1 .TH "LTTNG" "1" "July 18th, 2013" "" ""
4 lttng \(em LTTng 2.x tracer control command line tool
9 lttng [OPTIONS] <COMMAND>
13 The LTTng project aims at providing highly efficient tracing tools for Linux.
14 Its tracers help track down performance issues and debug problems
15 involving multiple concurrent processes and threads. Tracing across multiple
16 systems is also possible.
18 The \fBlttng\fP command line tool from the lttng-tools package is used to control
19 both kernel and user-space tracing. Every interaction with the tracer should
20 be done by this tool or by the liblttng-ctl library provided by the lttng-tools
23 LTTng uses a session daemon (lttng-sessiond(8)), acting as a tracing registry,
24 which allows you to interact with multiple tracers (kernel and user-space)
25 inside the same container, a tracing session. Traces can be gathered from the
26 kernel and/or instrumented applications (lttng-ust(3)). Aggregating and reading
27 those traces is done using the babeltrace(1) text viewer.
29 We introduce the notion of \fBtracing domains\fP which is essentially a type of
30 tracer (kernel or user space for now). In the future, we could see a third
31 tracer being for instance an hypervisor. For some commands, you'll need to
32 specify on which domain the command operates (-u or -k). For instance, the
33 kernel domain must be specified when enabling a kernel event.
35 In order to trace the kernel, the session daemon needs to be running as root.
36 LTTng provides the use of a \fBtracing group\fP (default: tracing). Whomever is
37 in that group can interact with the root session daemon and thus trace the
38 kernel. Session daemons can co-exist, meaning that you can have a session daemon
39 running as Alice that can be used to trace her applications along side with a
40 root daemon or even a Bob daemon. We highly recommend starting the session
41 daemon at boot time for stable and long term tracing.
43 All user-space applications instrumented with lttng-ust(3) will
44 automatically register to the session daemon. This feature gives you the
45 ability to list available traceable applications and tracepoints on a per user
46 basis. (See \fBlist\fP command).
50 This program follow the usual GNU command line syntax with long options starting with
51 two dashes. Below is a summary of the available options.
56 Show summary of possible options and commands.
58 .BR "\-v, \-\-verbose"
60 Three levels of verbosity are available which are triggered by putting additional v to
61 the option (\-vv or \-vvv)
64 Suppress all messages (even errors).
66 .BR "\-g, \-\-group NAME"
67 Set unix tracing group name. (default: tracing)
69 .BR "\-n, \-\-no-sessiond"
70 Don't automatically spawn a session daemon.
72 .BR "\-\-sessiond\-path PATH"
73 Set session daemon full binary path.
75 .BR "\-\-list\-options"
76 Simple listing of lttng options.
78 .BR "\-\-list\-commands"
79 Simple listing of lttng commands.
83 \fBadd-context\fP [OPTIONS]
85 Add context to event(s) and/or channel(s).
87 A context is basically extra information appended to a channel. For instance,
88 you could ask the tracer to add the PID information for all events in a
89 channel. You can also add performance monitoring unit counters (perf PMU) using
92 For example, this command will add the context information 'prio' and two perf
93 counters (hardware branch misses and cache misses), to all events in the trace
97 # lttng add-context \-k \-t prio \-t perf:branch-misses \\
101 Please take a look at the help (\-h/\-\-help) for a detailed list of available
104 If no channel is given (\-c), the context is added to all channels that were
105 already enabled. If the session has no channel, a default channel is created.
106 Otherwise the context will be added only to the given channel (\-c).
108 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
115 Show summary of possible options and commands.
117 .BR "\-s, \-\-session NAME"
118 Apply on session name.
120 .BR "\-c, \-\-channel NAME"
121 Apply on channel name.
123 .BR "\-k, \-\-kernel"
124 Apply for the kernel tracer
126 .BR "\-u, \-\-userspace"
127 Apply for the user-space tracer
129 .BR "\-t, \-\-type TYPE"
130 Context type. You can repeat this option on the command line. Please
131 use "lttng add-context \-h" to list all available types.
136 \fBcalibrate\fP [OPTIONS]
138 Quantify LTTng overhead
140 The LTTng calibrate command can be used to find out the combined average
141 overhead of the LTTng tracer and the instrumentation mechanisms used. This
142 overhead can be calibrated in terms of time or using any of the PMU performance
143 counter available on the system.
145 For now, the only calibration implemented is that of the kernel function
146 instrumentation (kretprobes).
148 * Calibrate kernel function instrumentation
150 Let's use an example to show this calibration. We use an i7 processor with 4
151 general-purpose PMU registers. This information is available by issuing dmesg,
152 looking for "generic registers".
154 This sequence of commands will gather a trace executing a kretprobe hooked on
155 an empty function, gathering PMU counters LLC (Last Level Cache) misses
156 information (see lttng add-context \-\-help to see the list of available PMU
160 # lttng create calibrate-function
161 # lttng enable-event calibrate \-\-kernel \\
162 \-\-function lttng_calibrate_kretprobe
163 # lttng add-context \-\-kernel \-t perf:LLC-load-misses \\
164 \-t perf:LLC-store-misses \\
165 \-t perf:LLC-prefetch-misses
167 # for a in $(seq 1 10); do \\
168 lttng calibrate \-\-kernel \-\-function;
171 # babeltrace $(ls \-1drt ~/lttng-traces/calibrate-function-* \\
175 The output from babeltrace can be saved to a text file and opened in a
176 spreadsheet (e.g. oocalc) to focus on the per-PMU counter delta between
177 consecutive "calibrate_entry" and "calibrate_return" events. Note that these
178 counters are per-CPU, so scheduling events would need to be present to account
179 for migration between CPU. Therefore, for calibration purposes, only events
180 staying on the same CPU must be considered.
182 The average result, for the i7, on 10 samples:
186 perf_LLC_load_misses: 5.0 0.577
187 perf_LLC_store_misses: 1.6 0.516
188 perf_LLC_prefetch_misses: 9.0 14.742
191 As we can notice, the load and store misses are relatively stable across runs
192 (their standard deviation is relatively low) compared to the prefetch misses.
193 We can conclude from this information that LLC load and store misses can be
194 accounted for quite precisely, but prefetches within a function seems to behave
195 too erratically (not much causality link between the code executed and the CPU
196 prefetch activity) to be accounted for.
202 Show summary of possible options and commands.
204 .BR "\-k, \-\-kernel"
205 Apply for the kernel tracer
207 .BR "\-u, \-\-userspace"
208 Apply for the user-space tracer
211 Dynamic function entry/return probe (default)
216 \fBcreate\fP [NAME] [OPTIONS]
218 Create tracing session.
220 A tracing session contains channel(s) which contains event(s). It is domain
221 agnostic, meaning that channels and events can be enabled for the
222 user-space tracer and/or the kernel tracer. It acts like a container
223 aggregating multiple tracing sources.
225 On creation, a \fB.lttngrc\fP file is created in your $HOME directory
226 containing the current session name. If NAME is omitted, a session name is
227 automatically created having this form: 'auto-yyyymmdd-hhmmss'.
229 If no \fB\-o, \-\-output\fP is specified, the traces will be written in
232 The $HOME environment variable can be overridden by defining the environment
233 variable LTTNG_HOME. This is useful when the user running the commands has
234 a non-writeable home directory.
240 Show summary of possible options and commands.
242 .BR "\-\-list-options"
243 Simple listing of options
245 .BR "\-o, \-\-output PATH"
246 Specify output path for traces
249 Traces will not be output
252 Set the session in snapshot mode. Created in no-output mode and uses the
253 URL, if one is specified, as the default snapshot output. Every channel will be set
254 in overwrite mode and with mmap output (splice not supported).
257 Set the session exclusively in live mode. The paremeter is the delay in micro
258 seconds before the data is flushed and streamed. The live mode allows you to
259 stream the trace and view it while it's being recorded by any tracer. For that,
260 you need a lttng-relayd and this session requires a network URL (\-U or
263 To read a live session, you can use babeltrace(1) or the live streaming
264 protocol in doc/live-reading-protocol.txt. Here is an example:
267 $ lttng-relayd -o /tmp/lttng
268 $ lttng create --live 200000 -U net://localhost
269 $ lttng enable-event -a --userspace
273 After the start, you'll be able to read the events while they are being
274 recorded in /tmp/lttng.
277 .BR "\-U, \-\-set-url=URL"
278 Set URL for the consumer output destination. It is persistent for the
279 session lifetime. Redo the command to change it. This will set both data
280 and control URL for network.
282 .BR "\-C, \-\-ctrl-url=URL"
283 Set control path URL. (Must use -D also)
285 .BR "\-D, \-\-data-url=URL"
286 Set data path URL. (Must use -C also)
288 Using these options, each API call can be controlled individually. For
289 instance, \-C does not enable the consumer automatically. You'll need the \-e
294 proto://[HOST|IP][:PORT1[:PORT2]][/TRACE_PATH]
296 Supported protocols are (proto):
299 Local filesystem full path.
303 This will use the default network transport layer which is TCP for both
304 control (PORT1) and data port (PORT2). The default ports are
305 respectively 5342 and 5343. Note that net[6]:// is not yet supported.
309 Can only be used with -C and -D together
311 NOTE: IPv6 address MUST be enclosed in brackets '[]' (rfc2732)
316 # lttng create -U net://192.168.1.42
318 Uses TCP and default ports for the given destination.
321 # lttng create -U net6://[fe80::f66d:4ff:fe53:d220]
323 Uses TCP, default ports and IPv6.
326 # lttng create s1 -U net://myhost.com:3229
328 Create session s1 and set its consumer to myhost.com on port 3229 for control.
333 \fBdestroy\fP [NAME] [OPTIONS]
335 Teardown tracing session
337 Free memory on the session daemon and tracer side. It's gone!
339 If NAME is omitted, the session name is taken from the .lttngrc file.
345 Show summary of possible options and commands.
350 .BR "\-\-list-options"
351 Simple listing of options
356 \fBenable-channel\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
358 Enable tracing channel
360 To enable an event, you must enable both the event and the channel that
363 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
366 Exactly one of \-k or -u must be specified.
368 It is important to note that if a certain type of buffers is used, the session
369 will be set with that type and all other subsequent channel needs to have the
372 Note that once the session has been started and enabled on the tracer side,
373 it's not possible anymore to enable a new channel for that session.
381 .BR "\-\-list-options"
382 Simple listing of options
384 .BR "\-s, \-\-session NAME"
385 Apply on session name
387 .BR "\-k, \-\-kernel"
388 Apply to the kernel tracer
390 .BR "\-u, \-\-userspace"
391 Apply to the user-space tracer
394 Discard event when subbuffers are full (default)
397 Flight recorder mode : overwrites events when subbuffers are full
399 .BR "\-\-subbuf-size SIZE"
400 Subbuffer size in bytes {+k,+M,+G}.
401 (default UST uid: 131072, UST pid: 4096, kernel: 262144, metadata: 4096)
402 Rounded up to the next power of 2.
404 The minimum subbuffer size, for each tracer, is the max value between
405 the default above and the system page size. You can issue this command
406 to get the current page size on your system: \fB$ getconf PAGE_SIZE\fP
408 .BR "\-\-num-subbuf NUM"
409 Number of subbuffers. (default UST uid: 4, UST pid: 4, kernel: 4,
410 metadata: 2) Rounded up to the next power of 2.
412 .BR "\-\-switch-timer USEC"
413 Switch subbuffer timer interval in µsec.
414 (default UST uid: 0, UST pid: 0, kernel: 0, metadata: 0)
416 .BR "\-\-read-timer USEC"
417 Read timer interval in µsec.
418 (default UST uid: 0, UST pid: 0, kernel: 200000, metadata: 0)
420 .BR "\-\-output TYPE"
421 Channel output type. Possible values: mmap, splice
422 (default UST uid: mmap, UST pid: mmap, kernel: splice, metadata: mmap)
424 .BR "\-\-buffers-uid"
425 Use per UID buffer (\-u only). Buffers are shared between applications
426 that have the same UID.
428 .BR "\-\-buffers-pid"
429 Use per PID buffer (\-u only). Each application has its own buffers.
431 .BR "\-\-buffers-global"
432 Use shared buffer for the whole system (\-k only)
434 .BR "\-C, \-\-tracefile-size SIZE"
435 Maximum size of each tracefile within a stream (in bytes).
436 0 means unlimited. (default: 0)
438 .BR "\-W, \-\-tracefile-count COUNT"
439 Used in conjunction with \-C option, this will limit the number of files
440 created to the specified count. 0 means unlimited. (default: 0)
445 $ lttng enable-channel -k -C 4096 -W 32 chan1
447 For each stream, the maximum size of each trace file will be 4096 bytes and
448 there will be a maximum of 32 different files. The file count is appended after
449 the stream number as seen in the following example. The last trace file is
450 smaller than 4096 since it was not completely filled.
453 ~/lttng-traces/[...]/chan1_0_0 (4096)
454 ~/lttng-traces/[...]/chan1_0_1 (4096)
455 ~/lttng-traces/[...]/chan1_0_2 (3245)
456 ~/lttng-traces/[...]/chan1_1_0 (4096)
461 $ lttng enable-channel -k -C 4096
463 This will create trace files of 4096 bytes and will create new ones as long as
464 there is data available.
469 \fBenable-event\fP NAME[,NAME2,...] [-k|-u] [OPTIONS]
473 A tracing event is always assigned to a channel. If \fB\-c, \-\-channel\fP is
474 omitted, a default channel named '\fBchannel0\fP' is created and the event is
475 added to it. If \fB\-c, \-\-channel\fP is omitted, but a non-default
476 channel already exists within the session, an error is returned. For the
477 user-space tracer, using \fB\-a, \-\-all\fP is the same as using the
480 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
487 Show summary of possible options and commands.
489 .BR "\-\-list-options"
490 Simple listing of options
492 .BR "\-s, \-\-session NAME"
493 Apply on session name
495 .BR "\-c, \-\-channel NAME"
496 Apply on channel name
499 Enable all tracepoints and syscalls. This actually enables a single
502 .BR "\-k, \-\-kernel"
503 Apply for the kernel tracer
505 .BR "\-u, \-\-userspace"
506 Apply for the user-space tracer
509 Tracepoint event (default). Userspace tracer supports wildcards at the end
510 of string. Don't forget to quote to deal with bash expansion.
517 .BR "\-\-loglevel NAME"
518 Tracepoint loglevel range from 0 to loglevel. Listed in the help (\-h).
520 .BR "\-\-loglevel-only NAME"
521 Tracepoint loglevel (only this loglevel).
522 The loglevel or loglevel-only options should be combined with a
523 tracepoint name or tracepoint wildcard.
525 .BR "\-\-probe (addr | symbol | symbol+offset)"
526 Dynamic probe. Addr and offset can be octal (0NNN...), decimal (NNN...)
527 or hexadecimal (0xNNN...)
529 .BR "\-\-function (addr | symbol | symbol+offset)"
530 Dynamic function entry/return probe. Addr and offset can be octal
531 (0NNN...), decimal (NNN...) or hexadecimal (0xNNN...)
534 System call event. Enabling syscalls tracing (kernel tracer), you will
535 not be able to disable them with disable-event. This is a known
536 limitation. You can disable the entire channel to do the trick.
538 .BR "\-\-filter 'expression'"
539 Set a filter on a newly enabled event. Filter expression on event
540 fields and context. The event will be recorded if the filter's
541 expression evaluates to TRUE. Only specify on first activation of a
542 given event within a session.
543 Specifying a filter is only allowed when enabling events within a session before
544 tracing is started. If the filter fails to link with the event
545 within the traced domain, the event will be discarded.
546 Filtering is currently only implemented for the user-space tracer.
551 'intfield > 500 && intfield < 503'
552 '(strfield == "test" || intfield != 10) && intfield > 33'
553 'doublefield > 1.1 && intfield < 5.3'
556 Wildcards are allowed at the end of strings:
558 In string literals, the escape character is a '\\'. Use '\\*' for
559 the '*' character, and '\\\\' for the '\\' character sequence. Wildcard
560 matches any sequence of characters, including an empty sub-string
561 (matches 0 or more characters).
563 Context information can be used for filtering. The examples below shows
564 usage of context filtering on the process name (using a wildcard), process ID
565 range, and unique thread ID. The process and thread IDs of
566 running applications can be found under columns "PID" and "LWP" of the
570 '$ctx.procname == "demo*"'
571 '$ctx.vpid >= 4433 && $ctx.vpid < 4455'
579 \fBdisable-channel\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
581 Disable tracing channel
583 Disabling a channel disables the tracing of all of the channel's events. A channel
584 can be reenabled by calling \fBlttng enable-channel NAME\fP again.
586 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
593 Show summary of possible options and commands.
595 .BR "\-\-list-options"
596 Simple listing of options
598 .BR "\-s, \-\-session NAME"
599 Apply on session name
601 .BR "\-k, \-\-kernel"
602 Apply for the kernel tracer
604 .BR "\-u, \-\-userspace"
605 Apply for the user-space tracer
610 \fBdisable-event\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
612 Disable tracing event
614 The event, once disabled, can be re-enabled by calling \fBlttng enable-event
617 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
620 If \fB\-c, \-\-channel\fP is omitted, the default channel name is used.
621 If \fB\-c, \-\-channel\fP is omitted, but a non-default channel already
622 exists within the session, an error is returned.
628 Show summary of possible options and commands.
630 .BR "\-\-list-options"
631 Simple listing of options
633 .BR "\-s, \-\-session NAME"
634 Apply on session name
636 .BR "\-c, \-\-channel NAME"
637 Apply on channel name
639 .BR "\-a, \-\-all-events"
640 Disable all events. This does NOT disable "*" but rather every known
641 events of the session.
643 .BR "\-k, \-\-kernel"
644 Apply for the kernel tracer
646 .BR "\-u, \-\-userspace"
647 Apply for the user-space tracer
652 \fBlist\fP [OPTIONS] [SESSION [SESSION OPTIONS]]
654 List tracing session information.
656 With no arguments, it will list available tracing session(s).
658 With the session name, it will display the details of the session including
659 the trace file path, the associated channels and their state (activated
660 and deactivated), the activated events and more.
662 With \-k alone, it will list all available kernel events (except the system
664 With \-u alone, it will list all available user-space events from registered
665 applications. Here is an example of 'lttng list \-u':
668 PID: 7448 - Name: /tmp/lttng-ust/tests/hello/.libs/lt-hello
669 ust_tests_hello:tptest_sighandler (type: tracepoint)
670 ust_tests_hello:tptest (type: tracepoint)
673 You can now enable any event listed by using the name :
674 \fBust_tests_hello:tptest\fP.
680 Show summary of possible options and commands.
682 .BR "\-\-list-options"
683 Simple listing of options
685 .BR "\-k, \-\-kernel"
688 .BR "\-u, \-\-userspace"
689 Select user-space domain.
695 .BR "\-c, \-\-channel NAME"
696 List details of a channel
698 .BR "\-d, \-\-domain"
699 List available domain(s)
704 \fBset-session\fP NAME [OPTIONS]
706 Set current session name
708 Will change the session name in the .lttngrc file.
714 Show summary of possible options and commands.
716 .BR "\-\-list-options"
717 Simple listing of options
722 \fBsnapshot\fP [OPTIONS] ACTION
724 Snapshot command for LTTng session.
730 Show summary of possible options and commands.
732 .BR "\-\-list-options"
733 Simple listing of options
739 \fBadd-output\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] <URL> | -C <URL> -D <URL>
741 Setup and add an snapshot output for a session. Output are the destination
742 where the snapshot will be sent. Only one output is permitted. To change it,
743 you'll need to delete it and add back the new one.
746 \fBdel-output\fP ID | NAME [-s <NAME>]
748 Delete an output for a session using the ID. You can either specify the
749 output's ID that can be found with list-output or the name.
752 \fBlist-output\fP [-s <NAME>]
754 List the output of a session. Attributes of the output are printed.
757 \fBrecord\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] [<URL> | -C <URL> -D <URL>]
759 Snapshot a session's buffer(s) for all domains. If an URL is specified, it is
760 used instead of a previously added output. Specifying only a name or/and a max
761 size will override the current output values. For instance, you can record a
762 snapshot with a custom maximum size or with a different name.
765 $ lttng snapshot add-output -n mysnapshot file:///data/snapshot
767 $ lttng snapshot record -n new_name_snapshot
770 The above will create a snapshot in /data/snapshot/new_name_snapshot* directory
771 rather then in mysnapshot*/
774 .B DETAILED ACTION OPTIONS
777 .BR "\-s, \-\-session NAME"
778 Apply to session name.
780 .BR "\-n, \-\-name NAME"
781 Name of the snapshot's output.
783 .BR "\-m, \-\-max-size SIZE"
784 Maximum size in bytes of the snapshot. The maxium size does not include the
785 metadata file. Human readable format is accepted: {+k,+M,+G}. For instance,
788 .BR "\-C, \-\-ctrl-url URL"
789 Set control path URL. (Must use -D also)
791 .BR "\-D, \-\-data-url URL"
792 Set data path URL. (Must use -C also)
797 \fBstart\fP [NAME] [OPTIONS]
801 It will start tracing for all tracers for a specific tracing session.
802 If NAME is omitted, the session name is taken from the .lttngrc file.
808 Show summary of possible options and commands.
810 .BR "\-\-list-options"
811 Simple listing of options
816 \fBstop\fP [NAME] [OPTIONS]
820 It will stop tracing for all tracers for a specific tracing session. Before
821 returning, the command checks for data availability meaning that it will wait
822 until the trace is readable for the session. Use \-\-no-wait to avoid this
825 If NAME is omitted, the session name is taken from the .lttngrc file.
831 Show summary of possible options and commands.
833 .BR "\-\-list-options"
834 Simple listing of options
836 Don't wait for data availability.
843 Show version information
849 Show summary of possible options and commands.
851 .BR "\-\-list-options"
852 Simple listing of options
857 \fBview\fP [SESSION_NAME] [OPTIONS]
859 View traces of a tracing session. By default, the babeltrace viewer
860 will be used for text viewing. If SESSION_NAME is omitted, the session
861 name is taken from the .lttngrc file.
869 .BR "\-\-list-options"
870 Simple listing of options
872 .BR "\-t, \-\-trace-path PATH"
873 Trace directory path for the viewer
875 .BR "\-e, \-\-viewer CMD"
876 Specify viewer and/or options to use This will completely override the
877 default viewers so please make sure to specify the full command. The
878 trace directory path of the session will be appended at the end to the
885 On success 0 is returned and a positive value on error. Value of 1 means a command
886 error, 2 an undefined command, 3 a fatal error and 4 a command warning meaning that
887 something went wrong during the command.
889 Any other value above 10, please refer to
890 .BR "<lttng/lttng-error.h>"
891 for a detailed list or use lttng_strerror() to get a human readable string of
895 .SH "ENVIRONMENT VARIABLES"
898 Note that all command line options override environment variables.
902 .IP "LTTNG_SESSIOND_PATH"
903 Allows one to specify the full session daemon binary path to lttng command line
904 tool. You can also use \-\-sessiond-path option having the same effect.
910 .BR lttng-sessiond(8),
916 If you encounter any issues or usability problem, please report it on our
917 mailing list <lttng-dev@lists.lttng.org> to help improve this project or
918 at https://bugs.lttng.org which is a bugtracker.
924 lttng is distributed under the GNU General Public License version 2. See the file
927 A Web site is available at http://lttng.org for more information on the LTTng
930 You can also find our git tree at http://git.lttng.org.
932 Mailing lists for support and development: <lttng-dev@lists.lttng.org>.
934 You can find us on IRC server irc.oftc.net (OFTC) in #lttng.
939 Thanks to Yannick Brosseau without whom this project would never have been so
940 lean and mean! Also thanks to the Ericsson teams working on tracing which
941 helped us greatly with detailed bug reports and unusual test cases.
943 Thanks to our beloved packager Alexandre Montplaisir-Goncalves (Ubuntu and PPA
944 maintainer) and Jon Bernard for our Debian packages.
946 Special thanks to Michel Dagenais and the DORSAL laboratory at Polytechnique de
947 Montreal for the LTTng journey.
952 lttng-tools was originally written by Mathieu Desnoyers, Julien Desfossez and
953 David Goulet. More people have since contributed to it. It is currently
954 maintained by David Goulet <dgoulet@efficios.com>.