.CU syntax "<<< >>>"


I am new in CUDA and trying to understand the boxfilter example in SDK. Can anyone help me with the following line of codes:

d_boxfilter_rgba_x<<< height / nthreads, nthreads, 0 >>>( d_temp, width, height, radius);

what is <<< height / nthreads, nthreads, 0 >>> doing there? Is it a template setting up the block and thread?


<<<gridDimensions, blockDimensions>>> is the extremely unfortunate syntax used by CUDA to invoke a kernel using the Runtime API, specifying the grid and block dimensions respectively… just another reason to avoid the Runtime API, heh.

This is mentioned in the CUDA Programming Guide, section 2.x (2.1 and 2.2 specifically).