[lttng-dev] [documentation] Drawing: LTTng trace session in relation to commandline options

Thibault, Daniel Daniel.Thibault at drdc-rddc.gc.ca
Tue May 27 11:19:27 EDT 2014

Date: Tue, 27 May 2014 13:34:20 +0200
From: Randy Wijnants <dev at tty32.org>

> In addition to the LTTng architecture diagram, I've drawn a diagram that shows the relation between the command line options and how to configure a trace session.
> I hope it proves to be useful, if you have any suggestions let me know!
> Originally posted on IRC. As suggested by Compudj i've released it under CC license.
> http://tty32.org/Trace%20session.png
> http://tty32.org/Trace%20session.svg
> Randy Wijnants.

   Neither the png nor svg versions line up correctly the text and coloured boxes with each other.  This may be a local rendering issue.  At least the svg version has a proper white background (my png renders with a very dark grey background, making it very hard to make out some of the text).  However, the svg version is unusable because none of the text is text: everything is svg:path with opaque d attributes (this may explain the alignment problems).

   Here are improved (more accurate) expressions for the various command syntaxes:

$ lttng create [NAME] [--ctrl-url URL --data-url URL | --output PATH | --set-url URL | --no-output] [--snapshot]
   (the ctrl-url etc. options are in pre-emption order)

$ lttng enable-channel (-k | -u) [--session NAME] NAME[,NAME2,...] [--discard | --overwrite] [--subbuf-size SIZE] [--num-subbuf NUM] [--switch-timer USEC] [--read-timer USEC] \
                                                                                                                [--output (mmap | splice)] [--buffers-uid | --buffers-pid | --buffers-global] [--tracefile-size SIZE [--tracefile-count COUNT]]

$ lttng enable-event (-k | -u) [--session NAME] [--channel NAME] (--all [--tracepoint | --syscall] | \
                                            NAME[,NAME2,...] [--tracepoint [(--loglevel | --loglevel-only) LOGLEVEL] [--filter 'EXPRESSION'] | (--probe | --function) (addr | symbol | symbol+offset)])

$ lttng add-context (-k | -u) [--session NAME] [--channel NAME] (--type TYPE)+

$ lttng list (-k | -u)
   (not the full syntax, but rather the syntax that will get just a list of event names)

$ lttng add-context --help
   (the only one that doesn't change!)

   Change "Kernelspace specific" into "Kernel specific".

   Add footnotes:
* --session NAME defaults to the current session
* --channel NAME in the enable-event case defaults to 'channel0', but only if the domain is virgin
* --channel NAME in the add-context case defaults to all channels

Daniel U. Thibault
Protection des systèmes et contremesures (PSC) | Systems Protection & Countermeasures (SPC)
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