[dpdk-dev] [PATCH v6 33/33] doc: add trace library guide

[Jerin Jacob]

On Tue, Apr 21, 2020 at 5:49 AM Thomas Monjalon <thomas at monjalon.net> wrote:
>
> Hi,
>
> Below is a doc review.
> General comment: it is better to split lines after punctuation signs
> in order to make future patches easier to read.

Thanks for the review.
Except below two comments, Everything else accepted and fixed in v7.

> > +
> > +Register the tracepoint
> > +~~~~~~~~~~~~~~~~~~~~~~~
> > +
> > +.. code-block:: c
> > +
> > + #define RTE_TRACE_POINT_REGISTER_SELECT /* Select trace point register macros */
>
> I don't understand this #define.

See the headerfile.
/**
 * Macro to select rte_trace_point_emit_* definition for trace register function
 *
 * rte_trace_point_emit_* emits different definitions for trace function.
 * Application must define RTE_TRACE_POINT_REGISTER_SELECT before including
 * rte_trace_point.h in the C file where RTE_TRACE_POINT_REGISTER used.
 *
 * @see RTE_TRACE_POINT_REGISTER
 */
#define RTE_TRACE_POINT_REGISTER_SELECT

>
> > +Trace file location
> > +-------------------
> > +
> > +On ``rte_trace_save()`` or ``rte_eal_cleanup()`` invocation, the library saves
> > +the trace buffers to the filesystem. By default, library saves trace files at
> > +``$HOME/dpdk-traces/rte-yyyy-mm-dd-[AP]M-hh-mm-ss/``. It can be overridden by
>
> Please don't create a specific directory, but use rte_eal_get_runtime_dir().

Trace files are huge in size, /var/run is not the correct place to store it.
User needs to have control over where the trace file generated.It can
be different than rte_eal_get_runtime_dir().
Multiple DPDK application running case has been taken care of by using
eal_get_hugefile_prefix() in trace session creation.


> > +the ``--trace-dir=<directory path>`` EAL command line option.
>
> I don't think this option is needed.
> XDG_RUNTIME_DIR environment variable can do the same.