Reduce data pump rate

I want to reduce the load caused by a data pump job on the system, mostly on I/O but on CPU as well. RMAN provides a way to intentionally reduce backup speed (keywords: duration, minimize load). Data pump doesn't provide such option. I'm thinking of messing with the process from the OS. (Let's say the OS is Linux.) Alternatively, I may be able to provide a query clause to the data pump command such that the query sometimes stalls for a subsecond. Or use database Resource Manager, but not sure how to throttle on I/O. What do you suggest?