Provided by: lttng-tools_2.10.7-1_amd64 bug

NAME

       lttng-sessiond - LTTng 2 tracing session daemon

SYNOPSIS

       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

       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

   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

       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

       $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

       0
           Success

       1
           Error

       3
           Fatal error

LIMITATIONS

       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

       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>.

SEE ALSO

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