Using Unused: Non-Invasive Dynamic FaaS Infrastructure with HPC-Whisk

TL;DR

This paper presents a non-invasive FaaS infrastructure that leverages idle HPC nodes using Slurm and OpenWhisk, achieving up to 90% coverage of idle time without impacting HPC performance.

Contribution

It introduces a novel dynamic FaaS system on HPC clusters that efficiently utilizes idle nodes without disrupting existing workloads.

Findings

Covered up to 90% of idle time slots on a 50k-core cluster

Integrated Slurm and OpenWhisk for dynamic resource management

Maintained HPC performance while deploying FaaS functions

Abstract

Modern HPC workload managers and their careful tuning contribute to the high utilization of HPC clusters. However, due to inevitable uncertainty it is impossible to completely avoid node idleness. Although such idle slots are usually too short for any HPC job, they are too long to ignore them. Function-as-a-Service (FaaS) paradigm promisingly fills this gap, and can be a good match, as typical FaaS functions last seconds, not hours. Here we show how to build a FaaS infrastructure on idle nodes in an HPC cluster in such a way that it does not affect the performance of the HPC jobs significantly. We dynamically adapt to a changing set of idle physical machines, by integrating open-source software Slurm and OpenWhisk. We designed and implemented a prototype solution that allowed us to cover up to 90\% of the idle time slots on a 50k-core cluster that runs production workloads.