Scientific modeling and simulation software is ubiquitous at Sandia National Laboratories and is integral to providing empirical justification to critical mission decisions. Models are increasingly being expressed as workflows to simplify the many steps needed in scientific analyses but keeping these models and workflows alive for the decades-long timescales needed by Sandia remains a struggle. Additionally, the manual use and (lack of) maintenance of these models creates significant risks for duplicated work and model capability loss over time from changing personnel and computing environments. To address these issues, we are building the Engineering Common Modeling Framework (ECMF), a platform for scientific model sustainment at Sandia. ECMF enables the automatic evaluation of models over time and will ensure that models created at Sandia are discoverable and ready to be revisited, extended, and reused. In this paper, we report our current and planned capabilities as well as lessons learned from our framework development process.

To keep pace with the demand for innovation through scientific computing, modern scientific software development is increasingly reliant upon a rich and diverse ecosystem of software libraries and toolchains. Research software engineers (RSEs) responsible for that infrastructure perform highly integrative work, acting as a bridge between the hardware, the needs of researchers, and the software layers situated between them; relatively little, however, has been written about the role played by RSEs in that work and what support they need to thrive. To that end, we present a two-part report on the development of half-precision floating point support in the Kokkos Ecosystem. Half-precision computation is a promising strategy for increasing performance in numerical computing and is particularly attractive for emerging application areas (e.g., machine learning), but developing practicable, portable, and user-friendly abstractions is a nontrivial task. In the first half of the paper, we conduct an engineering study on the technical implementation of the Kokkos half-precision scalar feature and showcase experimental results; in the second half, we offer an experience report on the challenges and lessons learned during feature development by the first author. We hope our study provides a holistic view on scientific library development and surfaces opportunities for future studies into effective strategies for RSEs engaged in such work.

As the push towards exascale hardware has increased the diversity of system architectures, performance portability has become a critical aspect for scientific software. We describe the Kokkos Performance Portable Programming Model that allows developers to write single source applications for diverse high-performance computing architectures. Kokkos provides key abstractions for both the compute and memory hierarchy of modern hardware. We describe the novel abstractions that have been added to Kokkos version 3 such as hierarchical parallelism, containers, task graphs, and arbitrary-sized atomic operations to prepare for exascale era architectures. We demonstrate the performance of these new features with reproducible benchmarks on CPUs and GPUs.