Towards High Performance Resilience Using Performance Portable Abstractions

Abstract

In the drive towards Exascale, the extreme heterogeneity of supercomputers at all levels places a major development burden on HPC applications. To this end, performance portable abstractions such as those advocated by Kokkos, RAJA and HPX are becoming increasingly popular. At the same time, the unprecedented scalability requirements of such heterogeneous components means higher failure rates, motivating the need for resilience in systems and applications. Unfortunately, state-of-art resilience techniques based on checkpoint/restart are lagging behind performance portability efforts: users still need to capture consistent states manually, which introduces the need for fine-tuning and customization. In this paper we aim to close this gap by introducing a set of abstractions that make it easier for the application developers to reason about resilience. To this end, we extend the existing abstractions proposed by performance portability efforts towards resilience. By marking critical data structures that need to be checkpointed, one can enable an optimized runtime to automate checkpoint-restart using high performance and scalable asynchronously techniques. We illustrate the feasibility of our proposal using a prototype that combines the Kokkos runtime (HPC performance portability), with the VELOC runtime (large-scale low overhead checkpoint-restart). Our experimental results show negligible performance overhead compared compared with a manually tuned implementation of checkpoint-restart while requiring minimal changes in the application code.

Integrating process, control-flow, and data resiliency layers using a hybrid Fenix/Kokkos approach

“…The control-flow resilience layer is a newer focus of research. Kokkos Resilience [8], [15] and Resilient HCLIB [16] both utilize existing parallel control libraries to manage control-flow during recovery, which benefits from preexisting knowledge of the application's default control-flow. The two implement resilience methods in parallel-region and asynchronous-many-task runtimes, respectively.…”

“…We present a comprehensive resilience system runtime which integrates process resilience, control-flow resilience, and data resilience. Out implementation uses Fenix for the process resilience component, Kokkos Resilience [8] for controlflow resilience component, and VeloC [9] for data resilience. The result of this is a highly performant, comprehensive resilience environment consisting of runtimes that offer support for a wide array of state-of-the-art resilience strategies.…”