Function max_potential_block_size 

pub fn max_potential_block_size(
    func: &Function,
    dynamic_smem_bytes: usize,
    block_size_limit: i32,
) -> Result<(i32, i32)>

Block size that maximises occupancy for func, assuming the given fixed dynamic_smem_bytes. Returns (min_grid_size, optimal_block_size): launch min_grid_size blocks of optimal_block_size threads to cover the device with peak SM-utilization.

block_size_limit clamps the returned block size; pass 0 for the device’s documented maximum.