lttng-add-context(1) — Linux manual page
LTTNG-ADD-CONTEXT(1) LTTng Manual LTTNG-ADD-CONTEXT(1)
NAME
lttng-add-context - Add context fields to an LTTng channel
SYNOPSIS
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
DESCRIPTION
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:
N
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.
NAME
Custom name to easily recognize the counter.
Application-specific context fields can be added to a channel
using the following syntax:
$app.PROVIDER:TYPE
with:
PROVIDER
Provider name.
TYPE
Context type name.
Note
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.
OPTIONS
General options are described in lttng(1).
Domain
One of:
-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.
Target
-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.
Context
--list
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.
Program information
-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-options
List available command options.
LIMITATIONS
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.
ENVIRONMENT VARIABLES
LTTNG_ABORT_ON_ERROR
Set to 1 to abort the process after the first error is
encountered.
LTTNG_HOME
Overrides the $HOME environment variable. Useful when the
user running the commands has a non-writable home directory.
LTTNG_MAN_BIN_PATH
Absolute path to the man pager to use for viewing help
information about LTTng commands (using lttng-help(1) or
lttng COMMAND --help).
LTTNG_SESSION_CONFIG_XSD_PATH
Path in which the session.xsd session configuration XML
schema may be found.
LTTNG_SESSIOND_PATH
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.
FILES
$LTTNG_HOME/.lttngrc
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.
$LTTNG_HOME/lttng-traces
Default output directory of LTTng traces. This can be
overridden with the --output option of the lttng-create(1)
command.
$LTTNG_HOME/.lttng
User LTTng runtime and configuration directory.
$LTTNG_HOME/.lttng/sessions
Default location of saved user tracing sessions (see
lttng-save(1) and lttng-load(1)).
/usr/local/etc/lttng/sessions
System-wide location of saved tracing sessions (see
lttng-save(1) and lttng-load(1)).
Note
$LTTNG_HOME defaults to $HOME when not explicitly set.
EXIT STATUS
0
Success
1
Command error
2
Undefined command
3
Fatal error
4
Command warning (something went wrong during the command)
BUGS
If you encounter any issue or usability problem, please report it
on the LTTng bug tracker <https://bugs.lttng.org/projects/lttng-
tools>.
RESOURCES
• LTTng project website <https://lttng.org>
• LTTng documentation <https://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: lttng-dev@lists.lttng.org
• IRC channel <irc://irc.oftc.net/lttng>: #lttng on
irc.oftc.net
COPYRIGHTS
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.
THANKS
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.
AUTHORS
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:jeremie.galarneau@efficios.com>.
SEE ALSO
lttng(1)
COLOPHON
This page is part of the LTTng-Tools ( LTTng tools) project.
Information about the project can be found at
⟨http://lttng.org/⟩. It is not known how to report bugs for this
man page; if you know, please send a mail to man-pages@man7.org.
This page was obtained from the project's upstream Git repository
⟨git://git.lttng.org/lttng-tools.git⟩ on 2019-11-19. (At that
time, the date of the most recent commit that was found in the
repository was 2019-11-14.) If you discover any rendering
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is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
LTTng 2.12.0-pre 10/29/2018 LTTNG-ADD-CONTEXT(1)
Pages that refer to this page: lttng(1), lttng-enable-event(1), lttng-ust(3), babeltrace2-filter.lttng-utils.debug-info(7)