The LTTng Documentation
=======================
Philippe Proulx <pproulx@efficios.com>
-v2.9, 2 December 2016
+v2.9, 6 December 2016
include::../common/copyright.txt[]
[[whats-new]]
== What's new in LTTng {revision}?
+LTTng{nbsp}{revision} bears the name _Joannès_. A Berliner Weisse style
+beer from the http://letreflenoir.com/[Trèfle Noir] microbrewery in
+https://en.wikipedia.org/wiki/Rouyn-Noranda[Rouyn-Noranda], the
+https://www.beeradvocate.com/beer/profile/20537/238967/[_**Joannès**_]
+is a tangy beer with a distinct pink dress and intense fruit flavor,
+thanks to the presence of fresh blackcurrant grown in Témiscamingue.
+
+New features and changes in LTTng{nbsp}{revision}:
+
* **Tracing control**:
** You can override the name or the URL of a tracing session
configuration when you use man:lttng-load(1) thanks to the new
|====
|Distribution |Available in releases |Alternatives
-|Ubuntu
+|https://www.ubuntu.com/[Ubuntu]
|Ubuntu{nbsp}14.04 _Trusty Tahr_ and Ubuntu{nbsp}16.04 _Xenial Xerus_:
<<ubuntu-ppa,use the LTTng Stable{nbsp}{revision} PPA>>.
|link:/docs/v2.8#doc-ubuntu[LTTng{nbsp}2.8 for Ubuntu{nbsp}16.10 _Yakkety Yak_].
<<building-from-source,Build LTTng{nbsp}{revision} from source>> for
other Ubuntu releases.
-|Fedora
+|https://getfedora.org/[Fedora]
|_Not available_
|<<building-from-source,Build LTTng-modules{nbsp}{revision} from
source>>.
-|Debian
+|https://www.debian.org/[Debian]
|_Not available_
|<<building-from-source,Build LTTng-modules{nbsp}{revision} from
source>>.
-|openSUSE
+|https://www.opensuse.org/[openSUSE]
|_Not available_
|<<building-from-source,Build LTTng-modules{nbsp}{revision} from
source>>.
-|Arch Linux
+|https://www.archlinux.org/[Arch Linux]
|<<arch-linux,Latest AUR packages>>.
|
-|Alpine Linux
+|https://alpinelinux.org/[Alpine Linux]
|_Not available_
|link:/docs/v2.8#doc-alpine-linux[LTTng{nbsp}2.8 for Alpine Linux{nbsp}"edge"].
<<building-from-source,Build LTTng{nbsp}{revision} from source>> for
other Alpine Linux releases.
-|RHEL and SLES
+|https://www.redhat.com/[RHEL] and https://www.suse.com/[SLES]
|See http://packages.efficios.com/[EfficiOS Enterprise Packages].
|
-|Buildroot
+|https://buildroot.org/[Buildroot]
|_Not available_
|link:/docs/v2.8#doc-buildroot[LTTng{nbsp}2.8 for Buildroot{nbsp}2016.11].
<<building-from-source,Build LTTng{nbsp}{revision} from source>> for
other Buildroot releases.
-|OpenEmbedded and Yocto
+|http://www.openembedded.org/wiki/Main_Page[OpenEmbedded] and
+https://www.yoctoproject.org/[Yocto]
|_Not available_
|link:/docs/v2.8#doc-oe-yocto[LTTng{nbsp}2.8 for Yocto Project{nbsp}2.2 _Morty_]
(`openembedded-core` layer).
The following command lines start with cmd:sudo because you need root
privileges to trace the Linux kernel. You can avoid using cmd:sudo if
-your Unix user is a member of the <<lttng-sessiond,tracing group>>.
+your Unix user is a member of the <<tracing-group,tracing group>>.
-. Create a <<tracing-session,tracing session>>:
+. Create a <<tracing-session,tracing session>> which writes its traces
+ to dir:{/tmp/my-kernel-trace}:
+
--
[role="term"]
----
-sudo lttng create my-kernel-session
+sudo lttng create my-kernel-session --output=/tmp/my-kernel-trace
----
--
[role="term"]
----
lttng list --kernel
+lttng list --kernel --syscall
----
--
-. Create an <<event,event rule>> which matches the desired event names,
- for example `sched_switch` and `sched_process_fork`:
+. Create <<event,event rules>> which match the desired instrumentation
+ point names, for example the `sched_switch` and `sched_process_fork`
+ tracepoints, and the man:open(2) and man:close(2) system calls:
+
--
[role="term"]
----
sudo lttng enable-event --kernel sched_switch,sched_process_fork
+sudo lttng enable-event --kernel --syscall open,close
----
--
+
-You can also create an event rule which _matches_ all the Linux kernel
+You can also create an event rule which matches _all_ the Linux kernel
tracepoints (this will generate a lot of data when tracing):
+
--
----
--
-. Start tracing:
+. <<basic-tracing-session-control,Start tracing>>:
+
--
[role="term"]
. Do some operation on your system for a few seconds. For example,
load a website, or list the files of a directory.
-. Stop tracing and destroy the tracing session:
+. <<basic-tracing-session-control,Stop tracing>> and destroy the
+ tracing session:
+
--
[role="term"]
The man:lttng-destroy(1) command does not destroy the trace data; it
only destroys the state of the tracing session.
-By default, LTTng saves the traces in
-+$LTTNG_HOME/lttng-traces/__name__-__date__-__time__+,
-where +__name__+ is the tracing session name. Note that the
-env:LTTNG_HOME environment variable defaults to `$HOME` if not set.
+. For the sake of this example, make the recorded trace accessible to
+ the non-root users:
++
+--
+[role="term"]
+----
+sudo chown -R $(whoami) /tmp/my-kernel-trace
+----
+--
See <<viewing-and-analyzing-your-traces,View and analyze the
recorded events>> to view the recorded events.
----
--
-. Start tracing:
+. <<basic-tracing-session-control,Start tracing>>:
+
--
[role="term"]
. Go back to the running `hello` application and press Enter. The
program executes all `tracepoint()` instrumentation points and exits.
-. Stop tracing and destroy the tracing session:
+. <<basic-tracing-session-control,Stop tracing>> and destroy the
+ tracing session:
+
--
[role="term"]
By default, LTTng saves the traces in
+$LTTNG_HOME/lttng-traces/__name__-__date__-__time__+,
-where +__name__+ is the tracing session name. Note that the
+where +__name__+ is the tracing session name. The
env:LTTNG_HOME environment variable defaults to `$HOME` if not set.
See <<viewing-and-analyzing-your-traces,View and analyze the
NOTE: This section assumes that the traces recorded during the previous
tutorials were saved to their default location, in the
-dir:{$LTTNG_HOME/lttng-traces} directory. Note that the env:LTTNG_HOME
+dir:{$LTTNG_HOME/lttng-traces} directory. The env:LTTNG_HOME
environment variable defaults to `$HOME` if not set.
[role="term"]
----
-babeltrace ~/lttng-traces/my-kernel-session* | grep sys_
+babeltrace /tmp/my-kernel-trace | grep _switch
----
You can pipe the output of cmd:babeltrace into a tool like man:wc(1) to
[role="term"]
----
-babeltrace ~/lttng-traces/my-kernel-session* | grep sys_read | wc --lines
+babeltrace /tmp/my-kernel-trace | grep _open | wc --lines
----
[role="term"]
----
-python3 top5proc.py ~/lttng-traces/my-kernel-session*/kernel
+python3 top5proc.py /tmp/my-kernel-trace/kernel
----
Output example:
belongs to the Linux kernel <<domain,tracing domain>>. However, unlike
other instrumentation points in the kernel tracing domain, **any Unix
user** can <<enabling-disabling-events,create an event rule>> which
-matches its event name, not only the root user or users in the tracing
-group.
+matches its event name, not only the root user or users in the
+<<tracing-group,tracing group>>.
To use the LTTng logger:
<<domain,tracing domain>>::
A namespace for event sources.
-tracing group::
+<<tracing-group,tracing group>>::
The Unix group in which a Unix user can be to be allowed to trace the
Linux kernel.
projects / lttng-docs.git / blobdiff