Grid Block launch configuration

Accelerated Computing CUDA CUDA Programming and Performance
#1

Hi,

I would like to ask if there are anyone who knows if the configuration of the grid and block would affect the performance of a CUDA program?

My program works based on each thread to each pixels. To simplify things, I make my block size to be 1D. (i.e. dim3 block(1,N)). However, when trying to optimize, I tried to make it 2D (i.e. dim3 block(M,M) where M is multiple of 16) and it turns out it runs faster.

It really puzzles me, how the configuration improves the performance. Does it have to do with the architecture? Anyone? :turned: Thanks!

#2

Maybe it is just your code. Could you share the kernel as well?

#3

Without the code (at least how do you access data and what do you do with it) we can only give you some hints.

    [*]Block size can affect the occupancy (number of simultaneous blocks per multiprocessor).[*]You read data from a texture, which data is cached and prefetched in a 2D neighbors fashion)

Those are the main aspects that come to my head.

Regards,

Pablo.