From Fedora Project Wiki
Ok, so you have installed the real time kernel form Planet CCRMA but you feel that something is still compromising your low latency objectives. Well, this is touchy subject and it does have many variables, but with some research and some useful tools, you will gain the knowledge to have your Fedora machine running with acceptable latencies.
Tools
There are a two tools that I use to further fine tune my system for real time audio use.
The first one is the realtimeconfigquickscan. You can download it here: http://code.google.com/p/realtimeconfigquickscan/ [1]