Mitigating excessive vCPU spinning in VM-Agnostic KVM

Kenta Ishiguro, Naoki Yasuno, Pierre Louis Aublin, Kenji Kono

研究成果: Conference contribution

抄録

In virtualized environments, oversubscribing virtual CPUs (vCPUs) on physical CPUs (pCPUs) is common to utilize CPU resources efficiently. Unfortunately, excessive vCPU spinning, which occurs when a vCPU is waiting in a spin loop for an event from a descheduled vCPU, causes serious performance degradation. Usually, the VM-Agnostic hypervisor tries to prevent excessive vCPU spinning by rescheduling vCPUs when an excessive spin is detected by hardware support for virtualization. This paper investigates the effectiveness of KVM vCPU scheduler and shows it fails to avoid excessive vCPU spinning in many opportunities. Our in-depth analysis reveals simple modifications to KVM (41 LOC) improve the mitigation of excessive vCPU spinning. We have identified three problems: 1) scheduler mismatch, 2) lost opportunity, and 3) overboost. The first problem comes from the mismatch between the KVM vCPU scheduler and the Linux scheduler. The second and third problems come from an inefficient algorithm for choosing the next candidate vCPU to be scheduled. Our simple modifications gracefully resolves the problems and the performance improves by up to 80 %. Our results imply the VM-Agnostic hypervisor can resolve excessive vCPU spinning more gracefully than previously believed.

本文言語English
ホスト出版物のタイトルVEE 2021 - Proceedings of the 17th ACM SIGPLAN/SIGOPS International Conference on Virtual Execution Environments
編集者Ben L. Titzer, Harry Xu, Irene Zhang
出版社Association for Computing Machinery, Inc
ページ139-152
ページ数14
ISBN(電子版)9781450383943
DOI
出版ステータスPublished - 2021 4 16
イベント17th ACM SIGPLAN/SIGOPS International Conference on Virtual Execution Environments, VEE 2021 - Virtual, Online, United States
継続期間: 2021 4 162021 4 16

出版物シリーズ

名前VEE 2021 - Proceedings of the 17th ACM SIGPLAN/SIGOPS International Conference on Virtual Execution Environments

Conference

Conference17th ACM SIGPLAN/SIGOPS International Conference on Virtual Execution Environments, VEE 2021
国/地域United States
CityVirtual, Online
Period21/4/1621/4/16

ASJC Scopus subject areas

  • 人工知能
  • ソフトウェア

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