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- <title>Linux Trace Toolkit Quickstart</title>
+ <title>Linux Trace Toolkit Next Generation User Documentation</title>
</head>
<body>
-<h1>Linux Trace Toolkit Quickstart</h1>
+<h1>Linux Trace Toolkit Next Generation User Documentation</h1>
Author : Mathieu Desnoyers, September 2005<br>
Last update : January 21st, 2009<br>
+(originally known as the LTTng QUICKSTART guide)
<h2>Table of Contents</h2>
-<ul>
+<ul>
<li><a href="#intro" name="TOCintro">Introduction</a></li>
+<ul>
+<li><a href="#arch" name="TOCarch">Supported architectures</a></li>
+</ul>
+
<li><a href="#section1" name="TOCsection1">Installing LTTng and LTTV from
sources</a></li>
+<ul>
+<li><a href="#prerequisites" name="TOCprerequisites">Prerequisistes</li>
+<li><a href="#getlttng" name="TOCgetlttng">Getting the LTTng packages</li>
+<li><a href="#getlttngsrc" name="TOCgetlttngsrc">Getting the LTTng kernel sources</li>
+<li><a href="#installlttng" name="TOCinstalllttng">Installing a LTTng kernel</li>
+<li><a href="#editconfig" name="TOCeditconfig">Editing the system wide
+configuration</a>
+<li><a href="#getlttctl" name="TOCgetlttctl">Getting and installing the
+ltt-control package</li>
+<li><a href="#userspacetracing" name="TOCuserspacetracing">Userspace Tracing</li>
+<li><a href="#getlttv" name="TOCgetlttv">Getting and installing the LTTV package</ul>
+
<li><a href="#section2" name="TOCsection2">Using LTTng and LTTV</a></li>
+<ul>
+<li><a href="#uselttvgui" name="TOCuselttvgui">Use graphical LTTV to control
+tracing and analyse traces</a></li>
+<li><a href="#uselttngtext" name="TOCuselttngtext">Use text mode LTTng to
+control tracing</a></li>
+<li><a href="#uselttvtext" name="TOCuselttvtext">Use text mode LTTV</a></li>
+<li><a href="#hybrid" name="TOChybrid">Tracing in "Hybrid" mode</a></li>
+<li><a href="#flight" name="TOCflight">Tracing in flight recorder mode</a></li>
+</ul>
+
<li><a href="#section3" name="TOCsection3">Adding kernel and user-space
-tracepoints</a></li>
+instrumentation</a>
+<ul>
+<li><a href="#kerneltp" name="TOCkerneltp">Adding kernel instrumentation</a></li>
+<li><a href="#usertp" name="TOCusertp">Adding userspace instrumentation</a></li>
+</ul>
+
<li><a href="#section4" name="TOCsection4">Creating Debian and RPM packages
-from LTTV</a>
+from LTTV</a></li>
+<ul>
+<li><a href="#pkgdebian" name="TOCpkgdebian">Create custom LTTV Debian
+<li><a href="#pkglttng" name="TOCpkglttng">Create custom LTTng packages</a></li>
+</ul>
+
+<li><a href="#section5" name="TOCsection5">Examples of LTTng use in the
+field</a></li>
</ul>
<h2><a href="#TOCintro" name="intro">Introduction</a></h2>
<p>
-This document is made of four parts : the first one explains how
+This document is made of five parts : the first one explains how
to install LTTng and LTTV from sources, the second one describes the steps
to follow to trace a system and view it. The third part explains
briefly how to add a new trace point to the kernel and to user space
-applications. The fourth and last part explains how to create Debian or RPM
-packages from the LTTng and LTTV sources.
-
+applications. The fourth part explains how to create Debian or RPM
+packages from the LTTng and LTTV sources. The fifth and last part describes use
+of LTTng in the field.
<p>
These operations are made for installing the LTTng 0.86 tracer on a linux 2.6.X
kernel. You will also find instructions for installation of LTTV 0.12.x : the
refer to :
<a
href="http://ltt.polymtl.ca/svn/trunk/lttv/doc/developer/lttng-lttv-compatibility.html">LTTng+LTTV versions compatibility</a>
-The lttng patch is necessary to have the tracing hooks in the kernel.
+
+The ongoing work had the Linux Kernel Markers integrated in the mainline Linux
+kernel since Linux 2.6.24 and the Tracepoints since 2.6.28. In its current
+state, the lttng patchset is necessary to have the trace clocksource, the
+instrumentation and the LTTng high-speed data extraction mechanism added to the
+kernel.
<br>
<br>
-Supported architectures :
+<h3><a href="#TOCarch" name="arch">Supported architectures</a></h3>
<br>
LTTng :<br>
+<br>
<li> x86 32/64 bits
<li> PowerPC 32 and 64 bits
<li> ARM (with limited timestamping precision, e.g. 1HZ. Need
architecture-specific support for better precision)
<li> MIPS
+<li> sh (partial architecture-specific instrumentation)
+<li> sparc64 (partial architecture-specific instrumentation)
+<li> s390 (partial architecture-specific instrumentation)
+<li> Other architectures supported without architecture-specific instrumentation
+and with low-resolution timestamps.<br>
<br>
<br>
LTTV :<br>
+<br>
<li> Intel 32/64 bits
<li> PowerPC 32 and 64 bits
<li> Possibly others. Takes care of endianness and type size difference between
<hr />
-<h2><a href="#TOCsection2" name="section2">Installation from sources</a></h2>
+<h2><a href="#TOCsection1" name="section1">Installation from sources</a></h2>
<p>
-<li>Prerequisites</li>
+<h3><a href="#TOCprerequisites" name="prerequisites">Prerequisites</a></h3>
<ul>
<p>
Tools needed to follow the package download steps :
versions compatibility</a>.
-<li>Getting the LTTng packages</li>
+<h3><a href="#TOCgetlttng" name="getlttng">Getting the LTTng packages</a></h3>
<PRE>
su -
</PRE>
-<li>Getting LTTng kernel sources</li>
+<h3><a href="#TOCgetlttngsrc" name="getlttngsrc">Getting LTTng kernel sources</a></h3>
<PRE>
su -
</PRE>
-<li>Installing a LTTng kernel</li>
+<h3><a href="#TOCinstalllttng" name="installlttng">Installing a LTTng kernel</a></h3>
<PRE>
su -
--
</PRE>
-<li>Editing the system wide configuration</li>
+<h3><a href="#TOCeditconfig" name="editconfig">Editing the system wide
+configuration</a></h3>
<p>
You must activate debugfs and specify a mount point. This is typically done in
#echo lockdep-trace >> /etc/modules
</PRE>
-<li>Getting and installing the ltt-control package (on the traced machine)</li>
+
+<h3><a href="#TOCgetlttctl" name="getlttctl">Getting and installing the
+ltt-control package (on the traced machine)</a></h3>
<p>
(note : the ltt-control package contains lttd and lttctl. Although it has the
same name as the ltt-control kernel module, they are *not* the same thing.)
make install
</PRE>
-<li>Userspace tracing</li>
+<h3><a href="#TOCuserspacetracing" name="userspacetracing">Userspace tracing</a></h3>
<PRE>
Make sure you selected the kernel menuconfig option :
event name : event
</PRE>
-<li>Getting and installing the LTTV package (on the visualisation machine, same
-or different from the visualisation machine)</li>
+<h3><a href="#TOCgetlttv" name="getlttv">Getting and installing the LTTV package
+(on the visualisation machine, same
+or different from the visualisation machine)</a></h3>
<PRE>
su -
./configure
make
make install
-
-
-<li>Getting and installing the markers-userspace package for user space
-tracing (experimental)</li>
-
-See <a
-href="http://ltt.polymtl.ca/packages/markers-userspace-0.5.tar.bz2">markers-userspace-0.5.tar.bz2</a> or more recent.
+</PRE>
<hr />
-<h2><a href="#TOCsection3" name="section3">Using LTTng and LTTV</a></h2>
-
-<li>IMPORTANT : Arm Linux Kernel Markers after each boot</li>
+<h2><a href="#TOCsection2" name="section2">Using LTTng and LTTV</a></h2>
+<li><b>IMPORTANT : Arm Linux Kernel Markers after each boot before tracing</b></li>
<PRE>
ltt-armall
</PRE>
-<li>Use graphical LTTV to control tracing and analyse traces</li>
-
+<h3><a href="#TOCuselttvgui" name="uselttvgui">Use graphical LTTV to control
+tracing and analyse traces</a></h3>
<PRE>
lttv-gui (or /usr/local/bin/lttv-gui)
- Spot the "Tracing Control" icon : click on it
* You should now see a trace
</PRE>
-<li>Use text mode LTTng to control tracing</li>
+<h3><a href="#TOCuselttngtext" name="uselttngtext">Use text mode LTTng to control tracing</a></h3>
<PRE>
The tracing can be controlled from a terminal by using the lttctl command (as
root).
lttctl -D trace1
see lttctl --help for details.
-<PRE>
+</PRE>
<p>
(note : to see if the buffers has been filled, look at the dmesg output after
lttctl -R or after stopping tracing from the GUI, it will show an event lost
how. lttv now also shows event lost messages in the console when loading a trace
with missing events or lost subbuffers.)
-<li>Use text mode LTTV</li>
+<h3><a href="#TOCuselttvtext" name="uselttvtext">Use text mode LTTV</a></h3>
<p>
Feel free to look in /usr/local/lib/lttv/plugins to see all the text and
graphical plugins available.
<p>
For example, a simple trace dump in text format is available with :
-
<PRE>
lttv -m textDump -t /tmp/trace
</PRE>
-
<p>
See lttv -m textDump --help for detailed command line options of textDump.
-
<p>
It is, in the current state of the project, very useful to use "grep" on the
text output to filter by specific event fields. You can later copy the timestamp
bottom right label "Current time". Support for this type of filtering should
be added to the filter module soon.
-<li>Hybrid mode</li>
-
+<h3><a href="#TOChybrid" name="hybrid">Tracing in "Hybrid" mode</a></h3>
<p>
Starting from LTTng 0.5.105 and ltt-control 0.20, a new mode can be used :
hybrid. It can be especially useful when studying big workloads on a long period
of time.
-
<p>
When using this mode, the most important, low rate control information will be
recorded during all the trace by lttd (i.e. process creation/exit). The high
rate information (i.e. interrupt/traps/syscall entry/exit) will be kept in a
flight recorder buffer (now named flight-channelname_X).
-
<p>
The following lttctl commands take an hybrid trace :
<p>
<p>
Each "overwrite" channel is flight recorder channel.
-<li>Flight recorder mode</li>
+<h3><a href="#TOCflight" name="flight">Tracing in flight recorder mode</a></h3>
+<li>Flight recorder mode</li>
<p>
The flight recorder mode writes data into overwritten buffers for all channels,
including control channels, except for the facilities tracefiles. It consists of
setting all channels to "overwrite".
-
<p>
The following lttctl commands take a flight recorder trace :
-
<PRE>
lttctl -C -w /tmp/trace3 -o channel.all.overwrite=1 trace3
...
lttctl -D -w /tmp/trace3 trace3
</PRE>
-**************************************************************
-** Section 4 * Adding new instrumentations with the markers **
-**************************************************************
+<hr />
+
-See Documentation/markers.txt and Documentation/tracepoints.txt in your kernel
+<h2><a href="#TOCsection3" name="section3">Adding new instrumentations with the
+markers</a></h2>
+<p>
+
+<h3><a href="#TOCkerneltp" name="kerneltp">Adding kernel
+instrumentation</a></h3>
+
+<p>
+See <a
+href="http://git.kernel.org/?p=linux/kernel/git/compudj/linux-2.6-lttng.git;a=blob;f=Documentation/markers.txt">Documentation/markers.txt</a>
+and <a
+href="http://git.kernel.org/?p=linux/kernel/git/compudj/linux-2.6-lttng.git;a=blob;f=Documentation/tracepoints.txt">Documentation/tracepoints.txt</a> in your kernel
tree.
+<p>
+Also see <a
+href="http://git.kernel.org/?p=linux/kernel/git/compudj/linux-2.6-lttng.git;a=tree;f=ltt/probes">ltt/probes/</a>
+for LTTng probe examples.
-* Add new events to userspace programs with userspace markers
-http://ltt.polymtl.ca/packages/
+<h3><a href="#TOCusertp" name="usertp">Adding userspace instrumentation</a></h3>
+Add new events to userspace programs with
+<a href="http://ltt.polymtl.ca/packages/">userspace markers packages</a>.
Get the latest markers-userspace-*.tar.bz2 and see the Makefile and examples. It
allows inserting markers in executables and libraries, currently only on x86_32
and x86_64.
+See <a
+href="http://ltt.polymtl.ca/packages/markers-userspace-0.5.tar.bz2">markers-userspace-0.5.tar.bz2</a> or more recent.
-***********************************************************
-** Section 5 * Creating Debian or RPM packages **
-***********************************************************
+<p>
+Note that a new design document for a 3rd generation of tracepoint/marker-based
+userspace tracing is available at <a
+href="http://ltt.polymtl.ca/svn/trunk/lttv/doc/developer/ust.html">LTTng User-space Tracing
+Design</a>. This new infrastructure is not yet implemented.
-* Create custom LTTV Debian packages
+<p>
+The easy quick-and-dirty way to perform userspace tracing is currently to write
+an string to /mnt/debugfs/ltt/write_event. See <a
+href="#userspacetracing">Userspace tracing</a> in the
+installation for sources section of this document.
-Use : dpkg-buildpackage -rfakeroot
+<hr />
-You should then have your LTTV .deb files created for your architecture.
+<h2><a href="#TOCsection4" name="section4">Creating Debian or RPM packages</a></h2>
+<p>
-* Create custom LTTng packages
+<h3><a href="#TOCpkgdebian" name="pkgdebian">Create custom LTTV Debian packages</a></h3>
-For building LTTng Debian packages :
+<PRE>
+Use : dpkg-buildpackage -rfakeroot
+</PRE>
+<p>
+You should then have your LTTV .deb files created for your architecture.
-Get the build tree with patches applies as explained in section 2.
+<h3><a href="#TOCpkglttng" name="pkglttng">Create custom LTTng packages</a></h3>
+<p>
+For building LTTng Debian packages :
+get the build tree with patches applies as explained in section 2.
+<PRE>
make menuconfig (or xconfig or config) (customize your configuration)
make-kpkg kernel_image
-
+</PRE>
+<p>
You will then see your freshly created .deb in /usr/src. Install it with
+<PRE>
dpkg -i /usr/src/(image-name).deb
-
+</PRE>
+<p>
Then, follow the section "Editing the system wide configuration" in section 2.
+<hr />
+<h2><a href="#TOCsection5" name="section5">Examples of LTTng use in the field</a></h2>
+<p>
+A few examples of successful LTTng users :
+<ul>
+<li> Google are deploying LTTng on their servers. They want to use it to
+ monitor their production servers (with flight recorder mode tracing)
+ and to help them solve hard to reproduce problems. They have had
+ success with such tracing approach to fix "rare disk delay" issues and
+ VM-related issues presented in this article :
+<ul>
+ <li> <a href="http://ltt.polymtl.ca/papers/bligh-Reprint.pdf">Linux Kernel
+Debugging on Google-sized clusters at Ottawa Linux
+ Symposium 2007</a>
+</ul>
+<li> IBM Research have had problems with Commercial Scale-out applications,
+ which are being an increasing trend to split large server workloads.
+ They used LTTng successfully to solve a distributed filesystem-related
+ issue. It's presented in the same paper above.
+
+<li> Autodesk, in the development of their next-generation of Linux
+ audio/video edition applications, used LTTng extensively to solve
+ soft real-time issues they had. Also presented in the same paper.
+
+<li> Wind River included LTTng in their Linux distribution so their
+ clients, already familiar to Wind River own tracing solution in
+ VxWorks, car have the same kind of feature they have relied on for a
+ long time.
+
+<li> Montavista have integrated LTTng in their distribution for the same
+ reasons. It's used by Sony amongst others.
+
+<li> SuSE are currently integrating LTTng in their next SLES distribution,
+ because their clients asking for solutions which supports a kernel
+ closer to real-time need such tools to debug their problems.
+
+<li> A project between Ericsson, the Canadian Defense, NSERC and various
+ universities is just starting. It aims at monitoring and debugging
+ multi-core systems and provide automated and help user system behavior
+ analysis.
+
+<li> Siemens have been using LTTng internally for quite some time now.
+</ul>
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