Ubuntu Manpage: lttng-add-context - Add context fields to be recorded by LTTng

NAME

       lttng-add-context - Add context fields to be recorded by LTTng

SYNOPSIS

       Add context fields to be recorded to the event records of one or more channels:

       lttng [GENERAL OPTIONS] add-context
             (--kernel | --userspace | --jul | --log4j)
             [--session=SESSION] [--channel=CHANNEL]
             --type=TYPE [--type=TYPE]...

       List the available context field types:

       lttng [GENERAL OPTIONS] add-context --list

DESCRIPTION

The lttng add-context command can:

Without the --list option
Add one or more context fields to be recorded by LTTng to the event records of:

With the --session=SESSION option
The recording session named SESSION.

Without the --session option
The current recording session (see lttng-concepts(7) to learn more about the
current recording session).

With the --channel=CHANNEL
The channel named CHANNEL.

Without the --channel option
All the channels of the selected recording session.

With the --list option
List the available context field types.

See lttng-concepts(7) to learn more about recording sessions and channels.

Repeat the --type=TYPE option to add more than one context field to be recorded. TYPE is
one of:

• A statically-known, or built-in context field named.

• A perf counter name:

Per-CPU
Prefix: perf:cpu:

Only available with the --kernel option.

Per-thread
Prefix: perf:thread:

Only available with the --userspace, --jul, or --log4j option.

Add Performance Monitoring Unit (PMU) counter context fields by raw ID with the
perf:cpu:raw:rN:NAME (--kernel option) or perf:thread:raw:rN:NAME (--userspace, --jul,
or --log4j option) types, with:

N
A hexadecimal event descriptor which follows the perf-record(1) format: a
concatenation of the event number and umask value which the manufacturer of the
processor provides.

The possible values for this part are processor-specific.

NAME
Custom name to identify the counter.

• An LTTng application-specific context field name:

$app.PROVIDER:TYPE
+ PROVIDER:: Provider name.

TYPE
Context type name.

Only available with the --jul and --log4j options.

Important
Make sure to single-quote TYPE when you run the add-context command from a shell, as $
is a special character for variable substitution in most shells.

Note
As of LTTng 2.13.7, you may NOT add context fields to be recorded to the event records
of a given channel once its recording session has been started (see lttng-start(1)) at
least once.

See the “EXAMPLES” section below for usage examples.

OPTIONS

See lttng(1) for GENERAL OPTIONS.

Tracing domain
One of:

-j, --jul
Add context fields to be recorded to the event records of one or more channels of the
java.util.logging (JUL) tracing domain.

-k, --kernel
Add context fields to be recorded to the event records of one or more channels of the
Linux kernel tracing domain.

-l, --log4j
Add context fields to be recorded to the event records of one or more channels of the
Apache log4j tracing domain.

-u, --userspace
Add context fields to be recorded to the event records of one or more channels of the
user space tracing domain.

Recording target
-c CHANNEL, --channel=CHANNEL
Add context fields to be recorded to the event records of a channel named CHANNEL
instead of all the channels of the selected recording session.

-s SESSION, --session=SESSION
Add context fields to be recorded to the event records of one or more channels of the
recording session named SESSION instead of the current recording session.

Context field type
--list
List the available context field types.

You may NOT use this option with the --channel, --session, or --type options.

-t TYPE, --type=TYPE
Add a context field having the type TYPE to be recorded.

Repeat this option to add more than one context field.

Program information
-h, --help
Show help.

This option attempts to launch /usr/bin/man to view this manual page. Override the
manual pager path with the LTTNG_MAN_BIN_PATH environment variable.

--list-options
List available command options and quit.

EXIT STATUS

       0
           Success

       1
           Command error

       2
           Undefined command

       3
           Fatal error

       4
           Command warning (something went wrong during the command)

ENVIRONMENT

       LTTNG_ABORT_ON_ERROR
           Set to 1 to abort the process after the first error is encountered.

       LTTNG_HOME
           Path to the LTTng home directory.

           Defaults to $HOME.

           Useful when the Unix user running the commands has a non-writable home directory.

       LTTNG_MAN_BIN_PATH
           Absolute path to the manual pager to use to read the LTTng command-line help (with
           lttng-help(1) or with the --help option) instead of /usr/bin/man.

       LTTNG_SESSION_CONFIG_XSD_PATH
           Path to the directory containing the session.xsd recording session configuration XML
           schema.

       LTTNG_SESSIOND_PATH
           Absolute path to the LTTng session daemon binary (see lttng-sessiond(8)) to spawn from
           the lttng-create(1) command.

           The --sessiond-path general option overrides this environment variable.

FILES

       $LTTNG_HOME/.lttngrc
           Unix user’s LTTng runtime configuration.

           This is where LTTng stores the name of the Unix user’s current recording session
           between executions of lttng(1).  lttng-create(1) and lttng-set-session(1) set the
           current recording session.

       $LTTNG_HOME/lttng-traces
           Default output directory of LTTng traces in local and snapshot modes.

           Override this path with the --output option of the lttng-create(1) command.

       $LTTNG_HOME/.lttng
           Unix user’s LTTng runtime and configuration directory.

       $LTTNG_HOME/.lttng/sessions
           Default directory containing the Unix user’s saved recording session configurations
           (see lttng-save(1) and lttng-load(1)).

       /etc/lttng/sessions
           Directory containing the system-wide saved recording session configurations (see
           lttng-save(1) and lttng-load(1)).

       Note
           $LTTNG_HOME defaults to the value of the HOME environment variable.

EXAMPLES

       Example 1. List the available context field types.

           See the --list option.

               $ lttng add-context --list

       Example 2. Add a single statically-known context field to be recorded to all the Linux
       kernel channels of the current recording session.

               $ lttng add-context --kernel --type=pid

       Example 3. Add three statically-known context fields to be recorded to a specific user
       space channel of a specific recording session.

           See the --session and --channel options.

               $ lttng add-context --userspace --session=my-session \
                                   --channel=my-channel \
                                   --type=vpid --type=procname --type=ip

       Example 4. Add a perf counter context field to be recorded to a specific Linux kernel
       channel of the current recording session.

           See the --channel option.

               $ lttng add-context --kernel --channel=my-channel \
                                   --type=perf:cpu:cache-misses

       Example 5. Add an LTTng application-specific context field to be recorded to all the JUL
       channels of the current recording session.

               $ lttng add-context --jul --type='$app.my_server:user_cnt'

RESOURCES

       •   LTTng project website <https://lttng.org>

       •   LTTng documentation <https://lttng.org/docs>

       •   LTTng bug tracker <https://bugs.lttng.org>

       •   Git repositories <https://git.lttng.org>

       •   GitHub organization <https://github.com/lttng>

       •   Continuous integration <https://ci.lttng.org/>

       •   Mailing list <https://lists.lttng.org/> for support and development: lttng-
           dev@lists.lttng.org

       •   IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net

COPYRIGHT

       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.