Re: [RFC 0/8] eal: dynamic logs

[Olivier Matz <olivier.matz@6wind.com>]

Hi Bruce,

On Mon, 6 Feb 2017 13:49:03 +0000, Bruce Richardson
<bruce.richardson@intel.com> wrote:
> On Mon, Feb 06, 2017 at 02:29:08PM +0100, Olivier Matz wrote:
> > The objective of this RFC patchset is to introduce a framework to
> > support dynamic log types in EAL. It also provides one example of
> > use (in i40e).
> > 
> > Features:
> > - log types are identified by a string
> > - at registration, a uniq identifier is associated to a log type
> > - each log type can have its level changed dynamically
> > - extend command line parameters to set the log level of a specific
> >   type, or logs matching a regular expression
> > - keep compat with other legacy types (eal, malloc, ring, user*,
> >   etc... keep their hardcoded log type value)
> > 
> > At the end, when, we can expect that all non-dataplane logs are
> > moved to be dynamic, so we can enable/disable them at runtime,
> > without recompiling. Many debug options can probably be removed from
> > configuration:
> >   $ git grep DEBUG config/common_base | wc -l
> >   89
> > 
> > Comments are welcome!
> >   
> Initial scan through the patches this looks pretty good. However,
> rather than continuing with our own logging system, have you
> investigated what other tracing and logging systems might be out
> there that we could possibly re-use? Could LTTng be a good fit for
> DPDK, perhaps?

I did not investigate much about existing logging system. I agree
that could be a good alternative too.

On the other hand, I'm not really confident in adding a dependency to
an external lib for a core component like eal. What if we deicide
tomorrow to port dpdk to windows or any baremetal env?

Also, as far as I remember, the components that depend on external
libraries are disabled today because we don't know how to properly
manage the dependency (ex: pmd-pcap, vhost-numa, pmd-mlx, ...).


Olivier