1LTTNG-SESSIOND(8) LTTng Manual LTTNG-SESSIOND(8)
2
6 lttng-sessiond - LTTng 2 tracing session daemon
7
9 lttng-sessiond [--background | --daemonize] [--sig-parent]
10 [--config=PATH] [--group=GROUP] [--load=PATH]
11 [--agent-tcp-port=PORT]
12 [--apps-sock=PATH] [--client-sock=PATH]
13 [--no-kernel | [--kmod-probes=PROBE[,PROBE]...]
14 [--extra-kmod-probes=PROBE[,PROBE]...]
15 [--kconsumerd-err-sock=PATH]
16 [--kconsumerd-cmd-sock=PATH]]
17 [--ustconsumerd32-err-sock=PATH]
18 [--ustconsumerd64-err-sock=PATH]
19 [--ustconsumerd32-cmd-sock=PATH]
20 [--ustconsumerd64-cmd-sock=PATH]
21 [--consumerd32-path=PATH] [--consumerd32-libdir=PATH]
22 [--consumerd64-path=PATH] [--consumerd64-libdir=PATH]
23 [--quiet | [-v | -vv | -vvv] [--verbose-consumer]]
24
26 The Linux Trace Toolkit: next generation <http://lttng.org/> is an open
27 source software package used for correlated tracing of the Linux
28 kernel, user applications, and user libraries.
29 LTTng consists of Linux kernel modules (for Linux kernel tracing) and
31 dynamically loaded libraries (for user application and library
32 tracing).
33 The LTTng session daemon is a tracing registry which allows the user to
35 interact with multiple tracers (kernel and user space) within the same
36 container, a tracing session. Traces can be gathered from the Linux
37 kernel and/or from instrumented applications (see lttng-ust(3)). You
38 can aggregate and read the events of LTTng traces using babeltrace(1).
39 To trace the Linux kernel, the session daemon needs to be running as
41 root. LTTng uses a tracing group to allow specific users to interact
42 with the root session daemon. The default tracing group name is
43 tracing. You can use the --group option to set the tracing group name
44 to use.
45 Session daemons can coexist. You can have a session daemon running as
47 user Alice that can be used to trace her applications alongside a root
48 session daemon or a session daemon running as user Bob.
49 The LTTng session daemon manages trace data consumer daemons by
51 spawning them when necessary. You do not need to manage the consumer
52 daemons manually.
53 Note
55 It is highly recommended to start the session daemon at boot time
56 for stable and long-term tracing.
57 Automatic loading of tracing session configurations
59 When the session daemon starts, it automatically loads session
60 configuration files.
61 The following directories are searched, non-recursively, in this order
63 for configuration files to load on launch:
64 1. $LTTNG_HOME/.lttng/sessions/auto ($LTTNG_HOME defaults to $HOME)
66 2. /usr/local/etc/lttng/sessions/auto
68 Note that both the directory containing the tracing session
70 configurations and the session daemon binary must share the same UID
71 for the configurations to be automatically loaded.
72 The --load option overrides the default directories and the UID check.
74 The session daemon simply checks if the path is accessible and tries to
75 load every tracing session configuration in it. When this option is
76 specified, the default directories are NOT searched for configuration
77 files. When the option is not specified, both default directories are
78 searched for configuration files.
79 If the --load option’s argument is a directory, then all the tracing
81 session configurations found in all the files in this directory are
82 loaded. If the argument is a file, then all the tracing session
83 configurations found in this file are loaded.
84
86 Daemon configuration
87 -b, --background
88 Start as Unix daemon, but keep file descriptors (console) open. Use
89 the --daemonize option instead to close the file descriptors.
90 -d, --daemonize
92 Start as Unix daemon, and close file descriptors (console). Use the
93 --background option instead to keep the file descriptors open.
94 -f, --config=PATH
96 Load session daemon configuration from path PATH.
97 -g, --group=GROUP
99 Use GROUP as Unix tracing group (default: tracing).
100 -l, --load=PATH
102 Automatically load tracing session configurations from PATH, either
103 a directory or a file, instead of loading them from the default
104 search directories.
105 -S, --sig-parent
107 Send SIGUSR1 to parent process to notify readiness.
108 Note
110 This is used by lttng(1) to get notified when the session
111 daemon is ready to accept commands. When building a third party
112 tool on liblttng-ctl, this option can be very handy to
113 synchronize the control tool and the session daemon.
114 Linux kernel tracing
116 --extra-kmod-probes=PROBE[,PROBE]...
117 Load specific LTTng Linux kernel modules when kernel tracing is
118 enabled (--no-kernel option is NOT specified), in addition to
119 loading the default list of LTTng kernel modules.
120 Only the name of the probe needs to be specified, without the
122 lttng-probe- prefix and without the kernel module extension suffix.
123 For example, specify sched to load the lttng-probe-sched.ko kernel
124 module.
125 --kmod-probes=PROBE[,PROBE]...
127 Only load specific LTTng Linux kernel modules when kernel tracing
128 is enabled (--no-kernel option is NOT specified).
129 Only the name of the probe needs to be specified, without the
131 lttng-probe- prefix and without the kernel module extension suffix.
132 For example, specify sched to load the lttng-probe-sched.ko kernel
133 module.
134 --no-kernel
136 Disable Linux kernel tracing.
137 Paths and ports
139 --agent-tcp-port=PORT
140 Listen on TCP port PORT for agent application registrations
141 (default: a port withinin the range [5345, 5354]).
142 -a PATH, --apps-sock=PATH
144 Set application Unix socket path to PATH.
145 -c PATH, --client-sock=PATH
147 Set client Unix socket path to PATH.
148 --consumerd32-libdir=PATH
150 Set 32-bit consumer daemon library directory to PATH.
151 --consumerd32-path=PATH
153 Set 32-bit consumer daemon binary path to PATH.
154 --consumerd64-libdir=PATH
156 Set 64-bit consumer daemon library directory to PATH.
157 --consumerd64-path=PATH
159 Set 64-bit consumer daemon binary path to PATH.
160 --kconsumerd-cmd-sock=PATH
162 Set Linux kernel consumer daemon’s command Unix socket path to
163 PATH.
164 --kconsumerd-err-sock=PATH
166 Set Linux kernel consumer daemon’s error Unix socket path to PATH.
167 --ustconsumerd32-cmd-sock=PATH
169 Set 32-bit consumer daemon’s command Unix socket path to PATH.
170 --ustconsumerd64-cmd-sock=PATH
172 Set 64-bit consumer daemon’s command Unix socket path to PATH.
173 --ustconsumerd32-err-sock=PATH
175 Set 32-bit consumer daemon’s error Unix socket path to PATH.
176 --ustconsumerd64-err-sock=PATH
178 Set 64-bit consumer daemon’s error Unix socket path to PATH.
179 Verbosity
181 -q, --quiet
182 Suppress all messages, including warnings and errors.
183 -v, --verbose
185 Increase verbosity.
186 Three levels of verbosity are available, which are triggered by
188 appending additional v letters to the option (that is, -vv and
189 -vvv).
190 --verbose-consumer
192 Increase verbosity of consumer daemons spawned by this session
193 daemon.
194 Program information
196 -h, --help
197 Show help.
198 -V, --version
200 Show version.
201
203 Note that command-line options override their equivalent environment
204 variable.
205 LTTNG_ABORT_ON_ERROR
207 Set to 1 to abort the process after the first error is encountered.
208 LTTNG_APP_SOCKET_TIMEOUT
210 Application socket’s timeout (seconds) when sending/receiving
211 commands. After this period of time, the application is
212 unregistered by the session daemon. A value of 0 or -1 means an
213 infinite timeout. Default value: 5.
214 LTTNG_CONSUMERD32_BIN
216 32-bit consumer daemon binary path.
217 The --consumerd32-path option overrides this variable.
219 LTTNG_CONSUMERD32_LIBDIR
221 32-bit consumer daemon library path.
222 The --consumerd32-libdir option overrides this variable.
224 LTTNG_CONSUMERD64_BIN
226 64-bit consumer daemon binary path.
227 The --consumerd64-path option overrides this variable.
229 LTTNG_CONSUMERD64_LIBDIR
231 64-bit consumer daemon library path.
232 The --consumerd64-libdir option overrides this variable.
234 LTTNG_DEBUG_NOCLONE
236 Set to 1 to disable the use of clone()/fork(). Setting this
237 variable is considered insecure, but it is required to allow
238 debuggers to work with the session daemon on some operating
239 systems.
240 LTTNG_EXTRA_KMOD_PROBES
242 Load specific LTTng Linux kernel modules when kernel tracing is
243 enabled (--no-kernel option is NOT specified), in addition to
244 loading the default list of LTTng kernel modules.
245 The --extra-kmod-probes option overrides this variable.
247 LTTNG_KMOD_PROBES
249 Only load specific LTTng Linux kernel modules when kernel tracing
250 is enabled (--no-kernel option is NOT specified).
251 The --kmod-probes option overrides this variable.
253 LTTNG_NETWORK_SOCKET_TIMEOUT
255 Socket connection, receive and send timeout (milliseconds). A value
256 of 0 or -1 uses the timeout of the operating system (default).
257 LTTNG_SESSION_CONFIG_XSD_PATH
259 Tracing session configuration XML schema definition (XSD) path.
260
262 $LTTNG_HOME/.lttng
263 User LTTng runtime and configuration directory.
264 $LTTNG_HOME/lttng-traces
266 Default output directory of LTTng traces. This can be overridden
267 with the --output option of the lttng-create(1) command.
268 $LTTNG_HOME/.lttng/sessions/auto
270 Directory from which user tracing configuration files are
271 automatically loaded when the session daemon starts (see lttng-
272 save(1) and lttng-load(1) for saving and loading tracing sessions).
273 /usr/local/etc/lttng/sessions/auto
275 Directory from which system-wide tracing configuration files are
276 automatically loaded when the session daemon starts (see lttng-
277 save(1) and lttng-load(1) for saving and loading tracing sessions).
278 $LTTNG_HOME/.lttng/lttng.conf
280 Default location of the session daemon configuration file (see the
281 --config option).
282 /usr/local/etc/lttng/lttng.conf
284 System-wide location of the session daemon configuration file (see
285 the --config option).
286 Note
288 $LTTNG_HOME defaults to $HOME when not explicitly set.
289
291 0
292 Success
293 1
295 Error
296 3
298 Fatal error
299
301 For an unprivileged user running lttng-sessiond, the maximum number of
302 file descriptors per process is usually 1024. This limits the number of
303 traceable applications, since for each instrumented application, there
304 is two file descriptors per CPU and one more socket for bidirectional
305 communication.
306 For the root user, the limit is bumped to 65535. A future version will
308 deal with this limitation.
309
311 If you encounter any issue or usability problem, please report it on
312 the LTTng bug tracker <https://bugs.lttng.org/projects/lttng-tools>.
313
315 · LTTng project website <http://lttng.org>
316 · LTTng documentation <http://lttng.org/docs>
318 · Git repositories <http://git.lttng.org>
320 · GitHub organization <http://github.com/lttng>
322 · Continuous integration <http://ci.lttng.org/>
324 · Mailing list <http://lists.lttng.org> for support and development:
326 lttng-dev@lists.lttng.org
327 · IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net
329
331 This program is part of the LTTng-tools project.
332 LTTng-tools is distributed under the GNU General Public License version
334 2 <http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html>. See the
335 LICENSE <https://github.com/lttng/lttng-tools/blob/master/LICENSE> file
336 for details.
337
339 Special thanks to Michel Dagenais and the DORSAL laboratory
340 <http://www.dorsal.polymtl.ca/> at École Polytechnique de Montréal for
341 the LTTng journey.
342 Also thanks to the Ericsson teams working on tracing which helped us
344 greatly with detailed bug reports and unusual test cases.
345
347 LTTng-tools was originally written by Mathieu Desnoyers, Julien
348 Desfossez, and David Goulet. More people have since contributed to it.
349 LTTng-tools is currently maintained by Jérémie Galarneau
351 <mailto:jeremie.galarneau@efficios.com>.
352
354 lttng(1), lttng-relayd(8), lttng-crash(1), lttng-ust(3), babeltrace(1)
355LTTng 2.10.5 07/24/2018 LTTNG-SESSIOND(8)