  3D detailed radiative transfer is computationally taxing, since the solution
of the radiative transfer equation involves traversing the six dimensional
phase space of the 3D domain. With modern supercomputers the hardware available
for wallclock speedup is rapidly changing, mostly in response to requirements
to minimize the cost of electrical power. Given the variety of modern computing
architectures, we aim to develop and adapt algorithms for different computing
architectures to improve performance on a wide variety of platforms. We
implemented the main time consuming kernels for solving 3D radiative transfer
problems for vastly different computing architectures using MPI, OpenMP,
OpenACC and vector algorithms. Adapted algorithms lead to massively improved
speed for all architectures, making extremely large model calculations easily
feasible. These calculations would have previously been considered impossible
or prohibitively expensive. Efficient use of modern computing devices is
entirely feasible, but unfortunately requires the implementation of specialized
algorithms for them.
