bfq
also: Budget Fair Queueing
BFQ (Budget Fair Queueing) is an I/O scheduler for Linux that prioritizes fairness and responsiveness by allocating disk bandwidth fairly among processes, preventing any single process from starving others.
BFQ is a modern block I/O scheduler in the Linux kernel that manages how disk read and write requests are queued and executed. Unlike older schedulers that prioritize throughput, BFQ focuses on fairness and system responsiveness by ensuring that each process gets a fair share of disk bandwidth.
BFQ works by assigning each process a "budget" of I/O operations and switching between processes in a way that prevents any single heavy I/O workload from monopolizing the disk. This makes the system feel more responsive during intensive disk activity—for example, your system remains snappy when running a large file copy in the background.
You can check which I/O scheduler is active with cat /sys/block/sda/queue/scheduler and switch to BFQ using echo bfq > /sys/block/sda/queue/scheduler. BFQ is particularly beneficial on SSDs and for desktop/interactive workloads, though it may reduce peak throughput compared to simpler schedulers like noop.