A comprehensive dynamic tracing framework originating from the Solaris Operating Environment.
DTrace is a comprehensive dynamic tracing framework for the Solaris Operating Environment; it provides a powerful infrastructure to permit administrators, developers, and service personnel to concisely answer arbitrary questions about the behavior of the operating system and user programs.
DTrace can be used to get a global overview of a running system, such as the amount of memory, CPU time, file-system and network resources used by the active processes. It can also provide much more fine-grained information, such as a log of the arguments with which a specific function is being called, or a list of the processes accessing a specific file.
(Source: http://en.wikipedia.org/wiki/Dtrace)
