Re: [PATCH v4] eal: add build-time option to omit trace

[Jerin Jacob <jerinjacobk@gmail.com>]

On Tue, Oct 1, 2024 at 9:32 PM Morten Brørup <mb@smartsharesystems.com> wrote:
>
> > From: Jerin Jacob [mailto:jerinjacobk@gmail.com]
> > Sent: Tuesday, 1 October 2024 17.02
> >
> > On Tue, Oct 1, 2024 at 7:44 PM Morten Brørup <mb@smartsharesystems.com>
> > wrote:
> > >
> > > > From: Jerin Jacob [mailto:jerinjacobk@gmail.com]
> > > > Sent: Tuesday, 1 October 2024 16.05
> > > >
> > > > On Tue, Oct 1, 2024 at 7:19 PM Morten Brørup
> > <mb@smartsharesystems.com>
> > > > wrote:
> > > > >
> > > > > Jerin,
> > > > >
> > > > > If you have no further comments, please add review/ack tag, to
> > help
> > > > Thomas see that the patch has been accepted by the maintainer, and
> > can
> > > > be merged.
> > > >
> > > > There was a comment to make the function as rte_trace_is_enabled()
> > and
> > > > remove internal. The rest looks good to me. I will Ack in the next
> > > > version.
> > >
> > > Perhaps my reply to that comment was unclear... such a public
> > function already exists in the previous API:
> >
> > I see. It was not clear.
> >
> > >
> > https://elixir.bootlin.com/dpdk/v24.07/source/lib/eal/include/rte_trace
> > .h#L36
> > >
> > > That function tells if trace enabled at both build time and runtime,
> > and returns false if not.
> > >
> > > A separate public function to tell if trace is enabled at build time
> > seems like overkill to me. Is that what you are asking for?
> >
> > No. Just use rte_trace_is_enabled() in app/test instead of
> > __rte_trace_point_generic_is_enabled() as it is internal.
>
> Just tested it, and it didn't have the wanted effect.
> I think rte_trace_is_enabled() returns false until at least one tracepoint has been enabled, which seems like a good optimization.
> But it also means that we cannot use it to replace __rte_trace_point_generic_is_enabled() in test/app, because no tracepoints have been enabled at this point of execution, so it returns false here.
>
> I looked around in the code, and cannot find a method without looking at internals, or duplicating a test case.
>
> I could test if rte_trace_point_lookup("app.dpdk.test.tp") returns non-NULL, but that would duplicate the same test in test_trace_points_lookup().
>
> What do you think...
> Keep using internal function __rte_trace_point_generic_is_enabled(),
> test rte_trace_point_lookup("app.dpdk.test.tp") != NULL,
> or any other idea?

How about the following, it is anyway the correct thing to do

bool
rte_trace_is_enabled(void)
{
 +       if (__rte_trace_point_generic_is_enabled() == false)
  +              return false;
        return rte_atomic_load_explicit(&trace.status,
rte_memory_order_acquire) != 0;
}


>