1 <!DOCTYPE html PUBLIC
"-//W3C//DTD HTML 4.01 Transitional//EN">
4 <title>Linux Trace Toolkit Next Generation User Documentation
</title>
8 <h1>Linux Trace Toolkit Next Generation User Documentation
</h1>
10 Author : Mathieu Desnoyers, September
2005<br>
11 Last update : January
21st,
2009<br>
12 (originally known as the LTTng QUICKSTART guide)
14 <h2>Table of Contents
</h2>
17 <li><a href=
"#intro" name=
"TOCintro">Introduction
</a></li>
19 <li><a href=
"#arch" name=
"TOCarch">Supported architectures
</a></li>
22 <li><a href=
"#section1" name=
"TOCsection1">Installing LTTng and LTTV from
25 <li><a href=
"#prerequisites" name=
"TOCprerequisites">Prerequisistes
</li>
26 <li><a href=
"#getlttng" name=
"TOCgetlttng">Getting the LTTng packages
</li>
27 <li><a href=
"#getlttngsrc" name=
"TOCgetlttngsrc">Getting the LTTng kernel sources
</li>
28 <li><a href=
"#installlttng" name=
"TOCinstalllttng">Installing a LTTng kernel
</li>
29 <li><a href=
"#editconfig" name=
"TOCeditconfig">Editing the system wide
31 <li><a href=
"#getlttctl" name=
"TOCgetlttctl">Getting and installing the
32 ltt-control package
</li>
33 <li><a href=
"#userspacetracing" name=
"TOCuserspacetracing">Userspace Tracing
</li>
34 <li><a href=
"#getlttv" name=
"TOCgetlttv">Getting and installing the LTTV package
</ul>
36 <li><a href=
"#section2" name=
"TOCsection2">Using LTTng and LTTV
</a></li>
38 <li><a href=
"#uselttvgui" name=
"TOCuselttvgui">Use graphical LTTV to control
39 tracing and analyse traces
</a></li>
40 <li><a href=
"#uselttngtext" name=
"TOCuselttngtext">Use text mode LTTng to
41 control tracing
</a></li>
42 <li><a href=
"#uselttvtext" name=
"TOCuselttvtext">Use text mode LTTV
</a></li>
43 <li><a href=
"#hybrid" name=
"TOChybrid">Tracing in
"Hybrid" mode
</a></li>
44 <li><a href=
"#flight" name=
"TOCflight">Tracing in flight recorder mode
</a></li>
47 <li><a href=
"#section3" name=
"TOCsection3">Adding kernel and user-space
50 <li><a href=
"#kerneltp" name=
"TOCkerneltp">Adding kernel instrumentation
</a></li>
51 <li><a href=
"#usertp" name=
"TOCusertp">Adding userspace instrumentation
</a></li>
54 <li><a href=
"#section4" name=
"TOCsection4">Creating Debian and RPM packages
57 <li><a href=
"#pkgdebian" name=
"TOCpkgdebian">Create custom LTTV Debian
58 <li><a href=
"#pkglttng" name=
"TOCpkglttng">Create custom LTTng packages
</a></li>
61 <li><a href=
"#section5" name=
"TOCsection5">Examples of LTTng use in the
68 <h2><a href=
"#TOCintro" name=
"intro">Introduction
</a></h2>
70 This document is made of five parts : the first one explains how
71 to install LTTng and LTTV from sources, the second one describes the steps
72 to follow to trace a system and view it. The third part explains
73 briefly how to add a new trace point to the kernel and to user space
74 applications. The fourth part explains how to create Debian or RPM
75 packages from the LTTng and LTTV sources. The fifth and last part describes use
76 of LTTng in the field.
78 These operations are made for installing the LTTng
0.86 tracer on a linux
2.6.X
79 kernel. You will also find instructions for installation of LTTV
0.12.x : the
80 Linux Trace Toolkit Viewer.
81 To see the list of compatibilities between LTTng, ltt-control, LTTV, please
84 href=
"http://ltt.polymtl.ca/svn/trunk/lttv/doc/developer/lttng-lttv-compatibility.html">LTTng+LTTV versions compatibility
</a>
86 The ongoing work had the Linux Kernel Markers integrated in the mainline Linux
87 kernel since Linux
2.6.24 and the Tracepoints since
2.6.28. In its current
88 state, the lttng patchset is necessary to have the trace clocksource, the
89 instrumentation and the LTTng high-speed data extraction mechanism added to the
94 <h3><a href=
"#TOCarch" name=
"arch">Supported architectures
</a></h3>
99 <li> PowerPC
32 and
64 bits
100 <li> ARM (with limited timestamping precision, e.g.
1HZ. Need
101 architecture-specific support for better precision)
103 <li> sh (partial architecture-specific instrumentation)
104 <li> sparc64 (partial architecture-specific instrumentation)
105 <li> s390 (partial architecture-specific instrumentation)
106 <li> Other architectures supported without architecture-specific instrumentation
107 and with low-resolution timestamps.
<br>
112 <li> Intel
32/
64 bits
113 <li> PowerPC
32 and
64 bits
114 <li> Possibly others. Takes care of endianness and type size difference between
115 the LTTng traces and the LTTV analysis tool.
120 <h2><a href=
"#TOCsection1" name=
"section1">Installation from sources
</a></h2>
123 <h3><a href=
"#TOCprerequisites" name=
"prerequisites">Prerequisites
</a></h3>
126 Tools needed to follow the package download steps :
134 You have to install the standard development libraries and programs necessary
135 to compile a kernel :
138 (from Documentation/Changes in the Linux kernel tree)
139 Gnu C
2.95.3 # gcc --version
140 Gnu make
3.79.1 # make --version
141 binutils
2.12 # ld -v
142 util-linux
2.10o # fdformat --version
143 module-init-tools
0.9.10 # depmod -V
147 You might also want to have libncurses5 to have the text mode kernel
148 configuration menu, but there are alternatives.
151 Prerequisites for LTTV
0.x.x installation are :
155 gtk
2.4 or better development libraries
156 (Debian : libgtk2.0, libgtk2.0-dev)
157 (Fedora : gtk2, gtk2-devel)
158 note : For Fedora users : this might require at least core
3 from Fedora,
159 or you might have to compile your own GTK2 library.
160 glib
2.4 or better development libraries
161 (Debian : libglib2.0-
0, libglib2.0-dev)
162 (Fedora : glib2, glib2-devel)
163 libpopt development libraries
164 (Debian : libpopt0, libpopt-dev)
166 libpango development libraries
167 (Debian : libpango1.0, libpango1.0-dev)
168 (Fedora : pango, pango-devel)
169 libc6 development librairies
170 (Debian : libc6, libc6-dev)
171 (Fedora : glibc, glibc)
178 See the list of compatibilities between LTTng, ltt-control and LTTV at :
180 href=
"http://ltt.polymtl.ca/svn/trunk/lttv/doc/developer/lttng-lttv-compatibility.html">LTTng+LTTV
181 versions compatibility
</a>.
184 <h3><a href=
"#TOCgetlttng" name=
"getlttng">Getting the LTTng packages
</a></h3>
190 (see http://ltt.polymtl.ca/lttng for package listing)
191 wget http://ltt.polymtl.ca/lttng/patch-
2.6.X-lttng-
0.x.xx.tar.bz2
192 bzip2 -cd patch-
2.6.X-lttng-
0.x.xx.tar.bz2 | tar xvof -
196 <h3><a href=
"#TOCgetlttngsrc" name=
"getlttngsrc">Getting LTTng kernel sources
</a></h3>
201 wget http://kernel.org/pub/linux/kernel/v2.6/linux-
2.6.X.tar.bz2
202 bzip2 -cd linux-
2.6.X.tar.bz2 | tar xvof -
204 - For LTTng
0.9.4- cat /usr/src/lttng/patch*-
2.6.X-lttng-
0.x.xx* | patch -p1
205 - For LTTng
0.9.5+ apply the patches in the order specified in the series file,
208 mv linux-
2.6.X linux-
2.6.X-lttng-
0.x.xx
212 <h3><a href=
"#TOCinstalllttng" name=
"installlttng">Installing a LTTng kernel
</a></h3>
216 cd /usr/src/linux-
2.6.X-lttng-
0.x.xx
217 make menuconfig (or make xconfig or make config)
218 Select the < Help
> button if you are not familiar with kernel
220 Items preceded by [*] means they has to be built into the kernel.
221 Items preceded by [M] means they has to be built as modules.
222 Items preceded by [ ] means they should be removed.
223 go to the
"General setup" section
224 Select the following options :
225 [*] Prompt for development and/or incomplete code/drivers
227 [*] Activate userspace markers ABI (experimental, optional)
228 [*] Immediate value optimization (optional)
229 [*] Linux Trace Toolkit Next Generation (LTTng) --->
230 <M> or <*
> Compile lttng tracing probes
231 <M> or <*
> Linux Trace Toolkit High-speed Lockless Data Relay
232 <M> or <*
> Linux Trace Toolkit Lock-Protected Data Relay
233 <M> or <*
> Linux Trace Toolkit Serializer
234 <M> or <*
> Linux Trace Toolkit Marker Control
235 <M> or <*
> Linux Trace Toolkit Tracer
236 [*] Align Linux Trace Toolkit Traces
237 <M> or <*
> Support logging events from userspace
238 [*] Support trace extraction from crash dump
239 <M> or <*
> Linux Trace Toolkit Trace Controller
240 <M> or <*
> Linux Trace Toolkit State Dump
246 (if necessary, create a initrd with mkinitrd or your preferate alternative)
247 (mkinitrd -o /boot/initrd.img-
2.6.X-lttng-
0.x.xx
2.6.X-lttng-
0.x.xx)
252 Select the Linux
2.6.X-lttng-
0.x.xx kernel in your boot loader.
255 cp vmlinux.strip /boot/vmlinux-
2.6.X-lttng-
0.x.xx
256 cp System.map /boot/System.map-
2.6.X-lttng-
0.x.xx
257 cp .config /boot/config-
2.6.X-lttng-
0.x.xx
258 depmod -ae -F /boot/System.map-
2.6.X-lttng-
0.x.xx
2.6.X-lttng-
0.x.xx
259 mkinitrd /boot/initrd.img-
2.6.X-lttng-
0.x.xx
2.6.X-lttng-
0.x.xx
260 (edit /etc/yaboot.conf to add a new entry pointing to your kernel : the entry
261 that comes first is the default kernel)
263 select the right entry at the yaboot prompt (see choices : tab, select : type
264 the kernel name followed by enter)
265 Select the Linux
2.6.X-lttng-
0.x.xx kernel in your boot loader.
269 <h3><a href=
"#TOCeditconfig" name=
"editconfig">Editing the system wide
270 configuration
</a></h3>
273 You must activate debugfs and specify a mount point. This is typically done in
274 fstab such that it happens at boot time. If you have never used DebugFS before,
275 these operation would do this for you :
279 cp /etc/fstab /etc/fstab.lttng.bkp
280 echo
"debugfs /mnt/debugfs debugfs rw 0 0" >> /etc/fstab
284 then, rebooting or issuing the following command will activate debugfs :
290 You need to load the LTT modules to be able to control tracing from user
291 space. This is done by issuing the following commands. Note however
292 these commands load all LTT modules. Depending on what options you chose to
293 compile statically, you may not need to issue all these commands.
296 modprobe ltt-trace-control
297 modprobe ltt-marker-control
299 modprobe ltt-serialize
302 modprobe kernel-trace
308 modprobe syscall-trace
310 #if locking tracing is wanted, uncomment the following
311 #modprobe lockdep-trace
315 If you want to have complete information about the kernel state (including all
316 the process names), you need to load the ltt-statedump module. This is done by
317 issuing the command :
320 modprobe ltt-statedump
323 You can automate at boot time loading the ltt-control module by :
326 cp /etc/modules /etc/modules.bkp
327 echo ltt-trace-control
>> /etc/modules
328 echo ltt-marker-control
>> /etc/modules
329 echo ltt-tracer
>> /etc/modules
330 echo ltt-serialize
>> /etc/modules
331 echo ltt-relay
>> /etc/modules
332 echo ipc-trace
>> /etc/modules
333 echo kernel-trace
>> /etc/modules
334 echo mm-trace
>> /etc/modules
335 echo net-trace
>> /etc/modules
336 echo fs-trace
>> /etc/modules
337 echo jbd2-trace
>> /etc/modules
338 echo ext4-trace
>> /etc/modules
339 echo syscall-trace
>> /etc/modules
340 echo trap-trace
>> /etc/modules
341 #if locking tracing is wanted, uncomment the following
342 #echo lockdep-trace
>> /etc/modules
346 <h3><a href=
"#TOCgetlttctl" name=
"getlttctl">Getting and installing the
347 ltt-control package (on the traced machine)
</a></h3>
349 (note : the ltt-control package contains lttd and lttctl. Although it has the
350 same name as the ltt-control kernel module, they are *not* the same thing.)
355 wget http://ltt.polymtl.ca/lttng/ltt-control-
0.x-xxxx2006.tar.gz
356 gzip -cd ltt-control-
0.x-xxxx2008.tar.gz | tar xvof -
357 cd ltt-control-
0.x-xxxx2006
358 (refer to README to see the development libraries that must be installed on you
365 <h3><a href=
"#TOCuserspacetracing" name=
"userspacetracing">Userspace tracing
</a></h3>
368 Make sure you selected the kernel menuconfig option :
369 <M> or <*
> Support logging events from userspace
370 And that the ltt-userspace-event kernel module is loaded if selected as a
373 Simple userspace tracing is available through
374 echo
"some text to record" > /mnt/debugfs/ltt/write_event
376 It will appear in the trace under event :
381 <h3><a href=
"#TOCgetlttv" name=
"getlttv">Getting and installing the LTTV package
382 (on the visualisation machine, same
383 or different from the visualisation machine)
</a></h3>
388 wget http://ltt.polymtl.ca/packages/lttv-
0.x.xx-xxxx2008.tar.gz
389 gzip -cd lttv-
0.x.xx-xxxx2008.tar.gz | tar xvof -
390 cd lttv-
0.x.xx-xxxx2008
391 (refer to README to see the development libraries that must be installed on your
401 <h2><a href=
"#TOCsection2" name=
"section2">Using LTTng and LTTV
</a></h2>
403 <li><b>IMPORTANT : Arm Linux Kernel Markers after each boot before tracing
</b></li>
408 <h3><a href=
"#TOCuselttvgui" name=
"uselttvgui">Use graphical LTTV to control
409 tracing and analyse traces
</a></h3>
411 lttv-gui (or /usr/local/bin/lttv-gui)
412 - Spot the
"Tracing Control" icon : click on it
413 (it's a traffic light icon)
414 - enter the root password
418 * You should now see a trace
421 <h3><a href=
"#TOCuselttngtext" name=
"uselttngtext">Use text mode LTTng to control tracing
</a></h3>
423 The tracing can be controlled from a terminal by using the lttctl command (as
428 lttctl -C -w /tmp/trace1 trace1
430 Stop tracing and destroy trace channels :
434 see lttctl --help for details.
437 (note : to see if the buffers has been filled, look at the dmesg output after
438 lttctl -D or after stopping tracing from the GUI, it will show an event lost
439 count. If it is the case, try using larger buffers. See lttctl --help to learn
440 how. lttv now also shows event lost messages in the console when loading a trace
441 with missing events or lost subbuffers.)
443 <h3><a href=
"#TOCuselttvtext" name=
"uselttvtext">Use text mode LTTV
</a></h3>
445 Feel free to look in /usr/local/lib/lttv/plugins to see all the text and
446 graphical plugins available.
448 For example, a simple trace dump in text format is available with :
450 lttv -m textDump -t /tmp/trace
453 See lttv -m textDump --help for detailed command line options of textDump.
455 It is, in the current state of the project, very useful to use
"grep" on the
456 text output to filter by specific event fields. You can later copy the timestamp
457 of the events to the clipboard and paste them in the GUI by clicking on the
458 bottom right label
"Current time". Support for this type of filtering should
459 be added to the filter module soon.
461 <h3><a href=
"#TOChybrid" name=
"hybrid">Tracing in
"Hybrid" mode
</a></h3>
463 Starting from LTTng
0.5.105 and ltt-control
0.20, a new mode can be used :
464 hybrid. It can be especially useful when studying big workloads on a long period
467 When using this mode, the most important, low rate control information will be
468 recorded during all the trace by lttd (i.e. process creation/exit). The high
469 rate information (i.e. interrupt/traps/syscall entry/exit) will be kept in a
470 flight recorder buffer (now named flight-channelname_X).
472 The following lttctl commands take an hybrid trace :
474 Create trace channel, start lttd on normal channels, start tracing:
476 lttctl -C -w /tmp/trace2 -o channel.kernel.overwrite=
1 trace2
479 Stop tracing, start lttd on flight recorder channels, destroy trace channels :
481 lttctl -D -w /tmp/trace2 trace2
484 Each
"overwrite" channel is flight recorder channel.
487 <h3><a href=
"#TOCflight" name=
"flight">Tracing in flight recorder mode
</a></h3>
488 <li>Flight recorder mode
</li>
490 The flight recorder mode writes data into overwritten buffers for all channels,
491 including control channels, except for the facilities tracefiles. It consists of
492 setting all channels to
"overwrite".
494 The following lttctl commands take a flight recorder trace :
496 lttctl -C -w /tmp/trace3 -o channel.all.overwrite=
1 trace3
498 lttctl -D -w /tmp/trace3 trace3
504 <h2><a href=
"#TOCsection3" name=
"section3">Adding new instrumentations with the
508 <h3><a href=
"#TOCkerneltp" name=
"kerneltp">Adding kernel
509 instrumentation
</a></h3>
513 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>
515 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
519 href=
"http://git.kernel.org/?p=linux/kernel/git/compudj/linux-2.6-lttng.git;a=tree;f=ltt/probes">ltt/probes/
</a>
520 for LTTng probe examples.
522 <h3><a href=
"#TOCusertp" name=
"usertp">Adding userspace instrumentation
</a></h3>
524 Add new events to userspace programs with
525 <a href=
"http://ltt.polymtl.ca/packages/">userspace markers packages
</a>.
526 Get the latest markers-userspace-*.tar.bz2 and see the Makefile and examples. It
527 allows inserting markers in executables and libraries, currently only on x86_32
530 href=
"http://ltt.polymtl.ca/packages/markers-userspace-0.5.tar.bz2">markers-userspace-
0.5.tar.bz2
</a> or more recent.
533 Note that a new design document for a
3rd generation of tracepoint/marker-based
534 userspace tracing is available at
<a
535 href=
"http://ltt.polymtl.ca/svn/trunk/lttv/doc/developer/ust.html">LTTng User-space Tracing
536 Design
</a>. This new infrastructure is not yet implemented.
539 The easy quick-and-dirty way to perform userspace tracing is currently to write
540 an string to /mnt/debugfs/ltt/write_event. See
<a
541 href=
"#userspacetracing">Userspace tracing
</a> in the
542 installation for sources section of this document.
546 <h2><a href=
"#TOCsection4" name=
"section4">Creating Debian or RPM packages
</a></h2>
549 <h3><a href=
"#TOCpkgdebian" name=
"pkgdebian">Create custom LTTV Debian packages
</a></h3>
552 Use : dpkg-buildpackage -rfakeroot
555 You should then have your LTTV .deb files created for your architecture.
557 <h3><a href=
"#TOCpkglttng" name=
"pkglttng">Create custom LTTng packages
</a></h3>
559 For building LTTng Debian packages :
560 get the build tree with patches applies as explained in section
2.
563 make menuconfig (or xconfig or config) (customize your configuration)
564 make-kpkg kernel_image
567 You will then see your freshly created .deb in /usr/src. Install it with
569 dpkg -i /usr/src/(image-name).deb
572 Then, follow the section
"Editing the system wide configuration" in section
2.
576 <h2><a href=
"#TOCsection5" name=
"section5">Examples of LTTng use in the field
</a></h2>
578 A few examples of successful LTTng users :
581 <li> Google are deploying LTTng on their servers. They want to use it to
582 monitor their production servers (with flight recorder mode tracing)
583 and to help them solve hard to reproduce problems. They have had
584 success with such tracing approach to fix
"rare disk delay" issues and
585 VM-related issues presented in this article :
587 <li> <a href=
"http://ltt.polymtl.ca/papers/bligh-Reprint.pdf">Linux Kernel
588 Debugging on Google-sized clusters at Ottawa Linux
591 <li> IBM Research have had problems with Commercial Scale-out applications,
592 which are being an increasing trend to split large server workloads.
593 They used LTTng successfully to solve a distributed filesystem-related
594 issue. It's presented in the same paper above.
596 <li> Autodesk, in the development of their next-generation of Linux
597 audio/video edition applications, used LTTng extensively to solve
598 soft real-time issues they had. Also presented in the same paper.
600 <li> Wind River included LTTng in their Linux distribution so their
601 clients, already familiar to Wind River own tracing solution in
602 VxWorks, car have the same kind of feature they have relied on for a
605 <li> Montavista have integrated LTTng in their distribution for the same
606 reasons. It's used by Sony amongst others.
608 <li> SuSE are currently integrating LTTng in their next SLES distribution,
609 because their clients asking for solutions which supports a kernel
610 closer to real-time need such tools to debug their problems.
612 <li> A project between Ericsson, the Canadian Defense, NSERC and various
613 universities is just starting. It aims at monitoring and debugging
614 multi-core systems and provide automated and help user system behavior
617 <li> Siemens have been using LTTng internally for quite some time now.