Earliest Eligible Virtual Deadline First (EEVDF) Scheduling in Linux

From 2007 until the release of the Linux kernel 6.6, the Completely Fair Scheduler (CFS) was responsible for managing CPU time across processes. However, despite its name, it was not truly "completely fair"—over time, numerous patches were introduced to enhance its functionality and improve its handling of various scenarios.

Although CFS managed process fairness reasonably well, it was not inherently designed to handle properties such as latency. This was particularly relevant for processes that required minimal CPU time but needed it promptly when they did.

With Linux 6.6, the Earliest Eligible Virtual Deadline First (EEVDF) scheduler was introduced as a long-awaited successor to CFS. It was designed to replace the latency-nice patches for CFS while simplifying the scheduler code. Where CFS relied on latency-nice patches to address latency, EEVDF was designed to provide this functionality natively, without additional patches.

In this presentation, the EEVDF scheduler will be introduced, its functionality and underlying algorithm explained and compared against CFS.