  In recent years, interest in RISC-V computing architectures have moved from
academic to mainstream, especially in the field of High Performance Computing
where energy limitations are increasingly a point of concern. The results
presented in this paper are part of a longer-term evaluation of RISC-V's
viability for HPC applications. In this work, we use the Octo-Tiger
multi-physics, multi-scale, 3D adaptive mesh refinement astrophysics
application as the bases for our analysis. We report on our experience in
porting this modern C++ code (which is built upon several open-source libraries
such as HPX and Kokkos) to RISC-V. We also compare the application's
performance, scalability, and power consumption on RISC-V to an A64FX system.
