask a question that as OpenCV use data structure "UMat" and OpenCL use data structure "Buffer" for date transfer, since customer use OptionB, is there any function() can transfer "UMat" to "Buffer" that similar with the function of :

    void cv::ocl::convertFromBuffer  ( void *  cl_mem_buffer,  size_t  step,  int  rows,  int  cols,  int  type,  UMat &  dst )   

    Thanks!

  • 0 in reply to Jian Zhou
    TI__Intellectual 1930 points
    Hi David,
    During the OpenCV-OpenCL optimization, there is many data transfer between MAT structure in OpenCV and UMAT structure in OpenCL, customer find this data transfer will lead to high CPU occupy that influnce on other operation, as UMAT and MAT are all in DDR, do we have any method to optimaze this data transfer?