Intel® Distribution of OpenVX* Implementation Developer Guide

  • 04/03/2020
  • Public Content
Contents

Optional Callbacks for Kernels Supporting Advanced Tiling

An advanced tiling kernel can optionally provide the following callback functions, which if set, are called by the OpenVX* runtime within
vxVerifyGraph
 or
vxProcessGraph
:
  • Initialize 
    
typedef vx_status (*vx_kernel_initialize_f)(vx_node node, const vx_reference 
 *parameters, vx_uint32 num);
    If set, called once during
    vxVerifyGraph
     after all input and output parameters have been verified.
  • De-Initialize
    
typedef vx_status (*vx_kernel_deinitialize_f)(vx_node node, const vx_reference 
 *parameters, vx_uint32 num);
    If set, this function is called during node destruction.
    The two functions above are regular callbacks required for any user kernel as defined by the OpenVX* 1.0.1/1.1 specifications. Refer to the standard specification from Khronos* for more details on usage and the Putting it all Together: Example Code section for a code example.
  • Pre-Process
    
typedef vx_status (*vx_kernel_preprocess_intel_f)(vx_node node, const 
 vx_reference *parameters, vx_uint32 num, void * tile_memory[], vx_uint32 
 num_tile_memory_elements,vx_size tile_memory_size);
    If set, this function is called once at the beginning of each user call to
    vxProcessGraph
    , before any nodes in the graph have started processing. It is intended to be used to perform any required per-vxProcessGraph initialization, which may be required for certain kernels.
  • Post-Process
    
typedef vx_status (*vx_kernel_postprocess_intel_f)(vx_node node, const 
 vx_reference *parameters, vx_uint32 num, void * tile_memory[], vx_uint32 
 num_tile_memory_elements,vx_size tile_memory_size);
    If set, this function is called once at the end of each user call to
    vxProcessGraph
    , after all nodes in the graph have completed processing. It is intended to be used to perform any required per-vxProcessGraph de-initialization or data aggregation that may be required for certain kernels.
    NOTE: As this function is called after all nodes in the graph have completed processing, it is not a good idea to set values of output parameters in this function, if the parameter is further used as an input parameter to another node in the same graph.
  • Set Tile Dimensions
    
typedef vx_status (*vx_kernel_set_tile_dimensions_intel_f)(vx_node node, 
 const vx_reference *parameters, vx_uint32 param_num, const vx_tile_block_size_intel_t 
 *current_tile_dimensions, vx_tile_block_size_intel_t *updated_tile_dimensions);
    If set, this function is called within
    vxVerifyGraph
     to give a kernel the ability to override the current output tile size chosen by the runtime with a custom tile size. For example, a kernel may be designed to work only with tile widths that equal the output image size. The function is required to set the updated tile dimensions using a combination of the kernel parameters and current tile dimensions, which is passed in as an input parameter.
  • Initialize (as a function of tile dimensions)
    
typedef vx_status (*vx_kernel_tile_dimensions_initialize_intel_f)(vx_node 
 node, const vx_reference *parameters, vx_uint32 param_num, const vx_tile_block_size_intel_t 
 *current_tile_dimensions);
    If set, this function is called within
    vxVerifyGraph
     to give a kernel the ability to perform some initialization as a function of the currently set tile dimensions. For example, a kernel may want to set some node attribute, such as
    VX_KERNEL_TILE_MEMORY_SIZE_INTEL
    , as a function of the currently set tile dimensions.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.