[RFC 2/5] common/mlx5: introduce tracepoints for mlx5 drivers

[Thomas Monjalon]

27/06/2023 10:19, Slava Ovsiienko:
> From: Thomas Monjalon <thomas at monjalon.net>
> > 27/06/2023 08:15, Slava Ovsiienko:
> > > From: Thomas Monjalon <thomas at monjalon.net>
> > > > 13/06/2023 18:01, Jerin Jacob:
> > > > > On Tue, Jun 13, 2023 at 9:29 PM Slava Ovsiienko
> > > > > <viacheslavo at nvidia.com>
> > > > wrote:
> > > > > > From: Jerin Jacob <jerinjacobk at gmail.com>
> > > > > > > On Tue, Jun 13, 2023 at 9:20 PM Slava Ovsiienko
> > > > > > > <viacheslavo at nvidia.com>
> > > > > > > wrote:
> > > > > > > >
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > <..snip..>
> > > > > > > > > >
> > > > > > > > > >         mlx5_os_interrupt_handler_create; #
> > WINDOWS_NO_EXPORT
> > > > > > > > > >         mlx5_os_interrupt_handler_destroy; #
> > > > > > > > > > WINDOWS_NO_EXPORT
> > > > > > > > > > +
> > > > > > > > > > +       __rte_pmd_mlx5_trace_tx_entry;
> > > > > > > > > > +       __rte_pmd_mlx5_trace_tx_exit;
> > > > > > > > > > +       __rte_pmd_mlx5_trace_tx_wqe;
> > > > > > > > > > +       __rte_pmd_mlx5_trace_tx_wait;
> > > > > > > > > > +       __rte_pmd_mlx5_trace_tx_push;
> > > > > > > > > > +       __rte_pmd_mlx5_trace_tx_complete;
> > > > > > > > >
> > > > > > > > > No need to expose these symbols. It is getting removed
> > > > > > > > > from rest of
> > > > DPDK.
> > > > > > > > > Application can do rte_trace_lookup() to get this address.
> > > > > > > > >
> > > > > > > > >
> > > > > > > > It is not for application, it is for PMD itself, w/o
> > > > > > > > exposing the symbols build
> > > > > > > failed.
> > > > > > >
> > > > > > > PMD is implementing this trace endpoints, not consuming this
> > > > > > > trace
> > > > point.
> > > > > > > Right? If so, Why to expose these symbols?
> > > > > >
> > > > > > As far as understand:
> > > > > > The tracepoint routines are defined in dedicated
> > > > > > common/mlx5_trace.c
> > > > file.
> > > > > > The tx_burst in mlx5 is implemented as template in header file,
> > > > > > and this template is used in multiple .c files under net/mlx5 filder.
> > > > > > So, common/mlx5 should expose its symbols to net/mlx5 to allow
> > > > > > successful linkage.
> > > > >
> > > > > OK. I missed the fact the these are in common code and net driver
> > > > > is depened on that.
> > > > > So changes makes sense.
> > > >
> > > > It does not make sense to me.
> > > > These are tracepoints for the ethdev driver.
> > > > Why declaring them in the common library?
> > >
> > > Just to gather all mlx5 traces in the single file, to see all available tracing
> > caps in single view.
> > 
> > Better to not export them.
> > 
> It is not about export, we have analyzing script over the trace data, and it would be better to see all the tracing
> routines gathered in one place. I would prefer not to spread trace point definitions over the multiple source files.

You don't need to export trace symbols for using them.
It has been discussed already with Jerin that we prefer not exporting
trace symbols if it can be avoided. Here it can be avoided.