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 <http://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: 5345).

       -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 <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         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 2017-03-13.  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 2.10.0-pre                 03/13/2017                LTTNG-SESSIOND(8)