Fix: add Loading Sessions section to lttng-sessiond.8
[lttng-tools.git] / doc / man / lttng-sessiond.8
1 .TH "LTTNG-SESSIOND" "8" "January 31, 2012" "" ""
3 .SH "NAME"
4 lttng-sessiond \(em LTTng 2.x central tracing registry session daemon.
8 .PP
9 .nf
10 lttng-sessiond [OPTIONS]
11 .fi
14 .PP
15 The LTTng project aims at providing highly efficient tracing tools for Linux.
16 It's tracers help tracking down performance issues and debugging problems
17 involving multiple concurrent processes and threads. Tracing across multiple
18 systems is also possible.
20 The session daemon, acting as a tracing registry, allow you to interact with
21 multiple tracers (kernel and user-space) inside the same container, a tracing
22 session. Trace can be gathered from the kernel and/or instrumented applications
23 (lttng-ust(3)). Aggregating those traces is done using a viewer, like the
24 babeltrace(1) text viewer.
26 In order to trace the kernel, the session daemon needs to be running as root.
27 LTTng provides the use of a \fBtracing group\fP (default: tracing). Whomever is
28 in that group can interact with the root session daemon and thus trace the
29 kernel. Session daemons can co-exist meaning that you can have a session daemon
30 running as Alice that can be used to trace her applications along side with a
31 root daemon or even a Bob daemon. We highly recommend to start the session
32 daemon at boot time for stable and long term tracing.
34 The session daemon is in charge of managing trace data consumers by spawning
35 them when the time has come. The user don't need to manage the lttng-consumerd.
38 .PP
39 This program follow the usual GNU command line syntax with long options starting with
40 two dashes. Below is a summary of the available options.
41 .PP
43 .TP
44 .BR "-h, --help"
45 Show summary of possible options and commands
46 .TP
47 .BR "-v, --verbose"
48 Increase verbosity
50 There is three debugging level which will print on stderr. Maximum verbosity is
51 \fB-vvv\fP.
52 .TP
53 .BR " --verbose-consumer"
54 Verbose mode for consumer. Activate DBG() macro.
55 .TP
56 .BR "-d, --daemonize"
57 Start as a daemon
58 .TP
59 .BR "-b, --background"
60 Start as a daemon, keeping console open
61 .TP
62 .BR "-g, --group=NAME"
63 Specify the tracing group name. (default: tracing)
64 .TP
65 .BR "-V, --version"
66 Show version number
67 .TP
68 .BR "-S, --sig-parent"
69 Send SIGUSR1 to parent pid to notify readiness.
71 This is used by \fBlttng(1)\fP to get notified when the session daemon is ready
72 to accept command. When building a third party tool over liblttng-ctl, this option
73 can be very handy to synchronize the control tool and the session daemon.
74 .TP
75 .BR "-q, --quiet"
76 No output at all.
77 .TP
78 .BR " --no-kernel"
79 No kernel tracer support
80 .TP
81 .BR " --jul-tcp-port"
82 JUL application registration TCP port (default: 5345)
83 .TP
84 .BR " --kmod-probes=probe1, probe2, ..."
85 Specify the kernel modules containing LTTng probes to load by the session daemon.
86 Only the component name of the probe needs to be specified, e.g. to load the
87 lttng-probe-irq and lttng-probe-sched use: --kmod-probes="irq, sched".
88 .TP
89 .BR "-c, --client-sock=PATH"
90 Specify path for the client unix socket
91 .TP
92 .BR "-a, --apps-sock PATH"
93 Specify path for apps unix socket
94 .TP
95 .BR " --kconsumerd-err-sock=PATH"
96 Specify path for the kernel consumer error socket
97 .TP
98 .BR " --kconsumerd-cmd-sock=PATH
99 Specify path for the kernel consumer command socket
100 .TP
101 .BR " --ustconsumerd32-err-sock=PATH
102 Specify path for the 32-bit UST consumer error socket
103 .TP
104 .BR " --ustconsumerd64-err-sock=PATH
105 Specify path for the 64-bit UST consumer error socket
106 .TP
107 .BR " --ustconsumerd32-cmd-sock=PATH
108 Specify path for the 32-bit UST consumer command socket
109 .TP
110 .BR " --ustconsumerd64-cmd-sock=PATH
111 Specify path for the 64-bit UST consumer command socket
112 .TP
113 .BR " --consumerd32-path=PATH
114 Specify path for the 32-bit UST consumer daemon binary
115 .TP
116 .BR " --consumerd32-libdir=PATH
117 Specify path for the 32-bit UST consumer daemon libraries
118 .TP
119 .BR " --consumerd64-path=PATH
120 Specify path for the 64-bit UST consumer daemon binary
121 .TP
122 .BR " --consumerd64-libdir=PATH
123 Specify path for the 64-bit UST consumer daemon libraries
124 .TP
125 .BR "-l, --load PATH
126 Specify path from which to automatically load session configuration(s).
130 .PP
131 By default, the session daemon tries to load session configuration(s) located
132 in the user default directory \fB~/.lttng/sessions/auto/\fP and in the system
133 wide one in \fB/etc/lttng/sessions/auto\fP. Note that the directory containing
134 the session's configuration and lttng-sessiond MUST have the same UID for them
135 to be automatically loaded.
137 Specifiying a path with \-l, \-\-load PATH overrides the default directory and
138 UID check. The lttng-sessiond will simply check if it's accessible and try to
139 load every session file in it.
140 .PP
144 .PP
145 Note that all command line options will override environment variables.
146 .PP
148 .PP
150 Specify the 32-bit consumer binary path. \fB--consumerd32-path\fP
151 override this variable.
153 Specify the 64-bit consumer binary path. \fB--consumerd64-path\fP
154 override this variable.
156 Specifiy the 64-bit library path containing
157 \fB--consumerd32-libdir\fP override this variable.
159 Specifiy the 32-bit library path containing
160 \fB--consumerd64-libdir\fP override this variable.
162 Debug-mode disabling use of clone/fork. Insecure, but required to allow
163 debuggers to work with sessiond on some operating systems.
165 Control the timeout of application's socket when sending and receiving
166 commands. Takes an integer parameter: the timeout value, in seconds.
167 After this period of time, the application is unregistered by the
168 session daemon. A value of 0 or -1 means an infinite timeout. Default
169 value is 5 seconds.
171 Control timeout of socket connection, receive and send. Takes an integer
172 parameter: the timeout value, in milliseconds. A value of 0 or -1 uses
173 the timeout of the operating system (this is the default).
175 Specify the path that contains the XML session configuration schema (xsd).
177 Specify the kernel modules probes that should be loaded by the session daemon.
178 .SH "SEE ALSO"
180 .PP
181 babeltrace(1), lttng-ust(3), lttng(1)
182 .PP
186 .PP
187 For unprivileged user running lttng-sessiond, the maximum number of file
188 descriptors per process is usually 1024. This limits the number of traceable
189 applications since for each instrumented application there is two file
190 descriptors per-CPU and one more socktet for bidirectional communication.
192 For the root user, the limit is bumped to 65535. Future version will deal with
193 this limitation.
194 .PP
196 .SH "BUGS"
198 .PP
199 No show stopper bugs are known yet in this version.
201 If you encounter any issues or usability problem, please report it on our
202 mailing list <> to help improve this project.
205 .PP
206 lttng-sessiond is distributed under the GNU General Public License version 2. See the
207 file COPYING for details.
208 .PP
209 A Web site is available at for more information on the LTTng
210 project.
211 .PP
212 You can also find our git tree at
213 .PP
214 Mailing lists for support and development: <>.
215 .PP
216 You can find us on IRC server (OFTC) in #lttng.
217 .PP
218 .SH "THANKS"
220 .PP
221 Thanks to Yannick Brosseau without whom this project would never have been so
222 lean and mean! Also thanks to the Ericsson teams working on tracing which helped
223 us greatly with detailed bug reports and unusual test cases.
225 Thanks to our beloved packager Alexandre Montplaisir-Goncalves (Ubuntu and PPA
226 maintainer) and Jon Bernard for our Debian packages.
228 Special thanks to Michel Dagenais and the DORSAL laboratory at Polytechnique de
229 Montreal for the LTTng journey.
230 .PP
233 .PP
234 lttng-tools was originally written by Mathieu Desnoyers, Julien Desfossez and
235 David Goulet. More people have since contributed to it. It is currently
236 maintained by David Goulet <>.
237 .PP
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