This report documents the completion of milestone STPRO4-4 Kokkos back-ends research, collaborations, development, optimization, and documentation. The Kokkos team updated its existing backend to support the software stack and hardware of DOE's Sierra, Summit and Astra machines. They also collaborated with ECP PathForward vendors on developing backends for possible exa-scale architectures. Furthermore, the team ramped up its engagement with the ISO/C++ committee to accelerate the adoption of features important for the HPC community into the C++ standard.
In order to develop a healthy community around the Kokkos programming model it is necessary to put a support infrastructure in place. That infrastructure must serve the users needs in finding information about Kokkos, get connected to experts to answer questions about how to use Kokkos as well as provide mechanisms to report bugs and request new capabilities. One key aspect of such an infrastructure is that it should be scalable, i.e. that the approach works in the early stages with just a few users as well as in later stages, where Kokkos may have thousands of active users.