lttng-sessiond(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT VARIABLES | FILES | EXIT STATUS | LIMITATIONS | BUGS | RESOURCES | COPYRIGHTS | THANKS | AUTHORS | SEE ALSO | COLOPHON

LTTNG-SESSIOND(8)             LTTng Manual             LTTNG-SESSIOND(8)

NAME         top

       lttng-sessiond - LTTng 2 tracing session daemon

SYNOPSIS         top

       lttng-sessiond [--background | --daemonize] [--sig-parent]
                      [--config=PATH] [--group=GROUP] [--load=PATH]
                      [--agent-tcp-port=PORT]
                      [--apps-sock=PATH] [--client-sock=PATH]
                      [--no-kernel | [--kmod-probes=PROBE[,PROBE]...]
                                     [--extra-kmod-probes=PROBE[,PROBE]...]
                                     [--kconsumerd-err-sock=PATH]
                                     [--kconsumerd-cmd-sock=PATH]]
                      [--ustconsumerd32-err-sock=PATH]
                      [--ustconsumerd64-err-sock=PATH]
                      [--ustconsumerd32-cmd-sock=PATH]
                      [--ustconsumerd64-cmd-sock=PATH]
                      [--consumerd32-path=PATH] [--consumerd32-libdir=PATH]
                      [--consumerd64-path=PATH] [--consumerd64-libdir=PATH]
                      [--quiet | [-v | -vv | -vvv] [--verbose-consumer]]

DESCRIPTION         top

       The Linux Trace Toolkit: next generation <https://lttng.org/> is
       an open source software package used for correlated tracing of
       the Linux kernel, user applications, and user libraries.

       LTTng consists of Linux kernel modules (for Linux kernel tracing)
       and dynamically loaded libraries (for user application and
       library tracing).

       The LTTng session daemon is a tracing registry which allows the
       user to interact with multiple tracers (kernel and user space)
       within the same container, a tracing session. Traces can be
       gathered from the Linux kernel and/or from instrumented
       applications (see lttng-ust(3)). You can aggregate and read the
       events of LTTng traces using babeltrace(1).

       To trace the Linux kernel, the session daemon needs to be running
       as root. LTTng uses a tracing group to allow specific users to
       interact with the root session daemon. The default tracing group
       name is tracing. You can use the --group option to set the
       tracing group name to use.

       Session daemons can coexist. You can have a session daemon
       running as user Alice that can be used to trace her applications
       alongside a root session daemon or a session daemon running as
       user Bob.

       The LTTng session daemon manages trace data consumer daemons by
       spawning them when necessary. You do not need to manage the
       consumer daemons manually.

           Note

           It is highly recommended to start the session daemon at boot
           time for stable and long-term tracing.

   Automatic loading of tracing session configurations
       When the session daemon starts, it automatically loads session
       configuration files.

       The following directories are searched, non-recursively, in this
       order for configuration files to load on launch:

        1. $LTTNG_HOME/.lttng/sessions/auto ($LTTNG_HOME defaults to
           $HOME)

        2. /usr/local/etc/lttng/sessions/auto

       Note that both the directory containing the tracing session
       configurations and the session daemon binary must share the same
       UID for the configurations to be automatically loaded.

       The --load option overrides the default directories and the UID
       check. The session daemon simply checks if the path is accessible
       and tries to load every tracing session configuration in it. When
       this option is specified, the default directories are NOT
       searched for configuration files. When the option is not
       specified, both default directories are searched for
       configuration files.

       If the --load option’s argument is a directory, then all the
       tracing session configurations found in all the files in this
       directory are loaded. If the argument is a file, then all the
       tracing session configurations found in this file are loaded.

OPTIONS         top

   Daemon configuration
       -b, --background
           Start as Unix daemon, but keep file descriptors (console)
           open. Use the --daemonize option instead to close the file
           descriptors.

       -d, --daemonize
           Start as Unix daemon, and close file descriptors (console).
           Use the --background option instead to keep the file
           descriptors open.

       -f, --config=PATH
           Load session daemon configuration from path PATH.

       -g, --group=GROUP
           Use GROUP as Unix tracing group (default: tracing).

       -l, --load=PATH
           Automatically load tracing session configurations from PATH,
           either a directory or a file, instead of loading them from
           the default search directories.

       -S, --sig-parent
           Send SIGUSR1 to parent process to notify readiness.

               Note
               This is used by lttng(1) to get notified when the session
               daemon is ready to accept commands. When building a third
               party tool on liblttng-ctl, this option can be very handy
               to synchronize the control tool and the session daemon.

   Linux kernel tracing
       --extra-kmod-probes=PROBE[,PROBE]...
           Load specific LTTng Linux kernel modules when kernel tracing
           is enabled (--no-kernel option is NOT specified), in addition
           to loading the default list of LTTng kernel modules.

           Only the name of the probe needs to be specified, without the
           lttng-probe- prefix and without the kernel module extension
           suffix. For example, specify sched to load the lttng-probe-
           sched.ko kernel module.

       --kmod-probes=PROBE[,PROBE]...
           Only load specific LTTng Linux kernel modules when kernel
           tracing is enabled (--no-kernel option is NOT specified).

           Only the name of the probe needs to be specified, without the
           lttng-probe- prefix and without the kernel module extension
           suffix. For example, specify sched to load the lttng-probe-
           sched.ko kernel module.

       --no-kernel
           Disable Linux kernel tracing.

   Paths and ports
       --agent-tcp-port=PORT
           Listen on TCP port PORT for agent application registrations
           (default: a port within the range [5345, 5354]).

       -a PATH, --apps-sock=PATH
           Set application Unix socket path to PATH.

       -c PATH, --client-sock=PATH
           Set client Unix socket path to PATH.

       --consumerd32-libdir=PATH
           Set 32-bit consumer daemon library directory to PATH.

       --consumerd32-path=PATH
           Set 32-bit consumer daemon binary path to PATH.

       --consumerd64-libdir=PATH
           Set 64-bit consumer daemon library directory to PATH.

       --consumerd64-path=PATH
           Set 64-bit consumer daemon binary path to PATH.

       --kconsumerd-cmd-sock=PATH
           Set Linux kernel consumer daemon’s command Unix socket path
           to PATH.

       --kconsumerd-err-sock=PATH
           Set Linux kernel consumer daemon’s error Unix socket path to
           PATH.

       --ustconsumerd32-cmd-sock=PATH
           Set 32-bit consumer daemon’s command Unix socket path to
           PATH.

       --ustconsumerd64-cmd-sock=PATH
           Set 64-bit consumer daemon’s command Unix socket path to
           PATH.

       --ustconsumerd32-err-sock=PATH
           Set 32-bit consumer daemon’s error Unix socket path to PATH.

       --ustconsumerd64-err-sock=PATH
           Set 64-bit consumer daemon’s error Unix socket path to PATH.

   Verbosity
       -q, --quiet
           Suppress all messages, including warnings and errors.

       -v, --verbose
           Increase verbosity.

           Three levels of verbosity are available, which are triggered
           by appending additional v letters to the option (that is, -vv
           and -vvv).

       --verbose-consumer
           Increase verbosity of consumer daemons spawned by this
           session daemon.

   Program information
       -h, --help
           Show help.

       -V, --version
           Show version.

ENVIRONMENT VARIABLES         top

       Note that command-line options override their equivalent
       environment variable.

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

       LTTNG_APP_SOCKET_TIMEOUT
           Application socket’s timeout (seconds) when sending/receiving
           commands. After this period of time, the application is
           unregistered by the session daemon. A value of 0 or -1 means
           an infinite timeout. Default value: 5.

       LTTNG_CONSUMERD32_BIN
           32-bit consumer daemon binary path.

           The --consumerd32-path option overrides this variable.

       LTTNG_CONSUMERD32_LIBDIR
           32-bit consumer daemon library path.

           The --consumerd32-libdir option overrides this variable.

       LTTNG_CONSUMERD64_BIN
           64-bit consumer daemon binary path.

           The --consumerd64-path option overrides this variable.

       LTTNG_CONSUMERD64_LIBDIR
           64-bit consumer daemon library path.

           The --consumerd64-libdir option overrides this variable.

       LTTNG_DEBUG_NOCLONE
           Set to 1 to disable the use of clone()/fork(). Setting this
           variable is considered insecure, but it is required to allow
           debuggers to work with the session daemon on some operating
           systems.

       LTTNG_EXTRA_KMOD_PROBES
           Load specific LTTng Linux kernel modules when kernel tracing
           is enabled (--no-kernel option is NOT specified), in addition
           to loading the default list of LTTng kernel modules.

           The --extra-kmod-probes option overrides this variable.

       LTTNG_KMOD_PROBES
           Only load specific LTTng Linux kernel modules when kernel
           tracing is enabled (--no-kernel option is NOT specified).

           The --kmod-probes option overrides this variable.

       LTTNG_NETWORK_SOCKET_TIMEOUT
           Socket connection, receive and send timeout (milliseconds). A
           value of 0 or -1 uses the timeout of the operating system
           (default).

       LTTNG_SESSION_CONFIG_XSD_PATH
           Tracing session configuration XML schema definition (XSD)
           path.

FILES         top

       $LTTNG_HOME/.lttng
           User LTTng runtime and configuration directory.

       $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/sessions/auto
           Directory from which user tracing configuration files are
           automatically loaded when the session daemon starts (see
           lttng-save(1) and lttng-load(1) for saving and loading
           tracing sessions).

       /usr/local/etc/lttng/sessions/auto
           Directory from which system-wide tracing configuration files
           are automatically loaded when the session daemon starts (see
           lttng-save(1) and lttng-load(1) for saving and loading
           tracing sessions).

       $LTTNG_HOME/.lttng/lttng.conf
           Default location of the session daemon configuration file
           (see the --config option).

       /usr/local/etc/lttng/lttng.conf
           System-wide location of the session daemon configuration file
           (see the --config option).

           Note

           $LTTNG_HOME defaults to $HOME when not explicitly set.

EXIT STATUS         top

       0
           Success

       1
           Error

       3
           Fatal error

LIMITATIONS         top

       For an unprivileged user running lttng-sessiond, the maximum
       number of file descriptors per process is usually 1024. This
       limits the number of traceable applications, since for each
       instrumented application, there is two file descriptors per CPU
       and one more socket for bidirectional communication.

       For the root user, the limit is bumped to 65535. A future version
       will deal with this limitation.

BUGS         top

       If you encounter any issue or usability problem, please report it
       on the LTTng bug tracker <https://bugs.lttng.org/projects/lttng-
       tools>.

RESOURCES         top

       •   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         top

       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         top

       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         top

       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         top

       lttng(1), lttng-relayd(8), lttng-crash(1), lttng-ust(3),
       babeltrace(1)

COLOPHON         top

       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
       problems in this HTML version of the page, or you believe there
       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-SESSIOND(8)

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