Fedora Developers Are Trying To Figure Out The Best Linux I/O Scheduler
Written by Michael Larabel in Fedora on 14 December 2018 at 12:09 PM EST. 23 Comments
FEDORA --
Fedora developers are working on trying to figure out the best default behavior moving forward for their I/O scheduler selection.

With the multi-queue I/O queuing mechanism (BLK-MQ) stabilizing and ready to be the default with the legacy I/O code potentially being removed in a coming kernel release, Fedora developers and users are trying to figure out what is the best I/O scheduler to use as the default for their distribution.

The primary contenders are between none (suitable for high-end NVMe SSDs), the MQ-Deadline that some Linux distributions default to, or BFQ as the promising Budget Fair Queuing scheduler that has a dedicated following and can work quite well for a responsive Linux desktop in its low-latency mode. There is also Kyber as the Facebook-developed BLK-MQ I/O scheduler, but there doesn't seem to be much interest in making that Fedora's default -- and in my own tests, Kyber usually performs the worst of the above mentioned alternatives.

See my recent Linux 4.20 I/O scheduler benchmarks for some recent performance numbers on these different scheduling options and some other numbers from 4.19.

At this point there doesn't appear to be a clear consensus about what I/O scheduler would be best for Fedora moving forward, but we'll see where this discussion heads over the days/weeks ahead. Those wishing to follow this discussion can find it on Fedora's devel list.
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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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