  In this paper, we report the implementation and measured performance of our
extreme-scale global simulation code on Sunway TaihuLight and two PEZY-SC2
systems: Shoubu System B and Gyoukou. The numerical algorithm is the parallel
Barnes-Hut tree algorithm, which has been used in many large-scale
astrophysical particle-based simulations. Our implementation is based on our
FDPS framework. However, the extremely large numbers of cores of the systems
used (10M on TaihuLight and 16M on Gyoukou) and their relatively poor memory
and network bandwidth pose new challenges. We describe the new algorithms
introduced to achieve high efficiency on machines with low memory bandwidth.
The measured performance is 47.9, 10.6 PF, and 1.01PF on TaihuLight, Gyoukou
and Shoubu System B (efficiency 40\%, 23.5\% and 35.5\%). The current code is
developed for the simulation of planetary rings, but most of the new algorithms
are useful for other simulations, and are now available in the FDPS framework.
