一句话：提出 Plugsched，通过模块化与状态重建实现 Linux 内核调度器整体在线更新，停机时间低于数十毫秒。
生产云环境承载多种负载，需要不同调度器，但在不重启 OS 的情况下整体更新 Linux 调度器十分困难；现有细粒度函数级热更新或微内核方案无法更新整个重型调度子系统。本文提出 Plugsched：首先以模块化思想将调度器与 Linux 内核解耦为独立模块，其次用数据重建技术把旧调度器状态迁移到新调度器，并引入优化栈检查以降低更新停机时间。该方案无需修改内核代码，即可更新整个调度器子系统并修改内部数据。实验与生产结果表明，Plugsched 能有效在线更新内核调度器，停机时间小于数十毫秒。
The scheduler is a critical component of the operating system (OS)and is tightly coupled with Linux. Production-level clouds often host various workloads, and these workloads require different schedulers to achieve high performance. Thus the capability of updating the scheduler lively without rebooting the OS is crucial for the production environments. However, emerging live update techniques only apply for the fine-grained function-level updates or require extra constraints such as microkernel. It fails to update the entire heavy process scheduler subsystem lively. We therefore propose Plugsched to enable scheduler live update, and there are two key novelties. First of all, with the idea of modularization, Plugsched decouples the scheduler from the Linux kernel to be an independent module; Secondly, Plugsched uses the data rebuild technique to migrate the state from the old scheduler to the new one. This scheme can be directly applied to the Linux kernel scheduler in production environments without modifying kernel code. Unlike current function-level live update solutions, Plugsched allows developers to update the entire scheduler subsystem and modify internal scheduler data via the rebuilding technique. Moreover, an optimized stack inspection method is introduced to further effectively reduce the downtime due to the update. Experimental and production results show that Plugsched can effectively update kernel scheduler lively and the downtime is less than tens of milliseconds.
@inproceedings{paperbot10085,
title = {Efficient Scheduler Live Update for Linux Kernel with Modularization},
author = {Teng Ma and Shanpei Chen and Yihao Wu and Erwei Deng and Zhuo Song and Quan Chen and Minyi Guo},
booktitle = {ASPLOS},
year = {2023},
doi = {10.1145/3582016.3582054}
}