Linux vs. Lightweight Multi-Kernels for High-Performance Computing: Experiences at Pre-Exascale

Authors: Balazs Gerofi (RIKEN); Kohei Tarumizu, Lei Zhang, and Takayuki Okamoto (Fujitsu Ltd); Masamichi Takagi (RIKEN); Shinji Sumimoto (Fujitsu Ltd); and Yutaka Ishikawa (RIKEN)

Abstract: The long standing consensus in the High-Performance Computing (HPC) Operating Systems (OS) community is that lightweight kernel-based OSes (LWKs) have the potential to outperform Linux at extreme scale. To explore if LWKs live up to their expectation we developed IHK/McKernel, a lightweight multi-kernel OS designed for HPC, and deployed it on two high-end supercomputers to compare its performance against Linux. Oakforest-PACS, an Intel Xeon Phi-based supercomputer, runs a moderately tuned Linux distribution. Fugaku is based on Fujitsu's A64FX CPU that runs a highly tuned Linux environment.

We discuss some of the recent developments in our OS and provide a detailed description on the challenges of tuning Fugaku's Linux for HPC. While in a moderately tuned environment McKernel significantly outperforms Linux, on Fugaku we observe an average of 4% speedup (across all our experiments), with only a few exceptions where the LWK outperforms Linux by up to 25%.




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