The Linux Trace Toolkit (LTT) is a set of tools that is designed to log program execution details from a patched Linux kernel and then perform various analyses on them, using console-based and graphical tools. LTT has been mostly superseded by its successor
LTTng
LTTng (Linux Trace Toolkit: next generation) is a system software package for correlated tracing of the Linux kernel, applications and libraries. The project was originated by Mathieu Desnoyers with an initial release in 2005. Its predecessor is ...
(Linux Trace Toolkit Next Generation).
LTT allows the user to see in-depth information about the processes that were running during the trace period, including when context switches occurred, how long the processes were blocked for, and how much time the processes spent executing vs. how much time the processes were blocked. The data is logged to a text file and various console-based and graphical (
GTK+
GTK (formerly GIMP ToolKit and GTK+) is a free and open-source cross-platform widget toolkit for creating graphical user interfaces (GUIs). It is licensed under the terms of the GNU Lesser General Public License, allowing both free and proprie ...
) tools are provided for interpreting that data.
In order to do data collection, LTT requires a patched Linux kernel. The authors of LTT claim that the performance hit for a patched kernel compared to a regular kernel is minimal; Their testing has reportedly shown that this is less than 2.5% on a "normal use" system (measured using batches of kernel makes) and less than 5% on a file I/O intensive system (measured using batches of tar).
Usage
Collecting trace data
Data collection is Started by:
trace 15 foo
This command will cause the LTT tracedaemon to do a trace that lasts for 15 seconds, writing trace data to
foo.trace and process information from the
/proc filesystem to
foo.proc.
The
trace command is actually a script which runs the program
tracedaemon with some common options. It is possible to run
tracedaemon directly and in that case, the user can use a number of command-line options to control the data which is collected. For the complete list of options supported by
tracedaemon, se
the online manual page for tracedaemon
Viewing the results
Viewing the results of a trace can be accomplished with:
traceview foo
This command will launch a graphical (
GTK+
GTK (formerly GIMP ToolKit and GTK+) is a free and open-source cross-platform widget toolkit for creating graphical user interfaces (GUIs). It is licensed under the terms of the GNU Lesser General Public License, allowing both free and proprie ...
)
traceview tool that will read from
foo.trace and
foo.proc. This tool can show information in various interesting ways, including Event Graph, Process Analysis, and Raw Trace. The Event Graph is perhaps the most interesting view, showing the exact timing of events like
page fault
In computing, a page fault (sometimes called PF or hard fault) is an exception that the memory management unit (MMU) raises when a process accesses a memory page without proper preparations. Accessing the page requires a mapping to be added to t ...
s,
interrupt
In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted, ...
s, and
context switch
In computing, a context switch is the process of storing the state of a process or thread, so that it can be restored and resume execution at a later point, and then restoring a different, previously saved, state. This allows multiple processes ...
es, in a simple graphical way.
The
traceview command is a wrapper for a program called
tracevisualizer. For the complete list of options supported by
tracevisualizer, se
the online manual page for tracevisualizer
See also
*
Performance analysis
References
*
*
External links
LTT page at Opersys.comLTT page at Ecole Polytechnique de Montreal
{{Linux
Linux programming tools
Programming tools