-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.
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
@@ -43,21 +82,33 @@ To see the list of compatibilities between LTTng, ltt-control, LTTV, please
refer to :
LTTng+LTTV versions compatibility
-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.
-Supported architectures :
+
-
Tools needed to follow the package download steps : @@ -130,7 +181,7 @@ href="http://ltt.polymtl.ca/svn/trunk/lttv/doc/developer/lttng-lttv-compatibilit versions compatibility. -
su - @@ -142,7 +193,7 @@ bzip2 -cd patch-2.6.X-lttng-0.x.xx.tar.bz2 | tar xvof --
su - @@ -158,7 +209,7 @@ mv linux-2.6.X linux-2.6.X-lttng-0.x.xx-
su - @@ -215,7 +266,8 @@ Select the Linux 2.6.X-lttng-0.x.xx kernel in your boot loader. ---
You must activate debugfs and specify a mount point. This is typically done in @@ -290,7 +342,9 @@ echo trap-trace >> /etc/modules #echo lockdep-trace >> /etc/modules -
(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.) @@ -308,7 +362,7 @@ make make install -
Make sure you selected the kernel menuconfig option : @@ -324,8 +378,9 @@ channel : userspace event name : event-
su - @@ -338,27 +393,20 @@ system) ./configure make make install - - -
ltt-armall-
lttv-gui (or /usr/local/bin/lttv-gui)
- Spot the "Tracing Control" icon : click on it
@@ -370,7 +418,7 @@ lttv-gui (or /usr/local/bin/lttv-gui)
* You should now see a trace
-The tracing can be controlled from a terminal by using the lttctl command (as root). @@ -384,7 +432,7 @@ Stop tracing and destroy trace channels : lttctl -D trace1 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 @@ -392,20 +440,17 @@ count. If it is the case, try using larger buffers. See lttctl --help to learn how. lttv now also shows event lost messages in the console when loading a trace with missing events or lost subbuffers.) -
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 @@ -413,19 +458,16 @@ 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. -
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 :
@@ -441,61 +483,138 @@ lttctl -D -w /tmp/trace2 trace2
Each "overwrite" channel is flight recorder channel. -
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". -
The following lttctl commands take a flight recorder trace : -
lttctl -C -w /tmp/trace3 -o channel.all.overwrite=1 trace3 ... lttctl -D -w /tmp/trace3 trace3-************************************************************** -** Section 4 * Adding new instrumentations with the markers ** -************************************************************** +
+ +
+See Documentation/markers.txt +and Documentation/tracepoints.txt in your kernel tree. +
+Also see ltt/probes/ +for LTTng probe examples. -* Add new events to userspace programs with userspace markers -http://ltt.polymtl.ca/packages/ +
+Note that a new design document for a 3rd generation of tracepoint/marker-based +userspace tracing is available at LTTng User-space Tracing +Design. This new infrastructure is not yet implemented. -* Create custom LTTV Debian packages +
+The easy quick-and-dirty way to perform userspace tracing is currently to write +an string to /mnt/debugfs/ltt/write_event. See Userspace tracing in the +installation for sources section of this document. -Use : dpkg-buildpackage -rfakeroot +
-* Create custom LTTng packages +
+Use : dpkg-buildpackage -rfakeroot ++
+You should then have your LTTV .deb files created for your architecture. -Get the build tree with patches applies as explained in section 2. +
+For building LTTng Debian packages : +get the build tree with patches applies as explained in section 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 - ++
Then, follow the section "Editing the system wide configuration" in section 2. +
+A few examples of successful LTTng users : +