Just crossed this interesting post on Oracle’s blog on Enterprise Manager. When you are in to optimizing your JVMs you might want to take a look at it….

Tuning a production JVM involves more than merely adding more RAM to it via the -Xmx parameter. It depends upon an understanding of how your application truly behaves in a production environment. Most JVM tuning is done by developers with a simulated load in their Development or QA environment. This is unlikely to be truly representative of the production load running on production hardware with regards to proper JVM tuning.

Using JVM Diagnostics (JVMD) to help tune production JVMs