Change the Xen scheduler

Q: I am experiencing a heavy slowdown of the entire dom0 and all other domUs if *one* domU gets under heavy load.Is there any way to tighten this domU by adjusting something like scheduling?
A: You can use elevator=cfq as the command line option for both the dom0 and domU kernels in grub.conf and /etc/xen domU config files respectively. This will force the use of cfq as the default scheduler. By default anticipatory is the scheduler in dom0 and noop in domU. Alternatively:

echo "cfq" > /sys/block/sda/queue/scheduler