Completely Fair Scheduler Analyzed

Jan 17, 2008

Jan Rähm

Avinesh Kumar, an IBM developer has taken a close look at the Completely Fair Scheduler (CFS) introduced with kernel 2.6.23, comparing it with other schedulers. In the conclusion to the analysis, Kumar discusses changes in the future kernel 2.6.24 scheduler.

In the document Kumar compares the Completely Fair Scheduler with the Rotating Staircase Deadline Scheduler, developed by Australian anesthetist Con Colivas. Some of Colivas's RSD scheduler code was used for the current scheduler. After an introduction to the Pluggable CPU Scheduler kernel framework, which is useful for testing applications, Kumar describes the scheduler's logic.

Kumar concludes the article by discussing the changes to the scheduler for kernel 2.6.24, which is due for release in the near future. Besides optimizations for individual applications, there are some improvements relating to group policies.

The document is available free of charge from IBM's developer pages along with many other documents on the kernel and its subsystems.

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