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

[Philippe Proulx]

On Sat, Oct 18, 2014 at 10:39 AM, Boisvert, Sebastien <boisvert at anl.gov> wrote:
>
> Hi,
>
> I changed the provider name to thorium_message.
>
> I also tried using a macro in the template file, but the define alone
> breaks things.
>
> Template file: https://github.com/sebhtml/biosal/blob/master/engine/thorium/tracepoints/lttng/message.tp (the macro is commented)
>
>
> Uncommenting the macro produces these warnings:
>
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
> Warning: different domain provided (int,thorium_message)
>
> And the linker fails.

Yes, sorry about that, I didn't look at the output.

lttng-gen-tp has some bugs. It parses everything using regexes, so I guess it
won't deal properly with custom C preprocessor stuff reusing
TRACEPOINT_EVENT() within a macro. For some reason, it detects `int` as
the tracepoint provider name ("domain" in lttng-gen-tp's jargon).

IMO your use case might already be too advanced for lttng-gen-tp, so I would
advise that you have a look at defining plain tracepoint providers without
using lttng-gen-tp: <http://lttng.org/docs/#doc-tracepoint-provider>. It
basically involves writing a proper template header. The hardest part
is defining
the tracepoints using TRACEPOINT_EVENT(), but you already did that.

So start with this (TP provider name fixed):

  * message.h: <http://pastebin.com/yiqN0CEj>
  * message.c: <http://pastebin.com/BmXiSCbd>

Build it like this:

    gcc -I../../../.. -I. -c message.c

and link the resulting message.o with your application as usual.

>
> > ________________________________________
> > From: Philippe Proulx [eeppeliteloop at gmail.com]
> > Sent: Friday, October 17, 2014 9:36 PM
> > To: Boisvert, Sebastien
> > Cc: lttng-dev at lists.lttng.org
> > Subject: Re: [lttng-dev] Writing .tp files for lttng-gen-tp
> > On Fri, Oct 17, 2014 at 5:39 PM, Boisvert, Sebastien <boisvert at anl.gov> wrote:
> > > Hi,
> > >
> > > 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 ?
> > Yes; note that a template file is just part of an eventual C header
> > file, so C preprocessor
> > stuff is accepted. This should work:
> > #include <engine/thorium/message.h>
> > #define THORIUM_MSG_TP(name) \
> > TRACEPOINT_EVENT( \
> > message, \
> > name, \
> > TP_ARGS( \
> > struct thorium_message *, msg \
> > ), \
> > TP_FIELDS( \
> > ctf_integer(int, message_number, msg->number) \
> > ctf_integer(int, message_action, msg->action) \
> > ctf_integer(int, message_count, msg->count) \
> > ctf_integer(int, message_source_actor, msg->source_actor) \
> > ctf_integer(int, message_destination_actor,
> > msg->destination_actor) \
> > ctf_integer(int, message_source_node, msg->source_node) \
> > ctf_integer(int, message_destination_node,
> > msg->destination_node) \
> > ) \
> > )
> > THORIUM_MSG_TP(actor_send)
> > THORIUM_MSG_TP(node_send)
> > THORIUM_MSG_TP(worker_send)
> > THORIUM_MSG_TP(worker_receive)
> > THORIUM_MSG_TP(worker_send_mailbox)
> > THORIUM_MSG_TP(worker_send_schedule)
> > THORIUM_MSG_TP(worker_pool_enqueue)
> > THORIUM_MSG_TP(worker_pool_dequeue)
> > THORIUM_MSG_TP(worker_enqueue_message)
> > THORIUM_MSG_TP(actor_receive)
> > THORIUM_MSG_TP(worker_dequeue_message)
> > THORIUM_MSG_TP(node_send_system)
> > THORIUM_MSG_TP(node_receive)
> > THORIUM_MSG_TP(node_receive_message)
> > THORIUM_MSG_TP(node_send_dispatch)
> > THORIUM_MSG_TP(node_dispatch_message)
> > THORIUM_MSG_TP(transport_send)
> > THORIUM_MSG_TP(transport_receive)
> > Please write back if it does not.
> > BTW, I would suggest that your tracepoint provider name (currently `message`) be
> > more specific as to what your application really is, e.g., `thorium_msg`.
> > Phil
> > >
> > >
> > >                 Sébastien
> > >
> > >
> > > _______________________________________________
> > > lttng-dev mailing list
> > > lttng-dev at lists.lttng.org
> > > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev