The LTTng Documentation
=======================
Philippe Proulx <pproulx@efficios.com>
-v2.7, 25 October 2016
+v2.7, 24 July 2017
include::../common/copyright.txt[]
+include::../common/warning-not-maintained.txt[]
+
+
include::../common/welcome.txt[]
[[installing-lttng]]
== Installation
+include::../common/warning-no-installation.txt[]
+
**LTTng** is a set of software <<plumbing,components>> which interact to
<<instrumenting,instrument>> the Linux kernel and user applications, and
to <<controlling-tracing,control tracing>> (start and stop
trace user applications.
Most distributions mark the LTTng-modules and LTTng-UST packages as
-optional when installing LTTng-tools (which is always required). In the
-following sections, we always provide the steps to install all three,
-but note that:
+optional when installing LTTng-tools (which is always required). Note
+that:
* You only need to install LTTng-modules if you intend to trace the
Linux kernel.
* You only need to install LTTng-UST if you intend to trace user
applications.
-[role="growable"]
-.Availability of LTTng{nbsp}{revision} for major Linux distributions.
-|====
-|Distribution |Available in releases |Alternatives
-
-|Ubuntu
-|<<ubuntu,Ubuntu{nbsp}16.04 _Xenial Xerus_>>
-|LTTng{nbsp}2.8 for Ubuntu{nbsp}16.10 _Yakkety Yak_.
-
-LTTng{nbsp}{revision} for Ubuntu{nbsp}12.04 _Precise Pangolin_,
-Ubuntu{nbsp}14.04 _Trusty Tahr_, and Ubuntu{nbsp}16.04 _Xenial Xerus_:
-<<ubuntu-ppa,use the LTTng Stable{nbsp}{revision} PPA>>.
-
-<<building-from-source,Build LTTng{nbsp}{revision} from source>> for
-other Ubuntu releases.
-
-|Fedora
-|_Not available_
-|LTTng{nbsp}{revision} for Fedora{nbsp}25 and Fedora{nbsp}26 (not
-released yet).
-
-<<building-from-source,Build LTTng{nbsp}{revision} from source>> for
-other Fedora releases.
-
-|Debian
-|_Not available_
-|LTTng{nbsp}2.8 for Debian "stretch" (testing).
-
-<<building-from-source,Build LTTng{nbsp}{revision} from source>> for
-other Debian releases.
-
-|openSUSE
-|<<opensuse,openSUSE Leap{nbsp}42.1>>
-|<<building-from-source,Build LTTng{nbsp}{revision} from source>> for
-other openSUSE releases.
-
-|Arch Linux
-|_Not available_
-|<<building-from-source,Build LTTng{nbsp}{revision} from source>>.
-
-|Alpine Linux
-|_Not available_
-|LTTng{nbsp}2.8 for Alpine Linux "edge".
-
-LTTng{nbsp}2.8 for Alpine Linux{nbsp}3.5 (not released yet).
-
-<<building-from-source,Build LTTng{nbsp}{revision} from source>> for
-other Alpine Linux releases.
-
-|RHEL and SLES
-|See http://packages.efficios.com/[EfficiOS Enterprise Packages].
-|
-
-|Buildroot
-|<<"buildroot","Buildroot{nbsp}2016.02, Buildroot{nbsp}2016.05,
-and Buildroot{nbsp}2016.08">>
-|LTTng{nbsp}2.8 for Buildroot{nbsp}2016.11 (not released yet).
-
-<<building-from-source,Build LTTng{nbsp}{revision} from source>> for
-other Buildroot releases.
-
-|OpenEmbedded and Yocto
-|<<oe-yocto,Yocto Project{nbsp}2.1 _Krogoth_>> (`openembedded-core` layer)
-|LTTng{nbsp}2.8 for Yocto Project{nbsp}2.2 _Morty_.
-
-<<building-from-source,Build LTTng{nbsp}{revision} from source>> for
-other Yocto releases.
-|====
-
-
-[[ubuntu]]
-=== [[ubuntu-official-repositories]]Ubuntu
-
-LTTng{nbsp}{revision} is available on Ubuntu 16.04 _Xenial Xerus_. For
-previous releases of Ubuntu, <<ubuntu-ppa,use the LTTng
-Stable{nbsp}{revision} PPA>>.
-
-To install LTTng{nbsp}{revision} on Ubuntu{nbsp}16.04 _Xenial Xerus_:
-
-. Install the main LTTng{nbsp}{revision} packages:
-+
---
-[role="term"]
-----
-sudo apt-get install lttng-tools
-sudo apt-get install lttng-modules-dkms
-sudo apt-get install liblttng-ust-dev
-----
---
-
-. **If you need to instrument and trace
- <<java-application,Java applications>>**, install the LTTng-UST
- Java agent:
-+
---
-[role="term"]
-----
-sudo apt-get install liblttng-ust-agent-java
-----
---
-
-. **If you need to instrument and trace
- <<python-application,Python applications>>**, install the
- LTTng-UST Python agent:
-+
---
-[role="term"]
-----
-sudo apt-get install python3-lttngust
-----
---
-
-
-[[ubuntu-ppa]]
-==== noch:{LTTng} Stable {revision} PPA
-
-The
-https://launchpad.net/~lttng/+archive/ubuntu/stable-{revision}[LTTng Stable{nbsp}{revision} PPA]
-offers the latest stable LTTng{nbsp}{revision} packages for:
-
-* Ubuntu{nbsp}12.04 _Precise Pangolin_
-* Ubuntu{nbsp}14.04 _Trusty Tahr_
-* Ubuntu{nbsp}16.04 _Xenial Xerus_
-
-To install LTTng{nbsp}{revision} from the LTTng Stable{nbsp}{revision}
-PPA:
-
-. Add the LTTng Stable{nbsp}{revision} PPA repository and update the
- list of packages:
-+
---
-[role="term"]
-----
-sudo apt-add-repository ppa:lttng/stable-2.7
-sudo apt-get update
-----
---
-
-. Install the main LTTng{nbsp}{revision} packages:
-+
---
-[role="term"]
-----
-sudo apt-get install lttng-tools
-sudo apt-get install lttng-modules-dkms
-sudo apt-get install liblttng-ust-dev
-----
---
-
-. **If you need to instrument and trace
- <<java-application,Java applications>>**, install the LTTng-UST
- Java agent:
-+
---
-[role="term"]
-----
-sudo apt-get install liblttng-ust-agent-java
-----
---
-
-. **If you need to instrument and trace
- <<python-application,Python applications>>**, install the
- LTTng-UST Python agent:
-+
---
-[role="term"]
-----
-sudo apt-get install python3-lttngust
-----
---
-
-
-[[opensuse]]
-=== noch:{openSUSE}/RPM
-
-To install LTTng{nbsp}{revision} on openSUSE Leap{nbsp}42.1:
-
-* Install the main LTTng{nbsp}{revision} packages:
-+
---
-[role="term"]
-----
-sudo zypper install lttng-tools
-sudo zypper install lttng-modules
-sudo zypper install lttng-ust-devel
-----
---
-
-[IMPORTANT]
-.Java and Python application instrumentation and tracing
-====
-If you need to instrument and trace <<java-application,Java
-applications>> on openSUSE, you need to build and install
-LTTng-UST{nbsp}{revision} <<building-from-source,from source>> and pass
-the `--enable-java-agent-jul`, `--enable-java-agent-log4j`, or
-`--enable-java-agent-all` options to the `configure` script, depending
-on which Java logging framework you use.
-
-If you need to instrument and trace <<python-application,Python
-applications>> on openSUSE, you need to build and install
-LTTng-UST{nbsp}{revision} from source and pass the
-`--enable-python-agent` option to the `configure` script.
-====
-
-
-[[buildroot]]
-=== Buildroot
-
-To install LTTng{nbsp}{revision} on Buildroot{nbsp}2016.02,
-Buildroot{nbsp}2016.05, or Buildroot{nbsp}2016.08:
-
-. Launch the Buildroot configuration tool:
-+
---
-[role="term"]
-----
-make menuconfig
-----
---
-
-. In **Kernel**, check **Linux kernel**.
-. In **Toolchain**, check **Enable WCHAR support**.
-. In **Target packages**{nbsp}→ **Debugging, profiling and benchmark**,
- check **lttng-modules** and **lttng-tools**.
-. In **Target packages**{nbsp}→ **Libraries**{nbsp}→
- **Other**, check **lttng-libust**.
-
-
-[[oe-yocto]]
-=== OpenEmbedded and Yocto
-
-LTTng{nbsp}{revision} recipes are available in the
-http://layers.openembedded.org/layerindex/branch/master/layer/openembedded-core/[`openembedded-core`]
-layer for Yocto Project{nbsp}2.1 _Krogoth_ under the following names:
-
-* `lttng-tools`
-* `lttng-modules`
-* `lttng-ust`
-
-With BitBake, the simplest way to include LTTng recipes in your target
-image is to add them to `IMAGE_INSTALL_append` in path:{conf/local.conf}:
-
-----
-IMAGE_INSTALL_append = " lttng-tools lttng-modules lttng-ust"
-----
-
-If you use Hob:
-
-. Select a machine and an image recipe.
-. Click **Edit image recipe**.
-. Under the **All recipes** tab, search for **lttng**.
-. Check the desired LTTng recipes.
-
-[IMPORTANT]
-.Java and Python application instrumentation and tracing
-====
-If you need to instrument and trace <<java-application,Java
-applications>> on openSUSE, you need to build and install
-LTTng-UST{nbsp}{revision} <<building-from-source,from source>> and pass
-the `--enable-java-agent-jul`, `--enable-java-agent-log4j`, or
-`--enable-java-agent-all` options to the `configure` script, depending
-on which Java logging framework you use.
-
-If you need to instrument and trace <<python-application,Python
-applications>> on openSUSE, you need to build and install
-LTTng-UST{nbsp}{revision} from source and pass the
-`--enable-python-agent` option to the `configure` script.
-====
-
-
-[[enterprise-distributions]]
-=== RHEL, SUSE, and other enterprise distributions
-
-To install LTTng on enterprise Linux distributions, such as Red Hat
-Enterprise Linux (RHEL) and SUSE Linux Enterprise Server (SUSE), please
-see http://packages.efficios.com/[EfficiOS Enterprise Packages].
-
[[building-from-source]]
=== Build from source
An **event** is the consequence of the execution of an _instrumentation
point_, like a tracepoint that you manually place in some source code,
or a Linux kernel KProbe. An event is said to _occur_ at a specific
-time. Different actions can be taken upon the occurance of an event,
+time. Different actions can be taken upon the occurrence of an event,
like record the event's payload to a buffer.
An **event record** is the representation of an event in a sub-buffer. A
* **LTTng-tools**: Libraries and command-line interface to
control tracing sessions.
** <<lttng-sessiond,Session daemon>> (man:lttng-sessiond(8)).
-** <<lttng-consumerd,Consumer daemon>> (man:lttng-consumerd(8)).
+** <<lttng-consumerd,Consumer daemon>> (cmd:lttng-consumerd).
** <<lttng-relayd,Relay daemon>> (man:lttng-relayd(8)).
** <<liblttng-ctl-lttng,Tracing control library>> (`liblttng-ctl`).
** <<lttng-cli,Tracing control command-line tool>> (man:lttng(1)).
.The consumer daemon.
image::plumbing-consumerd.png[]
-The _consumer daemon_, man:lttng-consumerd(8), is a daemon which shares
+The _consumer daemon_, cmd:lttng-consumerd, is a daemon which shares
ring buffers with user applications or with the LTTng kernel modules to
collect trace data and send it to some location (on disk or to a
<<lttng-relayd,relay daemon>> over the network). The consumer daemon
Once you <<tpp-header,create a tracepoint provider header file>>, you
can use the `tracepoint()` macro in your application's
source code to insert the tracepoints that this header
-<<defining-tracepoints,defined>> defines.
+<<defining-tracepoints,defines>>.
The `tracepoint()` macro takes at least two parameters: the tracepoint
provider name and the tracepoint name. The corresponding tracepoint
`libemon.so`::
User library shared object file.
-The red star indicates that this object file is instrumented
-(contains code which uses the `tracepoint()` macro). The spring
-symbol between the application and a library means the application is
-linked with the library at build time.
+We use the following symbols in the diagrams of table below:
+
+[role="img-100"]
+.Symbols used in the build scenario diagrams.
+image::ust-sit-symbols.png[]
We assume that path:{.} is part of the env:LD_LIBRARY_PATH environment
variable in the following instructions.
To build the instrumented user library:
. In path:{emon.c}, before including path:{tpp.h}, add the
- following line:
+ following lines:
+
--
[source,c]
To build the instrumented user library:
. In path:{emon.c}, before including path:{tpp.h}, add the
- following line:
+ following lines:
+
--
[source,c]
To build the instrumented user library:
. In path:{emon.c}, before including path:{tpp.h}, add the
- following line:
+ following lines:
+
--
[source,c]
To build the instrumented user library:
. In path:{emon.c}, before including path:{tpp.h}, add the
- following line:
+ following lines:
+
--
[source,c]
[[prebuilt-ust-helpers]]
=== Prebuilt user space tracing helpers
-The LTTng-UST package provides a few helpers in the form or preloadable
+The LTTng-UST package provides a few helpers in the form of preloadable
shared objects which automatically instrument system functions and
calls.
entry is enough to create a call graph, since an event record always
contains the ID of the CPU that generated it.
+
-You can use a tool like
-https://sourceware.org/binutils/docs/binutils/addr2line.html[cmd:addr2line]
-to convert function addresses back to source file names and
-line numbers.
+You can use a tool like man:addr2line(1) to convert function addresses
+back to source file names and line numbers.
* **path:{liblttng-ust-cyg-profile.so}** is a more robust variant
which also works in use cases where event records might get discarded or
----
--
-. Edit path:{probes/Makefile} and add your new kernel module object
+. Edit path:{probes/KBuild} and add your new kernel module object
next to the existing ones:
+
--
[source,make]
-.path:{probes/Makefile}
+.path:{probes/KBuild}
----
# ...
--
[role="term"]
----
-lttng create --output=/tmp/some-directory my-session
+lttng create my-session --output=/tmp/some-directory
----
--
--
[role="term"]
----
-lttng create --live my-session
+lttng create my-session --live
----
--
+
--
[role="term"]
----
-lttng create --snapshot my-session
+lttng create my-session --snapshot
----
--
+
--
[role="term"]
----
-lttng create --shm-path=/path/to/shm
+lttng create my-session -shm-path=/path/to/shm
----
--
or a Linux kernel KProbe.
+
An event is said to _occur_ at a specific time. Different actions can
-be taken upon the occurance of an event, like record the event's payload
+be taken upon the occurrence of an event, like record the event's payload
to a sub-buffer.
<<channel-overwrite-mode-vs-discard-mode,event loss mode>>::