What is "systemtap"

In computing, SystemTap (stap) is a scripting language and tool for dynamically instrumenting running production Linux kernel-based operating systems. System administrators can use SystemTap to extract, filter and summarize data in order to enable diagnosis of complex performance or functional problems.

SystemTap consists of free and open-source software and includes contributions from Red Hat, IBM, Intel, Hitachi, Oracle, and other community members.