IBM has a decent reference on tuning, in the process delving a little bit under the hood of Linux, and at the end of the doc providing quite a bit of excellent "additional reading": http://www.redbooks.ibm.com/abstracts/REDP3861.html - while it's got RH & IBM xSeries in the title, it really has some good overall info - rivaling some texts I've seen for $$$$. Don