Linux Trace Toolkit Quickstart ------------------------------ Author : Mathieu Desnoyers, September 2005 Last update : July 31, 2008 This document is made of four parts : the first one explains how to install LTTng and LTTV from Debian and RPM binary packages, the second one explains how to install LTTng and LTTV from sources and the third one describes the steps to follow to trace a system and view it. The fourth and last part explains briefly how to add a new trace point to the kernel and to user space applications. What you will typically want is to read sections 2 and 3 : install LTTng from sources and use it. These operations are made for installing the LTTng 0.12 tracer on a linux 2.6.X kernel. You will also find instructions for installation of LTTV 0.8.x : the Linux Trace Toolkit Viewer. To see the list of compatibilities between LTTng, ltt-control, LTTV, genevent and ltt-usertrace, please refer to : http://ltt.polymtl.ca > LTTng+LTTV versions compatibility The following lttng patch is necessary to have the tracing hooks in the kernel. The following ltt-control module controls the tracing. Required programs and libraries are assumed to be automatically installed in an installation with Debian or RPM packages. In the case of an installation from sources, the dependencies are listed. ** Current development status ** LTTng : supported architectures : Intel Pentium (UP/SMP) with TSC PowerPC 32 and 64 bits ARM x86_64 C2 Microsystems (variant of MIPS) LTTV : supported architectures : Intel i386 and better Intel 64 bits PowerPC 32 and 64 bits *********************************************************** ** Section 1 * Installation from Debian or RPM packages ** *********************************************************** ** NOTE : RPM and Debian packages are only made once a version has been thoroughly tested. If they do not exist at the moment, please install from sources (see section 2 below). To see the list of compatibilities between LTTng, ltt-control, LTTV, genevent and lttng-modules, please refer to http://ltt.polymtl.ca > LTTng+LTTV versions compatibility * Install from RPM packages on Fedora Core 4 : Get LTTV RPM from : http://ltt.polymtl.ca/packages/fedora/RPMS LTTV RPM are ready. LTTng kernel and lttng-modules RPM are available for some architectures (i586, i686). Feel free to help fix the spec files to have correct lttng-modules RPM package. * Install from .deb packages on Debian : You can use the ltt.polymtl.ca apt source to get LTTV for Debian : Add the following two sources to your /etc/apt/sources.list : deb http://ltt.polymtl.ca/packages/debian experimental main deb-src http://ltt.polymtl.ca/packages/debian experimental main * Install from precompiled binary packages (LTTV compiled only for i386, and LTTng only for i686 smp), perform the following : su - apt-get update apt-get install lttv lttv-doc apt-get install kernel-image-2.6.12-rc4-mm2-lttng-0.4.2 apt-get install lttng-modules-modules-2.6.12-rc4-mm2-lttng-0.4.2 * note : the packages are signed by myself. I am not considered a trusted Debian source yet, so warnings are normal. Then, follow the section "Editing the system wide configuration" in section 2. * Create custom LTTV Debian packages Binary packages are only available for i386. If you want to create your own LTTV packages for other platforms, do : su - cd /usr/src apt-get source lttv cd lttv-0.6.9 dpkg-buildpackage -rfakeroot You should then have your LTTV .deb files created for your architecture. * Create custom LTTng packages For building LTTng Debian packages : su - apt-get install kernel-source-2.6.12-rc4-mm2-lttng-0.4.2 cd /usr/src bzip2 -cd kernel-source-2.6.12-rc4-mm2-lttng-0.4.2.tar.bz2 | tar xvof - cd kernel-source-2.6.12-rc4-mm2-lttng-0.4.2 make menuconfig (or xconfig or config) (customize your configuration) make-kpkg kernel_image You will then see your freshly created .deb in /usr/src. Install it with dpkg -i /usr/src/(image-name).deb You will also need to create a package for the lttng-modules : su - cd /usr/src apt-get source lttng-modules cd kernel-source-2.6.12-rc4-mm2-lttng-0.4.2 make-kpkg --added_modules /usr/src/lttng-modules-0.3 modules_image You will then see your freshly created .deb in /usr/src. Install it with dpkg -i /usr/src/lttng-modules-modules-(your version).deb Then, follow the section "Editing the system wide configuration" in section 2. *********************************************************** ** Section 2 * Installation from sources ** *********************************************************** * Prerequisites Tools needed to follow the package download steps : o wget o bzip2 o gzip o tar You have to install the standard development libraries and programs necessary to compile a kernel : (from Documentation/Changes in the Linux kernel tree) o Gnu C 2.95.3 # gcc --version o Gnu make 3.79.1 # make --version o binutils 2.12 # ld -v o util-linux 2.10o # fdformat --version o module-init-tools 0.9.10 # depmod -V You might also want to have libncurses5 to have the text mode kernel configuration menu, but there are alternatives. Prerequisites for LTTV 0.x.x installation are : gcc 3.2 or better gtk 2.4 or better development libraries (Debian : libgtk2.0, libgtk2.0-dev) (Fedora : gtk2, gtk2-devel) note : For Fedora users : this might require at least core 3 from Fedora, or you might have to compile your own GTK2 library. glib 2.4 or better development libraries (Debian : libglib2.0-0, libglib2.0-dev) (Fedora : glib2, glib2-devel) libpopt development libraries (Debian : libpopt0, libpopt-dev) (Fedora : popt) libpango development libraries (Debian : libpango1.0, libpango1.0-dev) (Fedora : pango, pango-devel) libc6 development librairies (Debian : libc6, libc6-dev) (Fedora : glibc, glibc) * Getting the LTTng packages su - mkdir /usr/src/lttng cd /usr/src/lttng (see http://ltt.polymtl.ca/lttng for package listing) wget http://ltt.polymtl.ca/lttng/patch-2.6.X-lttng-0.x.xx.tar.bz2 bzip2 -cd patch-2.6.X-lttng-0.x.xx.tar.bz2 | tar xvof - * Getting LTTng kernel sources su - cd /usr/src wget http://kernel.org/pub/linux/kernel/v2.6/linux-2.6.X.tar.bz2 bzip2 -cd linux-2.6.X.tar.bz2 | tar xvof - cd linux-2.6.X - For LTTng 0.9.4- cat /usr/src/lttng/patch*-2.6.X-lttng-0.x.xx* | patch -p1 - For LTTng 0.9.5+ apply the patches in the order specified in the series file, or use quilt cd .. mv linux-2.6.X linux-2.6.X-lttng-0.x.xx * Installing a LTTng kernel su - cd /usr/src/linux-2.6.X-lttng-0.x.xx make menuconfig (or make xconfig or make config) Select the < Help > button if you are not familiar with kernel configuration. Items preceded by [*] means they has to be built into the kernel. Items preceded by [M] means they has to be built as modules. Items preceded by [ ] means they should be removed. go to the "General setup" section Select the following options : [*] Activate tracepoints [*] Activate markers [*] Activate userspace markers ABI <*> Compile generic tracing probes Linux Trace Toolkit ---> [LTTng fine-grained-timestamping] [*] Linux Trace Toolkit Instrumentation Support or <*> Linux Trace Toolkit Relay+DebugFS Support or <*> Linux Trace Toolkit Serializer or <*> Linux Trace Toolkit Marker Control or <*> Linux Trace Toolkit Tracer It makes no difference for the rest of the procedure whether the Tracer is compiled built-in or as a module. activate : [*] Align Linux Trace Toolkit Traces Linux Trace Toolkit Netlink Controller Linux Trace Toolkit State Dump your choice (see < Help >) : [ ] Write heartbeat event to shrink traces [ ] Support trace extraction from crash dump Select Select Select make make modules_install (if necessary, create a initrd with mkinitrd or your preferate alternative) (mkinitrd -o /boot/initrd.img-2.6.X-lttng-0.x.xx 2.6.X-lttng-0.x.xx) -- on X86, X86_64 make install reboot Select the Linux 2.6.17-lttng-0.x.xx kernel in your boot loader. -- on PowerPC cp vmlinux.strip /boot/vmlinux-2.6.X-lttng-0.x.xx cp System.map /boot/System.map-2.6.X-lttng-0.x.xx cp .config /boot/config-2.6.X-lttng-0.x.xx depmod -ae -F /boot/System.map-2.6.X-lttng-0.x.xx 2.6.X-lttng-0.x.xx mkinitrd /boot/initrd.img-2.6.X-lttng-0.x.xx 2.6.X-lttng-0.x.xx (edit /etc/yaboot.conf to add a new entry pointing to your kernel : the entry that comes first is the default kernel) ybin select the right entry at the yaboot prompt (see choices : tab, select : type the kernel name followed by enter) Select the Linux 2.6.17-lttng-0.x.xx kernel in your boot loader. -- * Editing the system wide configuration You must activate debugfs and specify a mount point. This is typically done in fstab such that it happens at boot time. If you have never used DebugFS before, these operation would do this for you : mkdir /mnt/debugfs cp /etc/fstab /etc/fstab.lttng.bkp echo "debugfs /mnt/debugfs debugfs rw 0 0" >> /etc/fstab then, rebooting or issuing the following command will activate debugfs : mount /mnt/debugfs You need to load the LTT modules to be able to control tracing from user space. This is done by issuing the following commands. Note however these commands load all LTT modules. Depending on what options you chose to compile statically, you may not need to issue all these commands. modprobe ltt-control modprobe ltt-marker-control modprobe ltt-tracer modprobe ltt-serialize modprobe ltt-relay modprobe ipc-trace modprobe kernel-trace modprobe mm-trace modprobe net-trace modprobe fs-trace If you want to have complete information about the kernel state (including all the process names), you need to load the ltt-statedump module. This is done by issuing the command : modprobe ltt-statedump You can automate at boot time loading the ltt-control module by : cp /etc/modules /etc/modules.bkp echo ltt-control >> /etc/modules echo ltt-marker-control >> /etc/modules echo ltt-tracer >> /etc/modules echo ltt-serialize >> /etc/modules echo ltt-relay >> /etc/modules echo ipc-trace >> /etc/modules echo kernel-trace >> /etc/modules echo mm-trace >> /etc/modules echo net-trace >> /etc/modules echo fs-trace >> /etc/modules * Getting and installing the ltt-control package (on the traced machine) (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.) su - cd /usr/src wget http://ltt.polymtl.ca/lttng/ltt-control-0.x-xxxx2006.tar.gz gzip -cd ltt-control-0.x-xxxx2006.tar.gz | tar xvof - cd ltt-control-0.x-xxxx2006 (refer to README to see the development libraries that must be installed on you system) ./configure make make install * Getting and installing the markers-userspace package for user space tracing See http://ltt.polymtl.ca/packages/markers-userspace-0.5.tar.bz2 or more recent. * Getting and installing the LTTV package (on the visualisation machine, same or different from the visualisation machine) su - cd /usr/src wget http://ltt.polymtl.ca/packages/LinuxTraceToolkitViewer-0.x.xx-xxxx2006.tar.gz gzip -cd LinuxTraceToolkitViewer-0.x.xx-xxxx2006.tar.gz | tar xvof - cd LinuxTraceToolkitViewer-0.x.xx-xxxx2006 (refer to README to see the development libraries that must be installed on your system) ./configure make make install *********************************************************** ** Section 3 * Using LTTng and LTTV ** *********************************************************** * Arm Linux Kernel Markers after each boot ltt-armall * Use graphical LTTV to control tracing and analyse traces lttv-gui (or /usr/local/bin/lttv-gui) - Spot the "Tracing Control" icon : click on it (it's a traffic light icon) - enter the root password - click "start" - click "stop" - Yes * You should now see a trace * Use text mode LTTng to control tracing The tracing can be controlled from a terminal by using the lttctl command (as root). Start tracing : lttctl -n trace -d -l /mnt/debugfs/ltt -t /tmp/trace Stop tracing and destroy trace channels : lttctl -n trace -R see lttctl --help for details. (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 count. If it is the case, try using larger buffers. See lttctl --help to learn how.) * Use text mode LTTV Feel free to look in /usr/local/lib/lttv/plugins to see all the text and graphical plugins available. For example, a simple trace dump in text format is available with : lttv -m textDump -t /tmp/trace see lttv -m textDump --help for detailed command line options of textDump. 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 of the events to the clipboard and paste them in the GUI by clicking on the bottom right label "Current time". Support for this type of filtering should be added to the filter module soon. * Hybrid mode 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. 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). The following lttctl commands take an hybrid trace : Create trace channel, start lttd on normal channels, start tracing: lttctl -n tracename -d -l /mnt/relayfs/ltt -t /tmp/trace1 -m hybrid Stop tracing, start lttd on flight recorder channels, destroy trace channels : lttctl -n tracename -f -l /mnt/relayfs/ltt -t /tmp/trace1 -m hybrid We will need to tweak what we consider "important" medium rate events. For instance, thread branding events are actually considered a "high rate" event when it should be considered "medium rate". The same should apply for the state dump process enumeration. * Flight recorder mode The flight recorder mode writes data into overwritten buffers for all channels, including control channels, except for the facilities tracefiles. The following lttctl commands take a flight recorder trace : lttctl -n trace -c -m flight lttd -n -d -t /tmp/trace -c /sys/kernel/debug/ltt lttctl -n trace -s .. do stuff lttctl -n trace -q lttd -f -d -t /tmp/trace -c /sys/kernel/debug/ltt lttctl -m trace -r *********************************************************** ** Section 4 * Adding new instrumentations with genevent ** *********************************************************** * Getting and installing genevent su - cd /usr/src wget http://ltt.polymtl.ca/packages/genevent-0.xx.tar.gz gzip -cd genevent-0.xx.tar.gz | tar xvof - cd genevent-0.xx make make install * Add new events to the kernel with genevent (deprecated in LTTng 0.9.x) su - cd /usr/local/share/ltt-control/facilities cp process.xml yourfacility.xml * edit yourfacility.xml to fit your needs. cd /tmp /usr/local/bin/genevent /usr/local/share/ltt-control/facilities/yourfacility.xml cp ltt-facility-yourfacility.h ltt-facility-id-yourfacility.h \ /usr/src/linux-2.6.17-lttng-0.x.xx8/include/ltt cp ltt-facility-loader-yourfacility.c ltt-facility-loader-yourfacility.h \ /usr/src/linux-2.6.17-lttng-0.x.xx/ltt/facilities * edit the kernel file you want to instrument to add a marker to it. See include/linux/marker.h. * create a dynamically loadable probe. See ltt/probes for examples. The probe will be connected to your marker and will typically call the logging functions found in the header file you created with genevent. * Add new kernel events *Important* note : in its current state, LTTng and LTTV needs the programmer to keep the marker/probe format string and the XML description of the event data types in sync by hand. Failure to do so will result in errors in LTTV. See the markers documentation to see how to describe the marker. You will need to clone probe modules found in ltt/probes to connect them to the markers so that the information can be recorded in the trace. * Add new events to userspace programs with genevent See http://ltt.polymtl.ca/ > USERSPACE TRACING QUICKSTART User-space tracing still uses genevent, which is subject to change in a near future.