Building Julia proxy mini apps for HPC system evaluation

We will showcase our efforts building Julia proxy applications, or mini apps, targeting the Summit and Frontier supercomputers. We developed XSBench.jl to simulate on-node CPU and GPU scalability of a Monte Carlo computational kernel and, and RIOPA.jl for parallel input/output (I/O) strategies. We will share the lessons learned from Julia’s fresh approach for performance and productivity as a viable language, similar to Fortran, C and C++ for high-performance computing (HPC) systems.

We are developing Julia proxy applications, also known as mini apps, to understand the effects of parallel computation, memory, network and input/output (I/O) on the latest U.S. Department of Energy (DOE) extremely heterogeneous high-performance computing (HPC) systems. Our initial targets are the systems hosted at the Oak Ridge Leadership Computing Facility (OLCF): the Summit supercomputer, powered by IBM CPUs and NVIDIA GPUs; and the upcoming Frontier exascale system, powered by AMD CPUs and GPUs. Proxy applications, or mini apps, are simple yet powerful programs that isolate the important computational aspects that drive fully featured science applications. In this lighting talk, our efforts in developing two open-source proxy applications are presented: i) XSBench.jl, which is a port of the original C-based XSBench proxy app used to simulate on-node scalability of the OpenMC Monte Carlo computational kernel on CPU, and AMD and NVIDIA GPUs and, ii) RIOPA.jl, a Julia proxy application designed to mimic parallel I/O application characteristics and payloads. In particular, we are interested in the feasibility of using Julia as a HPC language, similar to Fortran, C and C++, by evaluating the current state and integration with HPC heterogenous programming models and backends: MPI.jl, Julia’s Base Threads, GPU programming: CUDA.jl, AMDGPU.jl and KernelAbstractions.jl; parallel I/O: HDF5.jl and ADIOS2.jl; and the portability of the resulting Julia proxy application across heterogeneous systems. We will share with the Julia community the current challenges, gaps and highlight potential opportunities to balance the trade-offs between programmer productivity and performance in a HPC environment as we prepare for the exascale era in supercomputing. Our goal is to showcase the value added by the Julia language in our early work constructing proxy apps for rapid prototyping as part of our efforts in the U.S. DOE Exascale Computing Project (ECP).