Linux-Kernel: CFQ-Scheduling and ionice...

Everyone, who uses computers, has experienced a hanging system. Sometimes this is due to high cpu usage, but often it is due to i/o contention.
Now with Linux 2.6 kernels there is this parameter "elevator":

elevator= [IOSCHED]
Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
See Documentation/block/as-iosched.txt and
Documentation/block/deadline-iosched.txt for details.

Choosing CFQ solve this problem, if you aware of ionice. With ionice i/o can be prioritized using classes.
For example:

ionice -c3 myprogram

The only problem is, that ps or top does not support this ionice parameter. So you have to ask for each process the ioniceness via ionice -p PID:

$ ionice -p 6344
none: prio 0