The kernel leaves NVMe on none and everything else on mq-deadline. Neither
bounds latency once the device queue fills, so a large build, copy, or
package upgrade can make the desktop sluggish while reads wait behind a
wall of writes.
Kyber keeps separate read and sync-write queues and throttles the depth it
submits to hit a 2ms read target, which keeps interactive reads flowing
under heavy writes at negligible CPU cost. The trade is a small ceiling on
peak throughput on very fast devices, which matters for a storage server
chasing IOPS but not for a desktop.
Ships as a package-owned udev rule in /etc so it applies at boot and on
hot-plug. Existing installs pick it up at the next boot. zram is left alone
since it has nothing to schedule.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
