[lttng-dev] lttng command line user-friendliness

Woegerer, Paul Paul_Woegerer at mentor.com
Mon Sep 10 07:25:34 EDT 2012

As much as I like the lttng command line tool (that we have since 
LTTng2) I still see people (who are not yet familiar with lttng) 
struggle with the simple fact that it takes more than one command to 
actually get something traced.

Issuing a sequence of commands like:

lttng create
lttng enable-event -u -a
lttng start
my_foobar_traced_application 1 2 3
lttng stop
lttng destroy

seems to be perceived as complicated compared to:

perf record -- my_foobar_traced_application 1 2 3

My argument usually is that providing detailed settings as options (like 
perf) does not scale as well as the lttng approach (if you have more 
things to configure). On the other hand most users just want something 
like the above. Also arguing that they should write a shell-script that 
encodes their use case generally causes irritation ("... please 
understand, I do not want to write a shell-script I just want to do 
simple tracing of my executable ...").

What about adding something similar to "perf record" to lower the 
barrier for such users. For example:

lttng record [--session-name <name>] [--session-template 
<session_template_file>]  -- <command> [<options>]

Where the optional session_template_file may only contain 
"enable-channel, enable-event and add-context" commands. If omitted the 
following could be the (trivial) default session template:

enable-event -u -a

Would this make sense for others as well ? Any alternative suggestions ?


Paul Woegerer | SW Development Engineer

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