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   4   <title>Linux Trace Toolkit Next Generation User Documentation</title>
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   7
   8 <h1>Linux Trace Toolkit Next Generation User Documentation</h1>
   9
  10 Author : Mathieu Desnoyers, September 2005<br>
  11 Last update : January 21st, 2009<br>
  12 (originally known as the LTTng QUICKSTART guide)
  13
  14 <h2>Table of Contents</h2>
  15 <ul>
  16
  17 <li><a href="#intro" name="TOCintro">Introduction</a></li>
  18 <li><a href="#section1" name="TOCsection1">Installing LTTng and LTTV from
  19 sources</a></li>
  20 <ul>
  21 <li><a href="#prerequisites" name="TOCprerequisites">Prerequisistes</ul>
  22 <li><a href="#getlttng" name="TOCgetlttng">Getting the LTTng packages</ul>
  23 <li><a href="#getlttngsrc" name="TOCgetlttngsrc">Getting the LTTng kernel sources</ul>
  24 <li><a href="#installlttng" name="TOCinstalllttng">Installing a LTTng kernel</ul>
  25 <li><a href="#editconfig" name="TOCeditconfig">Editing the system wide
  26 configuration</a>
  27 <li><a href="#getlttctl" name="TOCgetlttctl">Getting and installing the
  28 ltt-control package</ul>
  29 <li><a href="#userspacetracing" name="TOCuserspacetracing">Userspace Tracing</ul>
  30 <li><a href="#getlttv" name="TOCgetlttv">Getting and installing the LTTV package</ul>
  31 <li><a href="#section2" name="TOCsection2">Using LTTng and LTTV</a></li>
  32 <li><a href="#section3" name="TOCsection3">Adding kernel and user-space
  33 tracepoints</a></li>
  34 <li><a href="#section4" name="TOCsection4">Creating Debian and RPM packages
  35 from LTTV</a>
  36
  37 </ul>
  38
  39 <hr />
  40
  41 <h2><a href="#TOCintro" name="intro">Introduction</a></h2>
  42 <p>
  43 This document is made of four parts : the first one explains how
  44 to install LTTng and LTTV from sources, the second one describes the steps
  45 to follow to trace a system and view it. The third part explains
  46 briefly how to add a new trace point to the kernel and to user space
  47 applications. The fourth and last part explains how to create Debian or RPM
  48 packages from the LTTng and LTTV sources.
  49 <p>
  50 These operations are made for installing the LTTng 0.86 tracer on a linux 2.6.X
  51 kernel. You will also find instructions for installation of LTTV 0.12.x : the
  52 Linux Trace Toolkit Viewer.
  53 To see the list of compatibilities between LTTng, ltt-control, LTTV, please
  54 refer to :
  55 <a
  56 href="http://ltt.polymtl.ca/svn/trunk/lttv/doc/developer/lttng-lttv-compatibility.html">LTTng+LTTV versions compatibility</a>
  57 The lttng patch is necessary to have the tracing hooks in the kernel.
  58
  59 <br>
  60 <br>
  61 Supported architectures :
  62 br>
  63 LTTng :<br>
  64 <li> x86 32/64 bits
  65 <li> PowerPC 32 and 64 bits
  66 <li> ARM (with limited timestamping precision, e.g. 1HZ. Need
  67 architecture-specific support for better precision)
  68 <li> MIPS
  69 <br>
  70 <br>
  71 LTTV :<br>
  72 <li> Intel 32/64 bits
  73 <li> PowerPC 32 and 64 bits
  74 <li> Possibly others. Takes care of endianness and type size difference between
  75 the LTTng traces and the LTTV analysis tool.
  76
  77 <hr />
  78
  79
  80 <h2><a href="#TOCsection1" name="section1">Installation from sources</a></h2>
  81 <p>
  82
  83 <h3><a href="#TOCprerequisites" name="prerequisites">Prerequisites</a></h3>
  84 <ul>
  85 <p>
  86 Tools needed to follow the package download steps :
  87
  88 <li>wget
  89 <li>bzip2
  90 <li>gzip
  91 <li>tar
  92
  93 <p>
  94 You have to install the standard development libraries and programs necessary
  95 to compile a kernel :
  96
  97 <PRE>
  98 (from Documentation/Changes in the Linux kernel tree)
  99 Gnu C                2.95.3                # gcc --version
 100 Gnu make             3.79.1                # make --version
 101 binutils             2.12                  # ld -v
 102 util-linux           2.10o                 # fdformat --version
 103 module-init-tools    0.9.10                # depmod -V
 104 </PRE>
 105
 106 <p>
 107 You might also want to have libncurses5 to have the text mode kernel
 108 configuration menu, but there are alternatives.
 109
 110 <p>
 111 Prerequisites for LTTV 0.x.x installation are :
 112
 113 <PRE>
 114 gcc 3.2 or better
 115 gtk 2.4 or better development libraries
 116   (Debian : libgtk2.0, libgtk2.0-dev)
 117   (Fedora : gtk2, gtk2-devel)
 118   note : For Fedora users : this might require at least core 3 from Fedora,
 119   or you might have to compile your own GTK2 library.
 120 glib 2.4 or better development libraries
 121   (Debian : libglib2.0-0, libglib2.0-dev)
 122   (Fedora : glib2, glib2-devel)
 123 libpopt development libraries
 124   (Debian : libpopt0, libpopt-dev)
 125   (Fedora : popt)
 126 libpango development libraries
 127   (Debian : libpango1.0, libpango1.0-dev)
 128   (Fedora : pango, pango-devel)
 129 libc6 development librairies
 130   (Debian : libc6, libc6-dev)
 131   (Fedora : glibc, glibc)
 132 </PRE>
 133 </ul>
 134
 135 <li>Reminder</li>
 136
 137 <p>
 138 See the list of compatibilities between LTTng, ltt-control and LTTV at :
 139 <a
 140 href="http://ltt.polymtl.ca/svn/trunk/lttv/doc/developer/lttng-lttv-compatibility.html">LTTng+LTTV
 141 versions compatibility</a>.
 142
 143
 144 <h3><a href="#TOCgetlttng" name="getlttng">Getting the LTTng packages</a></h3>
 145
 146 <PRE>
 147 su -
 148 mkdir /usr/src/lttng
 149 cd /usr/src/lttng
 150 (see http://ltt.polymtl.ca/lttng for package listing)
 151 wget http://ltt.polymtl.ca/lttng/patch-2.6.X-lttng-0.x.xx.tar.bz2
 152 bzip2 -cd patch-2.6.X-lttng-0.x.xx.tar.bz2 | tar xvof -
 153 </PRE>
 154
 155
 156 <h3><a href="#TOCgetlttngsrc" name="getlttngsrc">Getting LTTng kernel sources</a></h3>
 157
 158 <PRE>
 159 su -
 160 cd /usr/src
 161 wget http://kernel.org/pub/linux/kernel/v2.6/linux-2.6.X.tar.bz2
 162 bzip2 -cd linux-2.6.X.tar.bz2 | tar xvof -
 163 cd linux-2.6.X
 164 - For LTTng 0.9.4- cat /usr/src/lttng/patch*-2.6.X-lttng-0.x.xx* | patch -p1
 165 - For LTTng 0.9.5+ apply the patches in the order specified in the series file,
 166   or use quilt
 167 cd ..
 168 mv linux-2.6.X linux-2.6.X-lttng-0.x.xx
 169 </PRE>
 170
 171
 172 <h3><a href="#TOCinstalllttng" name="installlttng">Installing a LTTng kernel</a></h3>
 173
 174 <PRE>
 175 su -
 176 cd /usr/src/linux-2.6.X-lttng-0.x.xx
 177 make menuconfig (or make xconfig or make config)
 178     Select the < Help > button if you are not familiar with kernel
 179     configuration.
 180     Items preceded by [*] means they has to be built into the kernel.
 181     Items preceded by [M] means they has to be built as modules.
 182     Items preceded by [ ] means they should be removed.
 183   go to the "General setup" section
 184     Select the following options :
 185     [*] Prompt for development and/or incomplete code/drivers
 186     [*] Activate markers
 187     [*] Activate userspace markers ABI (experimental, optional)
 188     [*] Immediate value optimization (optional)
 189     [*] Linux Trace Toolkit Next Generation (LTTng) --->
 190     <M> or <*> Compile lttng tracing probes
 191     <M> or <*> Linux Trace Toolkit High-speed Lockless Data Relay
 192     <M> or <*> Linux Trace Toolkit Lock-Protected Data Relay
 193     <M> or <*> Linux Trace Toolkit Serializer
 194     <M> or <*>   Linux Trace Toolkit Marker Control
 195     <M> or <*>     Linux Trace Toolkit Tracer
 196     [*] Align Linux Trace Toolkit Traces
 197     <M> or <*> Support logging events from userspace
 198     [*] Support trace extraction from crash dump
 199     <M> or <*> Linux Trace Toolkit Trace Controller
 200     <M> or <*> Linux Trace Toolkit State Dump
 201   Select <Exit>
 202   Select <Exit>
 203   Select <Yes>
 204 make
 205 make modules_install
 206 (if necessary, create a initrd with mkinitrd or your preferate alternative)
 207 (mkinitrd -o /boot/initrd.img-2.6.X-lttng-0.x.xx 2.6.X-lttng-0.x.xx)
 208
 209 -- on X86, X86_64
 210 make install
 211 reboot
 212 Select the Linux 2.6.X-lttng-0.x.xx kernel in your boot loader.
 213
 214 -- on PowerPC
 215 cp vmlinux.strip /boot/vmlinux-2.6.X-lttng-0.x.xx
 216 cp System.map /boot/System.map-2.6.X-lttng-0.x.xx
 217 cp .config /boot/config-2.6.X-lttng-0.x.xx
 218 depmod -ae -F /boot/System.map-2.6.X-lttng-0.x.xx 2.6.X-lttng-0.x.xx
 219 mkinitrd /boot/initrd.img-2.6.X-lttng-0.x.xx 2.6.X-lttng-0.x.xx
 220 (edit /etc/yaboot.conf to add a new entry pointing to your kernel : the entry
 221 that comes first is the default kernel)
 222 ybin
 223 select the right entry at the yaboot prompt (see choices : tab, select : type
 224 the kernel name followed by enter)
 225 Select the Linux 2.6.X-lttng-0.x.xx kernel in your boot loader.
 226 --
 227 </PRE>
 228
 229 <h3><a href="#TOCeditconfig" name="editconfig">Editing the system wide
 230 configuration</a></h3>
 231
 232 <p>
 233 You must activate debugfs and specify a mount point. This is typically done in
 234 fstab such that it happens at boot time.  If you have never used DebugFS before,
 235 these operation would do this for you :
 236
 237 <PRE>
 238 mkdir /mnt/debugfs
 239 cp /etc/fstab /etc/fstab.lttng.bkp
 240 echo "debugfs         /mnt/debugfs    debugfs rw              0       0"  >> /etc/fstab
 241 </PRE>
 242
 243 <p>
 244 then, rebooting or issuing the following command will activate debugfs :
 245 <PRE>
 246 mount /mnt/debugfs
 247 </PRE>
 248
 249 <p>
 250 You need to load the LTT modules to be able to control tracing from user
 251 space. This is done by issuing the following commands. Note however
 252 these commands load all LTT modules. Depending on what options you chose to
 253 compile statically, you may not need to issue all these commands.
 254
 255 <PRE>
 256 modprobe ltt-trace-control
 257 modprobe ltt-marker-control
 258 modprobe ltt-tracer
 259 modprobe ltt-serialize
 260 modprobe ltt-relay
 261 modprobe ipc-trace
 262 modprobe kernel-trace
 263 modprobe mm-trace
 264 modprobe net-trace
 265 modprobe fs-trace
 266 modprobe jbd2-trace
 267 modprobe ext4-trace
 268 modprobe syscall-trace
 269 modprobe trap-trace
 270 #if locking tracing is wanted, uncomment the following
 271 #modprobe lockdep-trace
 272 </PRE>
 273
 274 <p>
 275 If you want to have complete information about the kernel state (including all
 276 the process names), you need to load the ltt-statedump module. This is done by
 277 issuing the command :
 278
 279 <PRE>
 280 modprobe ltt-statedump
 281 </PRE>
 282 <p>
 283 You can automate at boot time loading the ltt-control module by :
 284
 285 <PRE>
 286 cp /etc/modules /etc/modules.bkp
 287 echo ltt-trace-control >> /etc/modules
 288 echo ltt-marker-control >> /etc/modules
 289 echo ltt-tracer >> /etc/modules
 290 echo ltt-serialize >> /etc/modules
 291 echo ltt-relay >> /etc/modules
 292 echo ipc-trace >> /etc/modules
 293 echo kernel-trace >> /etc/modules
 294 echo mm-trace >> /etc/modules
 295 echo net-trace >> /etc/modules
 296 echo fs-trace >> /etc/modules
 297 echo jbd2-trace >> /etc/modules
 298 echo ext4-trace >> /etc/modules
 299 echo syscall-trace >> /etc/modules
 300 echo trap-trace >> /etc/modules
 301 #if locking tracing is wanted, uncomment the following
 302 #echo lockdep-trace >> /etc/modules
 303 </PRE>
 304
 305
 306 <h3><a href="#TOCgetlttctl" name="getlttctl">Getting and installing the
 307 ltt-control package (on the traced machine)</a></h3>
 308 <p>
 309 (note : the ltt-control package contains lttd and lttctl. Although it has the
 310 same name as the ltt-control kernel module, they are *not* the same thing.)
 311
 312 <PRE>
 313 su -
 314 cd /usr/src
 315 wget http://ltt.polymtl.ca/lttng/ltt-control-0.x-xxxx2006.tar.gz
 316 gzip -cd ltt-control-0.x-xxxx2008.tar.gz | tar xvof -
 317 cd ltt-control-0.x-xxxx2006
 318 (refer to README to see the development libraries that must be installed on you
 319 system)
 320 ./configure
 321 make
 322 make install
 323 </PRE>
 324
 325 <h3><a href="#TOCuserspacetracing" name="userspacetracing">Userspace tracing</a></h3>
 326
 327 <PRE>
 328 Make sure you selected the kernel menuconfig option :
 329     <M> or <*> Support logging events from userspace
 330 And that the ltt-userspace-event kernel module is loaded if selected as a
 331 module.
 332
 333 Simple userspace tracing is available through
 334 echo "some text to record" > /mnt/debugfs/ltt/write_event
 335
 336 It will appear in the trace under event :
 337 channel : userspace
 338 event name : event
 339 </PRE>
 340
 341 <h3><a href="#TOCgetlttv" name="getlttv">Getting and installing the LTTV package
 342 (on the visualisation machine, same
 343 or different from the visualisation machine)</a></h3>
 344
 345 <PRE>
 346 su -
 347 cd /usr/src
 348 wget http://ltt.polymtl.ca/packages/lttv-0.x.xx-xxxx2008.tar.gz
 349 gzip -cd lttv-0.x.xx-xxxx2008.tar.gz | tar xvof -
 350 cd lttv-0.x.xx-xxxx2008
 351 (refer to README to see the development libraries that must be installed on your
 352 system)
 353 ./configure
 354 make
 355 make install
 356 </PRE>
 357
 358 <hr />
 359
 360
 361 <h2><a href="#TOCsection2" name="section2">Using LTTng and LTTV</a></h2>
 362
 363 <li>IMPORTANT : Arm Linux Kernel Markers after each boot</li>
 364 <PRE>
 365 ltt-armall
 366 </PRE>
 367
 368 <li>Use graphical LTTV to control tracing and analyse traces</li>
 369 <PRE>
 370 lttv-gui (or /usr/local/bin/lttv-gui)
 371   - Spot the "Tracing Control" icon : click on it
 372       (it's a traffic light icon)
 373     - enter the root password
 374     - click "start"
 375     - click "stop"
 376     - Yes
 377       * You should now see a trace
 378 </PRE>
 379
 380 <li>Use text mode LTTng to control tracing</li>
 381 <PRE>
 382 The tracing can be controlled from a terminal by using the lttctl command (as
 383 root).
 384
 385 Start tracing :
 386
 387 lttctl -C -w /tmp/trace1 trace1
 388
 389 Stop tracing and destroy trace channels :
 390
 391 lttctl -D trace1
 392
 393 see lttctl --help for details.
 394 </PRE>
 395 <p>
 396 (note : to see if the buffers has been filled, look at the dmesg output after
 397 lttctl -R or after stopping tracing from the GUI, it will show an event lost
 398 count. If it is the case, try using larger buffers. See lttctl --help to learn
 399 how. lttv now also shows event lost messages in the console when loading a trace
 400 with missing events or lost subbuffers.)
 401
 402 <li>Use text mode LTTV</li>
 403 <p>
 404 Feel free to look in /usr/local/lib/lttv/plugins to see all the text and
 405 graphical plugins available.
 406 <p>
 407 For example, a simple trace dump in text format is available with :
 408 <PRE>
 409 lttv -m textDump -t /tmp/trace
 410 </PRE>
 411 <p>
 412 See lttv -m textDump --help for detailed command line options of textDump.
 413 <p>
 414 It is, in the current state of the project, very useful to use "grep" on the
 415 text output to filter by specific event fields. You can later copy the timestamp
 416 of the events to the clipboard and paste them in the GUI by clicking on the
 417 bottom right label "Current time". Support for this type of filtering should
 418 be added to the filter module soon.
 419
 420 <li>Hybrid mode</li>
 421 <p>
 422 Starting from LTTng 0.5.105 and ltt-control 0.20, a new mode can be used :
 423 hybrid. It can be especially useful when studying big workloads on a long period
 424 of time.
 425 <p>
 426 When using this mode, the most important, low rate control information will be
 427 recorded during all the trace by lttd (i.e. process creation/exit). The high
 428 rate information (i.e. interrupt/traps/syscall entry/exit) will be kept in a
 429 flight recorder buffer (now named flight-channelname_X).
 430 <p>
 431 The following lttctl commands take an hybrid trace :
 432 <p>
 433 Create trace channel, start lttd on normal channels, start tracing:
 434 <PRE>
 435 lttctl -C -w /tmp/trace2 -o channel.kernel.overwrite=1 trace2
 436 </PRE>
 437 <p>
 438 Stop tracing, start lttd on flight recorder channels, destroy trace channels :
 439 <PRE>
 440 lttctl -D -w /tmp/trace2 trace2
 441 </PRE>
 442 <p>
 443 Each "overwrite" channel is flight recorder channel.
 444
 445 <li>Flight recorder mode</li>
 446 <p>
 447 The flight recorder mode writes data into overwritten buffers for all channels,
 448 including control channels, except for the facilities tracefiles. It consists of
 449 setting all channels to "overwrite".
 450 <p>
 451 The following lttctl commands take a flight recorder trace :
 452 <PRE>
 453 lttctl -C -w /tmp/trace3 -o channel.all.overwrite=1 trace3
 454 ...
 455 lttctl -D -w /tmp/trace3 trace3
 456 </PRE>
 457
 458 <hr />
 459
 460
 461 <h2><a href="#TOCsection3" name="section3">Adding new instrumentations with the
 462 markers</a></h2>
 463 <p>
 464
 465 <p>
 466 See Documentation/markers.txt and Documentation/tracepoints.txt in your kernel
 467 tree.
 468
 469 <li>Add new events to userspace programs with
 470 <a href="http://ltt.polymtl.ca/packages/">userspace markers packages</a></li>
 471
 472 <p>
 473 Get the latest markers-userspace-*.tar.bz2 and see the Makefile and examples. It
 474 allows inserting markers in executables and libraries, currently only on x86_32
 475 and x86_64.
 476 See <a
 477 href="http://ltt.polymtl.ca/packages/markers-userspace-0.5.tar.bz2">markers-userspace-0.5.tar.bz2</a> or more recent.
 478
 479 <p>
 480 Note that a new design document for a 3rd generation of tracepoint/marker-based
 481 userspace tracing is available at <a
 482 href="http://ltt.polymtl.ca/svn/trunk/lttv/doc/developer/ust.html">LTTng User-space Tracing
 483 Design"</a>. This new infrastructure is not yet implemented.
 484
 485 <p>
 486 The easy quick-and-dirty way to perform userspace tracing is currently to write
 487 an string to /mnt/debugfs/ltt/write_event. See <a
 488 href="#userspacetracing">Userspace tracing</a> in the
 489 installation for sources section of this document.
 490
 491 <hr />
 492
 493 <h2><a href="#TOCsection4" name="section4">Creating Debian or RPM packages</a></h2>
 494 <p>
 495
 496 <li>Create custom LTTV Debian packages</li>
 497
 498 <PRE>
 499 Use : dpkg-buildpackage -rfakeroot
 500 </PRE>
 501 <p>
 502 You should then have your LTTV .deb files created for your architecture.
 503
 504 <li>Create custom LTTng packages</li>
 505 <p>
 506 For building LTTng Debian packages :
 507 get the build tree with patches applies as explained in section 2.
 508
 509 <PRE>
 510 make menuconfig (or xconfig or config) (customize your configuration)
 511 make-kpkg kernel_image
 512 </PRE>
 513 <p>
 514 You will then see your freshly created .deb in /usr/src. Install it with
 515 <PRE>
 516 dpkg -i /usr/src/(image-name).deb
 517 </PRE>
 518 <p>
 519 Then, follow the section "Editing the system wide configuration" in section 2.
 520
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