jtreg documentation doesn't describe the test mode options (such as agentvm) in much detail, so it's not clear when to use which one and what restrictions might exist. http://openjdk.java.net/jtreg/command-help.html gives a bit of information about their meaning, but no information about why one would choose one over another. http://openjdk.java.net/jtreg/runtests.html refers to a blog post (See jtreg: old and new for a blog entry giving details of the different execution modes.), but the link is dead. Similarly other blog links at http://openjdk.java.net/jtreg/resources.html. (I wonder who thought breaking all blog links was a good idea?)