[lttng-dev] Writing .tp files for lttng-gen-tp

[Boisvert, Sebastien]

Are TRACEPOINT_EVENT_CLASS and
TRACEPOINT_EVENT_INSTANCE part of the LTTng-UST end user interface
(are these stable between release) ?

If so, I will gladly give it a try !

> ________________________________________
> From: Thibault, Daniel [Daniel.Thibault at drdc-rddc.gc.ca]
> Sent: Monday, October 20, 2014 8:29 AM
> To: lttng-dev at lists.lttng.org
> Cc: Boisvert, Sebastien
> Subject: RE: [lttng-dev] Writing .tp files for lttng-gen-tp
> ----------------------------------------------------------------------
> Date: Fri, 17 Oct 2014 21:39:21 +0000
> From: "Boisvert, Sebastien" <boisvert at anl.gov>
> > I wrote a big .tp file to define numerous tracepoints that only differ in the event name.
> > They all take the same arguments and they all dump the same fields.
> >
> > .tp file: https://github.com/sebhtml/biosal/blob/master/engine/thorium/tracepoints/lttng/message.tp
> >
> > Is there a more compact way of doing that ?
> >
> >               Sébastien
> ----------------------------------------------------------------------
>    In the kernel domain, one can declare a "tracepoint class" with DECLARE_EVENT_CLASS, and then use DEFINE_EVENT to instantiate the abstract event class into individual trace events that share a single signature.  Surely the same can be done in user-space?
>    Looking at /usr/src/lttng-ust/include/lttng/tracepoint.h, we see there are TRACEPOINT_EVENT_CLASS and TRACEPOINT_EVENT_INSTANCE macros right beside TRACEPOINT_EVENT, so I suspect you could replace your message.tp with something like:
> [...]
> TRACEPOINT_EVENT_CLASS(
> thorium_message,
> thorium_event_template,
> TP_ARGS(
> struct thorium_message *, message
> ),
> TP_FIELDS(
> ctf_integer(int, message_number, message->number)
> ctf_integer(int, message_action, message->action)
> ctf_integer(int, message_count, message->count)
> ctf_integer(int, message_source_actor, message->source_actor)
> ctf_integer(int, message_destination_actor, message->destination_actor)
> ctf_integer(int, message_source_node, message->source_node)
> ctf_integer(int, message_destination_node, message->destination_node)
> )
> )
> TRACEPOINT_EVENT_INSTANCE(
> thorium_message,
> thorium_event_template,
> actor_send,
> TP_ARGS(
> struct thorium_message *, message
> )
> )
> TRACEPOINT_EVENT_INSTANCE(
> thorium_message,
> thorium_event_template,
> node_send,
> TP_ARGS(
> struct thorium_message *, message
> )
> )
> [...]
>    Try it and let us know.  This should be added to the lttng-gen-tp man pages if it works.
> Daniel U. Thibault
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