Ubuntu Manpage: lttng-add-context - Add context fields to an LTTng channel

name
synopsis
description
options
environment variables
files
exit status
bugs
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thanks
authors
see also

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.

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.

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 <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: 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>.