Patches Published Again For Replacing Linux Kernel's CFQ With BFQ
Written by Michael Larabel in Linux Kernel on 4 February 2016 at 07:18 AM EST. 16 Comments
A set of 22 patches were published this week that seek to replace the Linux kernel's default I/O scheduler CFQ (Completely Fair Queueing) with BFQ, the Budget Fair Queueing.

Paolo Valente sent out the latest patch series under a "request for comments" thread via the Replace the CFQ I/O Scheduler with BFQ thread. Paolo explained, "this patchset replaces CFQ with the last version of BFQ (which is a proportional-share I/O scheduler). To make a smooth transition, this patchset first brings CFQ back to its state at the time when BFQ was forked from CFQ. Basically, this reduces CFQ to its engine, by removing every heuristic and improvement that has nothing to do with any heuristic or improvement in BFQ, and every heuristic and improvement whose goal is achieved in a different way in BFQ. Then, the second part of the patchset starts by replacing CFQ's engine with BFQ's engine, and goes on by adding current BFQ improvements and extra heuristics."

On the BFQ site their results show BFQ performing significantly better than CFQ, Deadline, and Noop I/O schedulers for various storage mediums. BFQ aims to provide low-latency for interactive applications, low-latency for soft real-time applications, a high throughput (the claim is 30% higher than CFQ), and strong fairness guarantees.

BFQ is patched in and used by some distributions like Manjaro, Sabayon, and OpenMandriva, but the goal here is for it to be mainlined and completely replace CFQ. However, given that these patches were sent out three days ago and haven't yet been commented on by other upstream kernel developers, it doesn't look likely that this work will get merged anytime soon; this BFQ effort has already been ongoing for several years.
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