Decide on the minimum chunk of work for OpenMP

Created by: aprokop

Right now, strong scaling of OpenMP run will start increasing the OpenMP time for smaller problems, once the ratio of objects/thread hits certain threshold. We need to figure out the minimal amount of work per thread so that they won't be penalized.

Summit 21 threads/smt1 construction filled box summit_construction_filled_box_21_smt_1

Summit 168 threads/smt4 construction filled box summit_construction_filled_box_168_smt_4