swKokkos: An Athread Backend for Enhanced Kokkos with the Sunway Heterogeneous Architecture

Performance portability is crucial for enabling the efficient execution of high-performance applications across evolving heterogeneous architectures. The Kokkos library offers an abstraction layer that decouples algorithmic logic from hardware-specific details. However, Kokkos lacks support for the Sunway processor, which is an essential heterogeneous architecture. We present swKokkos, an Athread backend that enables Kokkos on the Sunway many-core architecture. It introduces a compile-time kernel registration and runtime callback mechanism that breaks prior barriers preventing the template-intensive C++ Kokkos library from executing on Sunway compute processing elements (CPEs). We further implement three targeted optimizations: (1) vectorized hash-based callback dispatch to cut runtime abstraction overhead, (2) tile-based parallel task mapping algorithm to improve flexibility and load distribution, and (3) a fast device scheduling library that reduces device-side scheduling latency. We evaluate swKokkos for performance across multiscale scenarios. Moreover, swKokkos achieves up to 34.0× speedup over the host backend. Compared to the native device backend solution, it ranges from 0.7× to 2.8×, indicating that the abstraction overhead is low and occasionally reversed into gains through improved scheduling. In particular, swKokkos scales efficiently and stably to over 100000 core simulations in a real-world application, demonstrating its ability to support extreme-scale simulations on the Sunway exascale supercomputer.