He posted almost all basics you should know about different types of GCs, how to enable them in HotSpot JVM and most importantly when to enable them.
Just go there and read it!
This blog is dedicated to all Java developers. I'm trying to present my everyday problems I encounter developing complicated systems and my solutions to these problems. Java EE topics are also covered (JMS, JAAS, JCE, TIBCO EMS, Tomcat, etc.) This blog extends it's subject range also to Agile Software Development frameworks like Scrum and XP (eXtreme Programming).