KernelTrap: Time Sliced CFQ With IO Priorities

"Jens Axboe offered a patch that introduces basic IO priority support for his time sliced CFQ IO scheduler. Similar in concept to nice values for the process scheduler, Jens's patch offers '8 basic io priorities now, 0 being [the] highest prio and 7 the lowest.' However, whereas nice values adjust a process's priority to CPU cycles, the IO priority value adjusts a process's priority to disk IO. With all processes running at the same IO priority, they will all average the same disk access rate. With process running at different priorities, the lower the IO priority value the faster they will access the disk, though the total aggregate bandwidth will always stay the same..."

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