PyOP2: A High-Level Framework for Performance-Portable Simulations on Unstructured Meshes

Emerging many-core platforms are very difficult to program in a performance portable manner whilst achieving high efficiency on a diverse range of architectures. We present work in progress on PyOP2, a high-level embedded domain-specific language for mesh-based simulation codes that executes numerical kernels in parallel over unstructured meshes. Just-in-time kernel compilation and parallel scheduling are delayed until runtime, when problem-specific parameters are available. Using generative metaprogramming, performance portability is achieved, while details of the parallel implementation are abstracted from the programmer. PyOP2 kernels for finite element computations can be generated automatically from equations given in the domain-specific Unified Form Language. Interfacing to the multi-phase CFD code Fluidity through a very thin layer on top of PyOP2 yields a general purpose finite element solver with an input notation very close to mathematical formulae. Preliminary performance figures show speedups of up to 3.4× compared to Fluidity´s built-in solvers when running in parallel.