High CPU Utilization When Copying to Ext4

[Mccauliff, Sean D. (ARC-PX)[Lockheed Martin Space OPNS]]

Sorry if this is not the correct mailing list for ext4 questions.

I'm copying terabytes of data from an ext3 file system to a new ext4 file system.  I'm seeing high CPU usage from the processes  flush-253:2, kworker-3:0, kworker-2:2, kworker-1:1, and kworker-0:0.   Does anyone on the list have any idea what these processes do, why they are consuming so much cpu time and if there is something that can be done about it?  This is using Fedora 15.

Thanks!
Sean