Completely Fair Queuing (CFQ) is an I/O scheduler for the Linux kernel which was written in 2003 by Jens Axboe.
The length of the time slice and the number of requests a queue is allowed to submit depends on the I/O priority of the given process.
In February 2003 Andrea Arcangeli put forward his idea for a Stochastic Fair Queueing I/O scheduler to Jens Axboe who then implemented it.
Jens Axboe made improvements to his first implementation, calling the new version the Completely Fair Queueing scheduler, and produced a patch to apply it to the 2.5.60 development series kernel.
Red Hat Enterprise Linux 4 used this I/O scheduler as the default even though it used a kernel based on a 2.6.9.