Re: [dpdk-dev] [PATCH 2/8] trace: simplify trace point registration

[Jerin Jacob <jerinjacobk@gmail.com>]

On Mon, May 4, 2020 at 7:34 PM David Marchand <david.marchand@redhat.com> wrote:
>
> On Mon, May 4, 2020 at 4:47 AM Jerin Jacob <jerinjacobk@gmail.com> wrote:
> >
> > On Mon, May 4, 2020 at 2:02 AM David Marchand <david.marchand@redhat.com> wrote:
> > >
> > > RTE_TRACE_POINT_DEFINE and RTE_TRACE_POINT_REGISTER must come in pairs.
> > > Merge them and let RTE_TRACE_POINT_REGISTER handle the constructor part.
> >
> >
> > Initially, I thought of doing the same. But, later I realized that
> > this largely grows the number of constructors been called.
> > I had concerns about the boot time of the application and/or loading
> > the shared library, that the reason why spitting
> > as two so that constructor registers a burst of traces like rte_log.
>
> I am a bit skeptical.
> In terms of cycles and looking at __rte_trace_point_register() (which
> calls malloc), the cost of calling multiple constructors instead of
> one is negligible.

We will have a lot tracepoints latter, each one translates to the
constructor may not be a good
improvement. The scope is limited only to register function so IMO it
is okay to have split
just like rte_log. I don't see any reason why it has to be a different
than rte_log.

One of the thought process is, we probably remove the constructor
scheme to all other with DPDK
and replace it with a more register scheme. In such a case, we can
skip calling the constructor all tother
when trace is disabled.





>
>
> --
> David Marchand
>