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>
85 The lttng patch is necessary to have the tracing hooks in the kernel.
89 <h3><a href=
"#TOCarch" name=
"arch">Supported architectures
</a></h3>
94 <li> PowerPC
32 and
64 bits
95 <li> ARM (with limited timestamping precision, e.g.
1HZ. Need
96 architecture-specific support for better precision)
98 <li> sh (partial architecture-specific instrumentation)
99 <li> sparc64 (partial architecture-specific instrumentation)
100 <li> s390 (partial architecture-specific instrumentation)
101 <li> Other architectures supported without architecture-specific instrumentation
102 and with low-resolution timestamps.
<br>
107 <li> Intel
32/
64 bits
108 <li> PowerPC
32 and
64 bits
109 <li> Possibly others. Takes care of endianness and type size difference between
110 the LTTng traces and the LTTV analysis tool.
115 <h2><a href=
"#TOCsection1" name=
"section1">Installation from sources
</a></h2>
118 <h3><a href=
"#TOCprerequisites" name=
"prerequisites">Prerequisites
</a></h3>
121 Tools needed to follow the package download steps :
129 You have to install the standard development libraries and programs necessary
130 to compile a kernel :
133 (from Documentation/Changes in the Linux kernel tree)
134 Gnu C
2.95.3 # gcc --version
135 Gnu make
3.79.1 # make --version
136 binutils
2.12 # ld -v
137 util-linux
2.10o # fdformat --version
138 module-init-tools
0.9.10 # depmod -V
142 You might also want to have libncurses5 to have the text mode kernel
143 configuration menu, but there are alternatives.
146 Prerequisites for LTTV
0.x.x installation are :
150 gtk
2.4 or better development libraries
151 (Debian : libgtk2.0, libgtk2.0-dev)
152 (Fedora : gtk2, gtk2-devel)
153 note : For Fedora users : this might require at least core
3 from Fedora,
154 or you might have to compile your own GTK2 library.
155 glib
2.4 or better development libraries
156 (Debian : libglib2.0-
0, libglib2.0-dev)
157 (Fedora : glib2, glib2-devel)
158 libpopt development libraries
159 (Debian : libpopt0, libpopt-dev)
161 libpango development libraries
162 (Debian : libpango1.0, libpango1.0-dev)
163 (Fedora : pango, pango-devel)
164 libc6 development librairies
165 (Debian : libc6, libc6-dev)
166 (Fedora : glibc, glibc)
173 See the list of compatibilities between LTTng, ltt-control and LTTV at :
175 href=
"http://ltt.polymtl.ca/svn/trunk/lttv/doc/developer/lttng-lttv-compatibility.html">LTTng+LTTV
176 versions compatibility
</a>.
179 <h3><a href=
"#TOCgetlttng" name=
"getlttng">Getting the LTTng packages
</a></h3>
185 (see http://ltt.polymtl.ca/lttng for package listing)
186 wget http://ltt.polymtl.ca/lttng/patch-
2.6.X-lttng-
0.x.xx.tar.bz2
187 bzip2 -cd patch-
2.6.X-lttng-
0.x.xx.tar.bz2 | tar xvof -
191 <h3><a href=
"#TOCgetlttngsrc" name=
"getlttngsrc">Getting LTTng kernel sources
</a></h3>
196 wget http://kernel.org/pub/linux/kernel/v2.6/linux-
2.6.X.tar.bz2
197 bzip2 -cd linux-
2.6.X.tar.bz2 | tar xvof -
199 - For LTTng
0.9.4- cat /usr/src/lttng/patch*-
2.6.X-lttng-
0.x.xx* | patch -p1
200 - For LTTng
0.9.5+ apply the patches in the order specified in the series file,
203 mv linux-
2.6.X linux-
2.6.X-lttng-
0.x.xx
207 <h3><a href=
"#TOCinstalllttng" name=
"installlttng">Installing a LTTng kernel
</a></h3>
211 cd /usr/src/linux-
2.6.X-lttng-
0.x.xx
212 make menuconfig (or make xconfig or make config)
213 Select the < Help
> button if you are not familiar with kernel
215 Items preceded by [*] means they has to be built into the kernel.
216 Items preceded by [M] means they has to be built as modules.
217 Items preceded by [ ] means they should be removed.
218 go to the
"General setup" section
219 Select the following options :
220 [*] Prompt for development and/or incomplete code/drivers
222 [*] Activate userspace markers ABI (experimental, optional)
223 [*] Immediate value optimization (optional)
224 [*] Linux Trace Toolkit Next Generation (LTTng) --->
225 <M> or <*
> Compile lttng tracing probes
226 <M> or <*
> Linux Trace Toolkit High-speed Lockless Data Relay
227 <M> or <*
> Linux Trace Toolkit Lock-Protected Data Relay
228 <M> or <*
> Linux Trace Toolkit Serializer
229 <M> or <*
> Linux Trace Toolkit Marker Control
230 <M> or <*
> Linux Trace Toolkit Tracer
231 [*] Align Linux Trace Toolkit Traces
232 <M> or <*
> Support logging events from userspace
233 [*] Support trace extraction from crash dump
234 <M> or <*
> Linux Trace Toolkit Trace Controller
235 <M> or <*
> Linux Trace Toolkit State Dump
241 (if necessary, create a initrd with mkinitrd or your preferate alternative)
242 (mkinitrd -o /boot/initrd.img-
2.6.X-lttng-
0.x.xx
2.6.X-lttng-
0.x.xx)
247 Select the Linux
2.6.X-lttng-
0.x.xx kernel in your boot loader.
250 cp vmlinux.strip /boot/vmlinux-
2.6.X-lttng-
0.x.xx
251 cp System.map /boot/System.map-
2.6.X-lttng-
0.x.xx
252 cp .config /boot/config-
2.6.X-lttng-
0.x.xx
253 depmod -ae -F /boot/System.map-
2.6.X-lttng-
0.x.xx
2.6.X-lttng-
0.x.xx
254 mkinitrd /boot/initrd.img-
2.6.X-lttng-
0.x.xx
2.6.X-lttng-
0.x.xx
255 (edit /etc/yaboot.conf to add a new entry pointing to your kernel : the entry
256 that comes first is the default kernel)
258 select the right entry at the yaboot prompt (see choices : tab, select : type
259 the kernel name followed by enter)
260 Select the Linux
2.6.X-lttng-
0.x.xx kernel in your boot loader.
264 <h3><a href=
"#TOCeditconfig" name=
"editconfig">Editing the system wide
265 configuration
</a></h3>
268 You must activate debugfs and specify a mount point. This is typically done in
269 fstab such that it happens at boot time. If you have never used DebugFS before,
270 these operation would do this for you :
274 cp /etc/fstab /etc/fstab.lttng.bkp
275 echo
"debugfs /mnt/debugfs debugfs rw 0 0" >> /etc/fstab
279 then, rebooting or issuing the following command will activate debugfs :
285 You need to load the LTT modules to be able to control tracing from user
286 space. This is done by issuing the following commands. Note however
287 these commands load all LTT modules. Depending on what options you chose to
288 compile statically, you may not need to issue all these commands.
291 modprobe ltt-trace-control
292 modprobe ltt-marker-control
294 modprobe ltt-serialize
297 modprobe kernel-trace
303 modprobe syscall-trace
305 #if locking tracing is wanted, uncomment the following
306 #modprobe lockdep-trace
310 If you want to have complete information about the kernel state (including all
311 the process names), you need to load the ltt-statedump module. This is done by
312 issuing the command :
315 modprobe ltt-statedump
318 You can automate at boot time loading the ltt-control module by :
321 cp /etc/modules /etc/modules.bkp
322 echo ltt-trace-control
>> /etc/modules
323 echo ltt-marker-control
>> /etc/modules
324 echo ltt-tracer
>> /etc/modules
325 echo ltt-serialize
>> /etc/modules
326 echo ltt-relay
>> /etc/modules
327 echo ipc-trace
>> /etc/modules
328 echo kernel-trace
>> /etc/modules
329 echo mm-trace
>> /etc/modules
330 echo net-trace
>> /etc/modules
331 echo fs-trace
>> /etc/modules
332 echo jbd2-trace
>> /etc/modules
333 echo ext4-trace
>> /etc/modules
334 echo syscall-trace
>> /etc/modules
335 echo trap-trace
>> /etc/modules
336 #if locking tracing is wanted, uncomment the following
337 #echo lockdep-trace
>> /etc/modules
341 <h3><a href=
"#TOCgetlttctl" name=
"getlttctl">Getting and installing the
342 ltt-control package (on the traced machine)
</a></h3>
344 (note : the ltt-control package contains lttd and lttctl. Although it has the
345 same name as the ltt-control kernel module, they are *not* the same thing.)
350 wget http://ltt.polymtl.ca/lttng/ltt-control-
0.x-xxxx2006.tar.gz
351 gzip -cd ltt-control-
0.x-xxxx2008.tar.gz | tar xvof -
352 cd ltt-control-
0.x-xxxx2006
353 (refer to README to see the development libraries that must be installed on you
360 <h3><a href=
"#TOCuserspacetracing" name=
"userspacetracing">Userspace tracing
</a></h3>
363 Make sure you selected the kernel menuconfig option :
364 <M> or <*
> Support logging events from userspace
365 And that the ltt-userspace-event kernel module is loaded if selected as a
368 Simple userspace tracing is available through
369 echo
"some text to record" > /mnt/debugfs/ltt/write_event
371 It will appear in the trace under event :
376 <h3><a href=
"#TOCgetlttv" name=
"getlttv">Getting and installing the LTTV package
377 (on the visualisation machine, same
378 or different from the visualisation machine)
</a></h3>
383 wget http://ltt.polymtl.ca/packages/lttv-
0.x.xx-xxxx2008.tar.gz
384 gzip -cd lttv-
0.x.xx-xxxx2008.tar.gz | tar xvof -
385 cd lttv-
0.x.xx-xxxx2008
386 (refer to README to see the development libraries that must be installed on your
396 <h2><a href=
"#TOCsection2" name=
"section2">Using LTTng and LTTV
</a></h2>
398 <li><b>IMPORTANT : Arm Linux Kernel Markers after each boot before tracing
</b></li>
403 <h3><a href=
"#TOCuselttvgui" name=
"uselttvgui">Use graphical LTTV to control
404 tracing and analyse traces
</a></h3>
406 lttv-gui (or /usr/local/bin/lttv-gui)
407 - Spot the
"Tracing Control" icon : click on it
408 (it's a traffic light icon)
409 - enter the root password
413 * You should now see a trace
416 <h3><a href=
"#TOCuselttngtext" name=
"uselttngtext">Use text mode LTTng to control tracing
</a></h3>
418 The tracing can be controlled from a terminal by using the lttctl command (as
423 lttctl -C -w /tmp/trace1 trace1
425 Stop tracing and destroy trace channels :
429 see lttctl --help for details.
432 (note : to see if the buffers has been filled, look at the dmesg output after
433 lttctl -R or after stopping tracing from the GUI, it will show an event lost
434 count. If it is the case, try using larger buffers. See lttctl --help to learn
435 how. lttv now also shows event lost messages in the console when loading a trace
436 with missing events or lost subbuffers.)
438 <h3><a href=
"#TOCuselttvtext" name=
"uselttvtext">Use text mode LTTV
</a></h3>
440 Feel free to look in /usr/local/lib/lttv/plugins to see all the text and
441 graphical plugins available.
443 For example, a simple trace dump in text format is available with :
445 lttv -m textDump -t /tmp/trace
448 See lttv -m textDump --help for detailed command line options of textDump.
450 It is, in the current state of the project, very useful to use
"grep" on the
451 text output to filter by specific event fields. You can later copy the timestamp
452 of the events to the clipboard and paste them in the GUI by clicking on the
453 bottom right label
"Current time". Support for this type of filtering should
454 be added to the filter module soon.
456 <h3><a href=
"#TOChybrid" name=
"hybrid">Tracing in
"Hybrid" mode
</a></h3>
458 Starting from LTTng
0.5.105 and ltt-control
0.20, a new mode can be used :
459 hybrid. It can be especially useful when studying big workloads on a long period
462 When using this mode, the most important, low rate control information will be
463 recorded during all the trace by lttd (i.e. process creation/exit). The high
464 rate information (i.e. interrupt/traps/syscall entry/exit) will be kept in a
465 flight recorder buffer (now named flight-channelname_X).
467 The following lttctl commands take an hybrid trace :
469 Create trace channel, start lttd on normal channels, start tracing:
471 lttctl -C -w /tmp/trace2 -o channel.kernel.overwrite=
1 trace2
474 Stop tracing, start lttd on flight recorder channels, destroy trace channels :
476 lttctl -D -w /tmp/trace2 trace2
479 Each
"overwrite" channel is flight recorder channel.
482 <h3><a href=
"#TOCflight" name=
"flight">Tracing in flight recorder mode
</a></h3>
483 <li>Flight recorder mode
</li>
485 The flight recorder mode writes data into overwritten buffers for all channels,
486 including control channels, except for the facilities tracefiles. It consists of
487 setting all channels to
"overwrite".
489 The following lttctl commands take a flight recorder trace :
491 lttctl -C -w /tmp/trace3 -o channel.all.overwrite=
1 trace3
493 lttctl -D -w /tmp/trace3 trace3
499 <h2><a href=
"#TOCsection3" name=
"section3">Adding new instrumentations with the
503 <h3><a href=
"#TOCkerneltp" name=
"kerneltp">Adding kernel
504 instrumentation
</a></h3>
508 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>
510 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
514 href=
"http://git.kernel.org/?p=linux/kernel/git/compudj/linux-2.6-lttng.git;a=tree;f=ltt/probes">ltt/probes/
</a>
515 for LTTng probe examples.
517 <h3><a href=
"#TOCusertp" name=
"usertp">Adding userspace instrumentation
</a></h3>
519 Add new events to userspace programs with
520 <a href=
"http://ltt.polymtl.ca/packages/">userspace markers packages
</a>.
521 Get the latest markers-userspace-*.tar.bz2 and see the Makefile and examples. It
522 allows inserting markers in executables and libraries, currently only on x86_32
525 href=
"http://ltt.polymtl.ca/packages/markers-userspace-0.5.tar.bz2">markers-userspace-
0.5.tar.bz2
</a> or more recent.
528 Note that a new design document for a
3rd generation of tracepoint/marker-based
529 userspace tracing is available at
<a
530 href=
"http://ltt.polymtl.ca/svn/trunk/lttv/doc/developer/ust.html">LTTng User-space Tracing
531 Design
</a>. This new infrastructure is not yet implemented.
534 The easy quick-and-dirty way to perform userspace tracing is currently to write
535 an string to /mnt/debugfs/ltt/write_event. See
<a
536 href=
"#userspacetracing">Userspace tracing
</a> in the
537 installation for sources section of this document.
541 <h2><a href=
"#TOCsection4" name=
"section4">Creating Debian or RPM packages
</a></h2>
544 <h3><a href=
"#TOCpkgdebian" name=
"pkgdebian">Create custom LTTV Debian packages
</a></h3>
547 Use : dpkg-buildpackage -rfakeroot
550 You should then have your LTTV .deb files created for your architecture.
552 <h3><a href=
"#TOCpkglttng" name=
"pkglttng">Create custom LTTng packages
</a></h3>
554 For building LTTng Debian packages :
555 get the build tree with patches applies as explained in section
2.
558 make menuconfig (or xconfig or config) (customize your configuration)
559 make-kpkg kernel_image
562 You will then see your freshly created .deb in /usr/src. Install it with
564 dpkg -i /usr/src/(image-name).deb
567 Then, follow the section
"Editing the system wide configuration" in section
2.
571 <h2><a href=
"#TOCsection5" name=
"section5">Examples of LTTng use in the field
</a></h2>
573 A few examples of successful LTTng users :
576 <li> Google are deploying LTTng on their servers. They want to use it to
577 monitor their production servers (with flight recorder mode tracing)
578 and to help them solve hard to reproduce problems. They have had
579 success with such tracing approach to fix
"rare disk delay" issues and
580 VM-related issues presented in this article :
582 <li> <a href=
"http://ltt.polymtl.ca/papers/bligh-Reprint.pdf">Linux Kernel
583 Debugging on Google-sized clusters at Ottawa Linux
586 <li> IBM Research have had problems with Commercial Scale-out applications,
587 which are being an increasing trend to split large server workloads.
588 They used LTTng successfully to solve a distributed filesystem-related
589 issue. It's presented in the same paper above.
591 <li> Autodesk, in the development of their next-generation of Linux
592 audio/video edition applications, used LTTng extensively to solve
593 soft real-time issues they had. Also presented in the same paper.
595 <li> Wind River included LTTng in their Linux distribution so their
596 clients, already familiar to Wind River own tracing solution in
597 VxWorks, car have the same kind of feature they have relied on for a
600 <li> Montavista have integrated LTTng in their distribution for the same
601 reasons. It's used by Sony amongst others.
603 <li> SuSE are currently integrating LTTng in their next SLES distribution,
604 because their clients asking for solutions which supports a kernel
605 closer to real-time need such tools to debug their problems.
607 <li> A project between Ericsson, the Canadian Defense, NSERC and various
608 universities is just starting. It aims at monitoring and debugging
609 multi-core systems and provide automated and help user system behavior
612 <li> Siemens have been using LTTng internally for quite some time now.