I/O scheduler

The kernel component that decides the order in which queued disk requests are sent to a device.

In more detail

Each block device has one, chosen in /sys/block/NAME/queue/scheduler: mq-deadline favours fairness and latency, bfq favours interactive desktops, and none passes requests straight through, which suits fast NVMe drives. A change there lasts until the next boot.

Example

cat /sys/block/vda/queue/scheduler

Taught in

• Storage Performance: Busy, Slow, Or Both — Linux Foundation Certified System Administrator (LFCS) Exam Prep

References

• Linux kernel documentation: switching I/O schedulers

Certification courses

• LFCS course and practice exam: Linux Foundation Certified System Administrator