lttng-add-context man page
lttng-add-context — Add context fields to an LTTng channel
Add context fields to a channel:
lttng [GENERAL OPTIONS] add-context (--kernel | --userspace | --jul | --log4j) [--session=SESSION] [--channel=CHANNEL] --type=TYPE [--type=TYPE]...
List the available context fields:
lttng [GENERAL OPTIONS] add-context --list
The lttng add-context command adds one or more context fields to a channel.
Channels are created with the lttng-enable-channel(1) command.
When context fields are added to a channel, all the events emitted within this channel contain the dynamic values of those context fields.
If the --session option is omitted, the current tracing session is used. If the --channel option is omitted, the context fields are added to all the selected tracing session’s channels.
Many context fields can be added to a channel at once by repeating the --type option.
perf counters are available as per-CPU (perf:cpu: prefix) as well as per-thread (perf:thread: prefix) counters. Currently, per-CPU counters can only be used in the Linux kernel tracing domain, while per-thread counters can only be used in the user space tracing domain.
It is also possible to enable PMU counters by raw ID using the perf:cpu:raw:rN:NAME (Linux kernel tracing domain) or perf:thread:raw:rN:NAME (user space tracing domain), with:
A hexadecimal event descriptor which is the same format as used by perf-record(1): a concatenation of the event number and umask value provided by the processor’s manufacturer. The possible values for this field are processor-specific.
Custom name to easily recognize the counter.
Application-specific context fields can be added to a channel using the following syntax:
Context type name.
Make sure to single-quote the type when running the command from a shell, as $ is a special character for variable substitution in most shells.
Use the --list option without other arguments to list the available context field names.
See the Limitations section below for a list of limitations to consider.
General options are described in lttng(1).
- -j, --jul
Add context to channel in the java.util.logging (JUL) domain.
- -k, --kernel
Add context to channel in the Linux kernel domain.
- -l, --log4j
Add context to channel in the Apache log4j domain.
- -u, --userspace
Add context to channel in the user space domain.
- -c CHANNEL, --channel=CHANNEL
Add context fields to a channel named CHANNEL instead of adding them to all the channels.
- -s SESSION, --session=SESSION
Add context fields to a channel in the tracing session named SESSION instead of the current tracing session.
List the available context fields. Use this option alone.
- -t TYPE, --type=TYPE
Add context field named TYPE. This option can be repeated as many times as needed on the command-line.
- -h, --help
Show command help.
This option, like lttng-help(1), attempts to launch /usr/bin/man to view the command’s man page. The path to the man pager can be overridden by the LTTNG_MAN_BIN_PATH environment variable.
List available command options.
As of this version of LTTng, it is not possible to add context fields to a channel once its tracing session has been started (see lttng-start(1)) at least once.
Set to 1 to abort the process after the first error is encountered.
Overrides the $HOME environment variable. Useful when the user running the commands has a non-writable home directory.
Absolute path to the man pager to use for viewing help information about LTTng commands (using lttng-help(1) or lttng COMMAND --help).
Path in which the session.xsd session configuration XML schema may be found.
Full session daemon binary path.
The --sessiond-path option has precedence over this environment variable.
Note that the lttng-create(1) command can spawn an LTTng session daemon automatically if none is running. See lttng-sessiond(8) for the environment variables influencing the execution of the session daemon.
User LTTng runtime configuration.
This is where the per-user current tracing session is stored between executions of lttng(1). The current tracing session can be set with lttng-set-session(1). See lttng-create(1) for more information about tracing sessions.
Default output directory of LTTng traces. This can be overridden with the --output option of the lttng-create(1) command.
User LTTng runtime and configuration directory.
Default location of saved user tracing sessions (see lttng-save(1) and lttng-load(1)).
System-wide location of saved tracing sessions (see lttng-save(1) and lttng-load(1)).
$LTTNG_HOME defaults to $HOME when not explicitly set.
Command warning (something went wrong during the command)
If you encounter any issue or usability problem, please report it on the LTTng bug tracker <https://bugs.lttng.org/projects/lttng-tools>.
- LTTng project website <http://lttng.org>
- LTTng documentation <http://lttng.org/docs>
- Git repositories <http://git.lttng.org>
- GitHub organization <http://github.com/lttng>
- Continuous integration <http://ci.lttng.org/>
- Mailing list <http://lists.lttng.org> for support and development: firstname.lastname@example.org
- IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net
This program is part of the LTTng-tools project.
LTTng-tools is distributed under the GNU General Public License version 2 <http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html>. See the LICENSE <https://github.com/lttng/lttng-tools/blob/master/LICENSE> file for details.
Special thanks to Michel Dagenais and the DORSAL laboratory <http://www.dorsal.polymtl.ca/> at École Polytechnique de Montréal for the LTTng journey.
Also thanks to the Ericsson teams working on tracing which helped us greatly with detailed bug reports and unusual test cases.
LTTng-tools was originally written by Mathieu Desnoyers, Julien Desfossez, and David Goulet. More people have since contributed to it.
LTTng-tools is currently maintained by Jérémie Galarneau <mailto:email@example.com>.
lttng(1), lttng-enable-event(1), lttng-ust(3).