I just came across a great site with lots of papers related to performance monitoring and tuning for Linux:

http://www.ufsdump.org

One paper I especially liked:

Extreme Linux Performance Monitoring And Tuning

"The purpose of this document is to describe how to monitor Linux operating systems for performance.  This paper examines how to interpret common Linux performance tool output.  After collecting this output, the paper describes how to make conclusions about performance bottlenecks."

Lots of great info!